CalcaTools

Volume Calculator

A Volume Calculator is a free online tool that solves volume of a box using volume of a box, volume formula, volume of sphere. Students, teachers, and engineers use it to check homework, prep for exams, and verify hand calculations.

Last updated: July 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

Quick reference

ShapeFormula
Rectangular prisml × w × h
Cylinderπr²h
Sphere4/3πr³
Cone1/3πr²h

functions Shows the working, not just the answer

For students and teachers, the final number is only half the value. Every math tool here exposes the formula it applied, the intermediate steps, and the rounding rule, so you can follow along, check your homework, or use the answer in a proof or report with confidence.

calculate Accurate to the spec

Calculations use 64-bit floating point with sensible rounding for the domain (currency to 2 decimals, percentages to 4 decimals, algebra to 6 significant figures). Where exact rational arithmetic matters — fractions, factorials, simplification — we use a dedicated BigNumber path so 1/3 + 1/6 returns ½, not 0.49999.

school Free for classroom use

Educators are welcome to link to any math calculator on CalcaTools from a class site, Google Classroom, or worksheet. The pages are mobile-friendly, free, ad-supported (so we can keep them free) and have no sign-up wall — students just click and use them in class or at home.

tips_and_updates Pair with the spoke articles

Below the calculator we link a small set of plain-English explainer pages — "What is a percentage?", "Why does PEMDAS matter?", and so on. They cover the underlying concept in 4–6 short paragraphs. Read those before the calculator if the topic is new, or after if you want the extra context.

Interpretation guide

TipWhy
Use same unitsMixed units create wrong volumes
Cubic unitsVolume is always unit³
Round latePreserves accuracy

lightbulb Sizing a rectangular fish tank in gallons

An aquarium measures 48 in long, 18 in wide and 21 in tall. How many US gallons does it hold?

Result: About 78.5 US gallons. Volume = 48 × 18 × 21 = 18,144 cubic inches; divide by 231 (cubic inches per gallon) ≈ 78.5 gal.

What this means: Real stocking volume is lower once you subtract substrate, rocks and the gap below the rim — plan for roughly 90% of the calculated figure.

Formula & methodology

Formula: Volume depends on shape-specific dimensions

Volume measures three-dimensional space. Choose the formula that matches the solid and keep all dimensions in the same unit before calculating.

Frequently asked questions

How do I use the volume calculator?
Enter the requested values, review the instant result, then compare the reference table and interpretation guide below the calculator. Adjust one input at a time to see which assumption changes the result most.
What formula does the volume calculator use?
The calculator uses Volume depends on shape-specific dimensions and standard unit conversions or finance/statistics conventions where applicable.
Is the volume calculator accurate?
Results are estimates based on the values entered; check source data and assumptions before making decisions.
Why do my results differ from another calculator?
Different calculators may round differently, include extra assumptions, or use a different input frequency. Match the units, dates, tax assumptions, and rounding method before comparing outputs.
How do I find the volume of a prism?
Any prism is base area × height, whatever the base shape. A triangular prism with a base of ½ × 6 × 4 = 12 cm² and a length of 10 cm holds 120 cm³. The same rule covers boxes (rectangle base) and cylinders (circle base) — find the base area first and the rest is one multiplication.
How do I get the radius of a sphere or cone from its volume?
Invert the formula. Sphere: r = (3V ÷ 4π)^(1/3), so a 500 cm³ ball has r = 4.92 cm. Cone: r = √(3V ÷ πh) — a 400 cm³ cone that's 12 cm tall has a base radius of √(1200 ÷ 37.7) = 5.64 cm. The calculator handles the cube- and square-root steps for you.
How do I convert measurements in feet into cubic feet?
Multiply the three dimensions while they're all in feet: a 4 ft × 3 ft × 2.5 ft box is 30 cubic feet. If a dimension is in inches, divide it by 12 first — mixing feet and inches in one multiplication is the single most common volume mistake. Divide cubic feet by 27 for cubic yards or multiply by 7.48 for US gallons.