Year Over Year Change Calculator
Last updated: July 2026 · Free · No sign-up required
Enter values above and click Calculate to see your result instantly.
Inside the Year Over Year Change Calculator
Behind the inputs above sits one rule: YoY % = (current − previous) ÷ |previous| × 100. The tool evaluates it instantly with the values you enter.
If you are new to year over year change calculator, start with the worked example in the methodology section below — it walks the formula end-to-end with real numbers — then use the quick-reference table for common scenarios.
Quick reference
| Previous | Current | YoY |
|---|---|---|
| 100 | 115 | +15% |
| 200 | 180 | −10% |
| 50,000 | 62,500 | +25% |
| 1.2M | 1.5M | +25% |
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
| YoY growth | Context (revenue) |
|---|---|
| 0–5% | Mature/inflation-level growth |
| 5–15% | Healthy expansion |
| 15–40% | High growth |
| > 40% | Hypergrowth — rarely sustainable |
Formula & methodology
Formula: YoY % = (current − previous) ÷ |previous| × 100
- Enter last year’s value and this year’s value for the same period (full year, same quarter, same month).
- The tool subtracts for the absolute change and divides by the previous value for the percentage.
- The growth multiple (current ÷ previous) is shown for quick compounding maths.
Example: 100 → 115 is +15 absolute, +15% YoY, a 1.15× multiple.
Frequently asked questions
Explore the full percentage & discount toolkit
Every CalcaTools percentage calculator — percent-of and percent-off math, stacked discounts, retail markup and margin, error and accuracy checks, plus year-over-year change and ratios — with the working shown on every result.