Percentage Calculator

How to Calculate Percentages

A percentage is a fraction of 100 — "per cent" literally means "per hundred." The core formula behind every percentage calculation is: part ÷ whole × 100 = percentage. This one relationship, rearranged, solves every common percentage problem: finding a percentage of a number, working out what percentage one number is of another, calculating percentage change, or adjusting a number by a percentage.

The Four Calculators Explained

X% of Y answers questions like "what is 15% of 200?" — used constantly for tips, discounts, tax, and commission. The formula is (X ÷ 100) × Y. X is what % of Y flips the question around: "30 is what percent of 200?" — useful for test scores, budget shares, and completion rates. The formula is (X ÷ Y) × 100. Percentage increase/decrease tells you how much something changed in relative terms, using ((New − Old) ÷ Old) × 100 — essential for tracking price changes, salary raises, or performance metrics. Add/subtract a percentage applies a percentage change to a starting number, such as adding 20% VAT or applying a 15% discount.

Frequently Asked Questions

Why is percentage change calculated from the "old" value?

Percentage change is always relative to the starting point, because that reflects the actual proportional change experienced. A price rising from €80 to €100 is a 25% increase, but if it then fell back from €100 to €80, that would be a 20% decrease — not 25% — because the base changed. This asymmetry surprises many people the first time they encounter it.

What's the difference between percentage points and percent?

If an interest rate rises from 5% to 7%, that is a 2 percentage point increase, but a 40% relative increase (2 ÷ 5 × 100). Percentage points measure the raw difference between two percentages; percent measures the relative change. Mixing these up is a common source of confusion in financial and statistical reporting.

How do I calculate a percentage discount at checkout?

Use the Add/Subtract tab with a negative percentage — for a 20% discount on a €50 item, enter 200... actually enter 50 as the number and −20 as the percentage to get the discounted price directly.