Everyday Calculators
Age, date, GPA, fuel cost, sleep, BTU, concrete, time-card and other free everyday utility calculators.
Age Calculator | Get Exact Age Between Two Dates
An age calculator computes the exact time elapsed between two dates in years, months, weeks, days, hours, minutes, and seconds. People use it to check their precise age in days, find an age difference between two people, or work out how long until a specific date — leap years and varying month lengths handled automatically.
Age Difference Calculator | Compute exact age gap and totals
The Age Difference Calculator finds the exact gap between two people's ages — in years, months and days — from their dates of birth. It also shows who is older and the total difference expressed in months, weeks and days.
AI API Cost Calculator | Estimate Token and Monthly Usage Costs
Project your AI API spend from token counts and provider rates — input, output, and cached tokens per request times your request volume. Compare models and providers side by side, and see daily, monthly, and yearly cost for any workload before you commit to it.
Average Time Calculator | Find Mean Time From Multiple Entries
Finds the average of multiple time values. Enter a list of times in hours, minutes, and seconds, and the tool converts them all to seconds, computes the mean, and converts the result back into hours, minutes, and seconds — useful for tracking average shift lengths, workouts, or task durations.
Birthday Countdown Calculator | Countdown To Your Next Birthday
Counts down to your next birthday. Enter your birth date, and the tool calculates exactly how many days and sleeps remain until your birthday this year, the day of the week it falls on, and your age when you reach it.
Bra Size Calculator | Determine Band, Cup, and Sister Sizes
Find your bra size from two tape measurements — band and bust — with the cup-difference method applied and sister sizes shown. Measure once, get your starting size, and use the sister-size chart to fine-tune the fit across brands.
BTU Calculator | Recommend Heating or Cooling Capacity for Rooms
Determines the heating or cooling capacity a room needs in BTUs. Enter the room's square footage, ceiling height, sun exposure, insulation quality, and number of occupants, and the tool applies standard BTU-per-square-foot factors to recommend the right air-conditioner or heater size for the space.
Carbon Footprint Calculator | Estimate annual CO2 emissions
Estimates your annual carbon footprint in tonnes of CO2. Enter details about your driving miles, flights, home electricity and gas use, and dietary habits, and the tool applies standard emission factors to each category. The results show where your emissions come from and how you compare with national averages.
Concrete Calculator | Estimate Volume and Number of Bags Needed
Estimates how much concrete a project needs. Enter the slab, footing, or column dimensions — length, width, and depth — and the tool computes the volume in cubic yards and cubic metres, then converts it to the number of 40 lb, 60 lb, or 80 lb bags, with an allowance for waste.
Cron Expression Builder | Validate and Find Next Run Times
Build and validate standard five-field cron expressions, with each field explained as you type and the next five run times calculated live. Spot impossible schedules instantly — the tool flags invalid combinations like February 31 and copies the working expression for your scheduler.
Date Calculator | Count days, weeks, months, and years between dates
Pick two dates and this calculator returns the exact number of days, weeks, months, and years between them, including or excluding the endpoints as you choose. It also lets you add or subtract days from a date — perfect for counting down to deadlines, due dates, or events, and for checking how much time has passed.
Days Alive Calculator | Calculate Days, Weeks, and Months Lived
Calculates exactly how many days you have been alive. Enter your birth date and an optional end date, and the tool returns the total days, weeks, and months lived, including leap-day handling, plus the day of the week you were born on.
Days From Today Calculator | Find Date N Days Ahead Or Behind
Finds the exact date any number of days from today — or in the past. Enter a number of days and choose forward or backward, and the tool returns the resulting date, the weekday, and the month and year, accounting for month lengths and leap years automatically.
Density Calculator | Compute mass, volume, or density using formula
Solves density, mass, and volume problems. Enter any two of the three values and the tool computes the missing one using density = mass ÷ volume, with the formula shown. It also provides reference densities for common materials, such as water, so results can be checked against real-world values.
Dew Point Calculator | Calculate Dew Point from Temp and Humidity
Finds the dew point from air temperature and relative humidity. Enter the temperature in Celsius or Fahrenheit and the humidity percentage, and the tool applies the Magnus formula to compute the dew point, then interprets what it means — the temperature at which condensation forms, and how muggy the air will feel.
E-commerce Profit Margin Calculator | Estimate Net Profit per Order
Find the true net profit per order for your e-commerce store — revenue minus product cost, shipping, marketplace fees, discounts, refunds, and ad spend. See the margin percentage and the per-order picture that shows whether each sale actually makes money.
Electricity Calculator | Calculate Appliance Energy Use and Cost
Calculate what your appliances cost to run from wattage, daily usage and your electricity rate — daily, monthly and yearly totals. Audit your home's energy use and find the biggest savings in your bill.
Engine Horsepower Calculator | From Torque & RPM
An engine horsepower calculator converts measured torque at a given engine speed into horsepower with the relationship HP = torque(lb-ft) × RPM ÷ 5,252. Because 5,252 is where torque and horsepower curves cross on a dyno chart, any RPM below it shows more torque than horsepower, and any RPM above shows more horsepower.
Etsy Fee Calculator | See Net Profit After All Etsy Fees
Shows the real profit on an Etsy sale after every fee. Enter your item price, shipping cost, and sale quantity, and the tool deducts Etsy's listing fee, transaction fee, payment-processing fee, and offsite-ad fee where applicable. You see the true net profit per item and your profit margin at a glance.
EV Charging Cost and Time Calculator | Compare Charging Costs
Compare home and public EV charging — cost per charge from your battery size, rate, and charging losses, plus the time each charger type takes and the savings versus a petrol car. The numbers you need to budget electric driving accurately.
EV Charging Cost Calculator | Estimate EV charging costs
Calculate how much it costs to charge your electric car from your battery size, charge range and electricity rate, with charging losses accounted for. Compare home and public charging and budget your EV properly.
Freelance Rate Calculator | Set Hourly, Daily, and Project Rates
Find the hourly rate you need to charge to hit your target income, including business expenses and self-employment taxes, based on your real billable hours. The rate-setting math every freelancer and contractor needs.
Fuel Cost Calculator | Estimate Trip Fuel Cost and Cost Per Mile
Estimate the fuel cost of any trip from distance, fuel efficiency and price, with a round-trip toggle and per-passenger split. Budget road trips, compare routes and settle the gas money fairly.
Fuel Tank Capacity Calculator | Find Tank Volume From Dimensions
Calculate fuel tank capacity in gallons and litres from the tank's dimensions — rectangular or cylindrical — with partial-fill levels supported. Size tanks, check fuel remaining from a dipstick reading, and plan refuels.
GDP Calculator | Compute Nominal and Real GDP From Expenditure
Calculate GDP with the expenditure approach — consumption, investment, government and net exports — and convert between nominal and real values with a deflator. The macroeconomics formula applied clearly for coursework and analysis.
Golf Handicap Calculator | Compute handicap differential from a round
Calculate your golf score differential from your score, course rating and slope rating, using the standard formula with the 113 normalization. Track each round and see the scores that build your handicap index.
GPA Calculator | Compute Semester and Cumulative GPA With Weights
Calculate your GPA from letter grades and credit hours, weighted correctly by credit, with the 4.0 scale conversion shown. Track semester and cumulative GPA and see exactly what your final exams need to deliver.
GPA Planner Calculator | Project Your Graduation GPA
Project your final GPA from current average, completed credits, and the credits you have left — and see exactly what average you need in remaining courses to hit your graduation target. The weighted math shows whether your goal is still attainable and how hard the remaining semesters must be.
Grade Calculator | Find Current Grade and Needed Final Exam Score
Find your current weighted grade from assignment scores and weights, then work out the score you need on the final exam to hit your target. The gradebook math every student needs — enter your scores and get the answer.
Grade Goal Calculator | Find the Score Needed on Remaining Work
Find the exact score you need on remaining assignments and finals to hit your target grade — enter your current grade, the target, and how much of the course is still ahead, and see whether the goal is realistic before exam season.
Gravel Calculator | Estimate Cubic Yards And Tons From Area
Work out how much gravel, crushed stone or topsoil you need — in cubic yards and tons — from the length, width and depth of the area. The tool applies each material's density and shows the coverage per yard, so you order the right amount for driveways, paths and landscaping.
Heat Index Calculator | Compute Feels-Like Temp and Heat Risk
Calculates the heat index — how hot the air actually feels — from temperature and humidity. Enter the air temperature and relative humidity, and the tool applies the National Weather Service Rothfusz equation to return the feels-like temperature, then classifies it into caution, extreme caution, danger, or extreme danger categories.
Heat Pump Savings Calculator | Compare Heating Costs
Compare your current heating costs against a heat pump — enter your fuel type, local rates, and seasonal efficiency, and see the annual saving, payback, and the difference in cost per unit of heat delivered.
Height Calculator | Convert Units and Predict Adult Height
Converts height measurements between imperial and metric systems and estimates how tall a child will grow. Enter a height in feet and inches or centimetres, and the tool converts it instantly to the other unit. The child-growth mode uses the mid-parental height formula to predict adult height from both parents' heights.
Home Energy Usage Calculator | Estimate Appliance Electricity Cost
Break your electricity bill down appliance by appliance — wattage, hours, and rate become daily, monthly, and yearly costs. Find the biggest energy users in your home and see exactly what each change to usage or efficiency saves on the bill.
Horsepower Calculator | Compute Horsepower From Torque and RPM
Estimate horsepower from torque and RPM, or from quarter-mile trap speed and vehicle weight, with the formulas shown. Compare cars, plan modifications and understand the power-to-weight ratio.
Hours Calculator | Find elapsed time and decimal hours for payroll
Calculate hours and minutes between two times, minus breaks, in both h:mm and decimal format. Sum shifts, check timesheets and plan schedules — the simple time math done right.
How Long Have We Been Together Calculator | Get exact time
Calculates exactly how long a couple has been together in years, months and days, with totals and the next anniversary countdown.
How Old Am I Calculator | Calculate Exact Age And Time Lived
Calculates your exact age from your date of birth. Enter your birth date, and the tool returns your age in years, months, and days, plus the total weeks, days, hours, and minutes lived, with the day of the week you were born — useful for forms, milestones, and fun facts.
I’tikaf Days Calculator | Find Ramadan’s Last Ten Nights
The I'tikaf Days calculator shows when the last ten nights of Ramadan begin and end, so you can plan your i'tikaf (spiritual retreat) in the mosque.
JSON, YAML and XML Formatter | Validate and Convert Data
Format, validate, and inspect JSON, YAML, or XML directly in your browser without uploading anything. Indent messy documents, catch syntax errors with clear messages, and keep sensitive configuration local — the developer's daily helper for data files and API payloads.
Khums Calculator (Shia) | Compute 20% Khums After Expenses
The Khums calculator (Shia) works out the 20% Khums due on your annual surplus after legitimate living expenses, split between the share of the Imam and the share of the sadat.
Mass Calculator | Solve mass, density, or volume and convert units
Calculate mass from density and volume, or solve for density or volume when the other two are known, with unit conversions applied. The complete mass-density-volume tool for physics, chemistry and engineering.
Mileage Calculator | Track Fuel Economy, Cost Per Mile, and Trips
Calculate fuel economy in MPG and L/100km from miles driven and gallons used, and compute mileage reimbursement at any rate. Track your car's real efficiency and get your business-mileage payouts right.
Missed Prayers Qadha Calculator | Estimate missed prayers’ time
The Missed Prayers (Qadha) calculator estimates how many obligatory prayers you need to make up over a period of years, months and days, and how long it will take to clear them at your chosen daily pace.
Molarity Calculator | Compute Moles, Molarity, Mass, or Volume
Solves solution-concentration problems. Enter any three of molarity, moles, mass, and volume — along with the solute's molar mass — and the tool computes the missing value in mol/L, grams, or litres, with the formula shown. Essential for chemistry lab prep and homework checks.
Molecular Weight Calculator | Molar Mass in g/mol & Moles
Computes the molar mass of any chemical formula. Enter a formula like H2O or C6H12O6, and the tool sums the atomic masses of every element present using standard atomic weights, returning the molar mass in g/mol, and converts between grams and moles for the given mass.
MPG Calculator | Compute Fuel Economy In MPG, L/100km, And km/L
Calculates your vehicle's real fuel economy. Enter the miles driven and the gallons of fuel used, and the tool returns MPG, litres per 100 km, and kilometres per litre, with a note on how your driving style and conditions affect the result.
Mulch Calculator | Estimate Volume and Bags Needed for Beds
Measure your garden bed's length and width, choose the mulch depth you want (1–4 inches), and this mulch calculator returns the volume needed in cubic yards and cubic feet, plus an estimate of how many standard bags to buy. It also covers round beds and triangle-shaped areas, so you can order exactly what your landscaping project needs.
Ohm’s Law Calculator | Solve Voltage, Current & Power
Solve for voltage, current, resistance or power in any circuit with Ohm's law and the power formula, entering any two values. The four rearrangements are shown with each step — the electrician's and electronics student's essential tool.
Paint Calculator | Estimate Paint Quantity and Cost
Estimate how many gallons or litres of paint you need from room dimensions, doors and windows, coats, and the coverage rate on the can — plus the total paint cost at your price per gallon. The result rounds up to whole cans so you buy exactly what the job takes.
Pizza Calculator | Compute Slices Needed and Pizzas to Order
Work out how many pizzas to order for your group from guest count, slices per person and pizza size. Never run out — and never order two extra pizzas nobody eats.
Quranic Verse Juz Counter | Estimate finish date by Juz pace
The Quranic Juz Counter shows how long it will take to complete the Quran by juz at your daily pace, with the verses remaining and an estimated finish date.
Regex Tester and Explainer | Test Matches and Capture Groups
Test JavaScript regular expressions against sample text with live match highlighting, capture-group extraction, and flag controls. Build, debug, and explain patterns in seconds — each match, group, and flag effect is visible instantly as you type.
Resistor Calculator | Decode Colour Bands and Combine Values
Decode resistor color bands into resistance values, and generate the band code for any resistance you need. The essential electronics reference — read 4- and 5-band resistors correctly every time.
Roofing Calculator | Estimate Roof Area and Shingle Needs
Estimate your roof area in squares from the house footprint and pitch, with the slope factor applied, plus shingle bundles at the waste percentage you choose. Order the right materials for the roofing job.
SaaS MRR Calculator | Project ARR, LTV, Churn, and CAC Payback
Model the core SaaS unit economics — MRR, ARR, LTV, churn impact, and CAC payback — from customers, pricing, and retention inputs. See how churn erodes growth and what payback your acquisition spend really needs, using the standard simplified formulas.
Septic Tank Size Calculator | Estimate Tank Size From Bedrooms
Sizes a septic tank for a home based on the number of bedrooms and occupants. Enter the number of bedrooms, and the tool applies standard US sizing rules — typically 750 to 1,500 gallons — to recommend the minimum tank capacity, with guidance on local codes and usage factors.
Shoe Size Conversion | Convert US, UK, EU, and cm Sizes
Converts shoe sizes between US, UK, EU, and centimetre systems. Enter a size in any system and choose whether it is for men, women, or kids, and the tool returns the equivalent sizes in every other system, with the measurement in centimetres, so international online shopping fits first time.
Sleep Calculator | Find Bedtimes and Wake Times by Sleep Cycles
Find the ideal bedtime for your wake time using 90-minute sleep cycles, so you wake between cycles instead of mid-REM. Choose 5 or 6 cycles and get the exact times that leave you feeling rested.
Solar Battery Payback Calculator | Estimate Storage ROI
Work out whether a home solar battery is worth it — from installed cost, usable capacity, and your tariff structure, see the payback period, lifetime return, and how much peak-rate energy you can shift each day.
Solar Panel Savings Calculator | Estimate savings & payback
Estimates the financial return of installing solar panels. Enter your monthly electricity bill, the total system cost, and the percentage of your usage the panels will offset, and the tool projects your first-year savings, annual bill reduction, and the payback period — how many years until the system pays for itself.
Speed Calculator | Compute Speed, Distance or Time, Convert Units
Calculate speed, distance or time from any two values, with conversions between km/h, mph, m/s and knots. Plan journeys, check average speeds and convert running paces — the travel math solved.
Square Footage Calculator | Measure area in square feet and meters
Measure room areas in square feet with multi-section support for L-shaped spaces, plus square-metre and square-yard conversions. The number you need for flooring, paint, tile and real-estate comparisons.
Stair Calculator | Design Steps from Total Rise with Rise and Run
Designs a staircase from the total rise. Enter the height from the finished floor to the landing, and the tool uses a comfortable rise-and-run rule of thumb to calculate the number of steps, the rise and run of each step, and the total horizontal run the staircase will occupy.
Subscription Cost Calculator | Compare Monthly and Annual Spending
Total up every subscription — streaming, software, gym, cloud, and more — into one monthly and yearly figure. Enter each service and its price, and the calculator converts annual plans to monthly equivalents so you can spot what your recurring spending really adds up to.
Tile Calculator | Calculate tiles needed, waste allowance, and packs
Calculate how many tiles you need from the room area, tile size and waste percentage, rounded up to whole tiles. Includes grout considerations and the 10–15% waste rule — order the right quantity for the job.
Tile Calculator | Estimate Tiles, Waste, Grout, and Cost
Estimate how many tiles you need for any room — including cutting waste, grout, adhesive, and the full material cost. Enter the room and tile dimensions, choose the waste percentage for your layout, and get whole-tile counts rounded up so you order exactly the right quantity.
Time Card Calculator | Total Hours, Overtime, and Estimated Pay
Totals work hours from daily time-card entries. Enter clock-in and clock-out times for each day of the week, along with unpaid breaks, and the tool sums the hours worked, separates regular from overtime hours, and estimates gross pay at your chosen wage rate — a quick way to check a timesheet.
Time From Now Calculator | Find Time After Or Before A Duration
Determines what time it will be after — or was before — a given duration. Enter a start time and the hours, minutes, and seconds to add or subtract, and the tool returns the resulting time, handling rollover across midnight and into the next or previous day.
Time to Decimal | Convert Hours to Decimal for Payroll
Converts hours and minutes into decimal hours for payroll and billing. Enter a time in hours, minutes, and seconds, or a full timesheet of clock-in and clock-out times, and the tool returns the decimal-hours value (for example, 8:30 becomes 8.5). Ideal for timesheets, freelance invoices, and payroll calculations.
Time Until Calculator | Show Live Countdown To Target Date/Time
Shows a live countdown to any target time or date. Enter the date and time you are waiting for — an event, deadline, or meeting — and the tool displays the remaining days, hours, minutes, and seconds, updating continuously until the moment arrives.
Time Zone Meeting Planner | Find the Best Meeting Time
Find a meeting time that works across every participant's time zone — enter the cities or zones, and the planner highlights the overlap in everyone's working hours on one grid. Handles daylight saving automatically, making international calls and remote-team syncs effortless.
Tire Size Calculator | Diameter, Revs & Speedo
A tire size calculator decodes metric tire codes (width/aspect/R rim) into overall diameter: rim inches × 25.4 + 2 × sidewall, where sidewall = width × aspect ÷ 100. It outputs diameter, sidewall height, revolutions per mile and the speedometer deviation versus a stock size.
Travel Budget Calculator | Plan Daily Trip Spending and Costs
Plan your trip budget in one place — fixed costs like flights and hotels plus a realistic daily spend, multiplied by trip length, with a contingency built in. See the total to save and the per-day figure to budget, before you start booking.
Voltage Drop Calculator | Estimate Voltage Drop and Percentage
Calculate voltage drop along a wire run from length, gauge, current and material — copper or aluminium — with the round-trip distance applied. Size wires correctly for safe, code-compliant electrical installations.
Wasiyyah Islamic Will Calculator | Compute max one-third bequest
The Wasiyyah (Islamic Will) calculator works out the maximum permissible bequest — one-third of the net estate after debts and funeral costs — and how much remains for the legal heirs.
Weight Calculator | Convert Pounds, Kilograms, Ounces, and Stones
Convert weight between pounds, kilograms, ounces, grams and stones instantly, with practical context for each figure. The complete unit converter for fitness, shipping, cooking and international travel.
Wind Chill Calculator | Get feels-like temp & frostbite risk
Calculates the wind chill, or feels-like temperature, on cold days. Enter the air temperature and wind speed, and the tool applies the National Weather Service wind chill formula to compute how cold the air actually feels on exposed skin, and includes the time to frostbite at that combination.
Years Ago Calculator | Find Date and Weekday N Years Earlier
Finds the exact date and day of the week any number of years in the past. Enter a number of years and an optional reference date, and the tool counts backwards accounting for leap years to return the resulting date, the weekday, and how many total days have passed.