Percentage Calculator
Three quick percentage calculations — X% of a value, what percent one number is of another, and percentage change.
🔒 Calculated live in your browser — nothing is uploaded.
Everyday percentage maths
Three calculators in one: find a percentage of a value (15% of 200), work out what percent one number is of another (30 is what % of 200), and calculate percentage change between two numbers (200 → 250 = +25%). Each result updates live as you type. Everything runs in your browser.
Percentage change
Percentage change is the difference divided by the starting value, so going from 200 to 250 is +25%, and 250 back to 200 is −20% (the base changes, so the percentages differ).
Frequently asked questions
What is percentage change?
It measures how much a value grew or shrank relative to its starting point: (new − old) ÷ old × 100.
Why is an increase then decrease not symmetric?
Because the base differs. +25% from 200 is 250, but −20% from 250 returns to 200 — the same amount is a different percentage of a different base.
Is anything uploaded?
No. Calculations run entirely in your browser.