Percentage Calculator

Solve any percentage problem: % of, ratio, increase and decrease.

What is X% of Y?

X is what percent of Y?

Percentage change from X to Y

What Does the Percentage Calculator Do?

This calculator solves the three percentage problems everyone meets, each in its own panel with live results: What is X% of Y? (15% of 200 = 30), X is what percent of Y? (30 is 15% of 200) and percentage change from X to Y (80 → 100 is a 25% increase). No mode switching or formula memorization — type the two numbers you have and read the answer.

How to Use the Calculator

  1. Find the panel matching your question.
  2. Enter your two numbers — the result appears as you type.
  3. For percentage change, the result is labeled as an increase or decrease automatically.

The Three Formulas, Demystified

  • X% of Y = X ÷ 100 × Y — tips, taxes, discounts: 18% tip on a $64 bill = 11.52.
  • X as a % of Y = X ÷ Y × 100 — scores and proportions: 42 correct out of 60 = 70%.
  • Change from X to Y = (Y − X) ÷ |X| × 100 — growth and drops: traffic from 8,000 to 9,200 = +15%.

One classic trap the third panel prevents: percentage change is always measured against the starting value. A price that rises 50% then falls 50% does not return to the start — it ends 25% below it, because the second 50% is taken of a bigger number.

Frequently Asked Questions

What is the difference between percentage change and percentage points?

If a rate moves from 40% to 44%, it rose 4 percentage points but 10 percent (4 is 10% of 40). Use points when comparing two percentages directly, percent when describing relative growth.

How do I calculate a reverse percentage (price before tax)?

Use the second panel conceptually: if 120 includes 20% tax, the original is 120 ÷ 1.20 = 100. For dedicated add/remove tax math, our GST/VAT Calculator does exactly this.

Why is percentage decrease capped at 100%?

A 100% decrease means reaching zero — nothing positive can decrease by more than 100%. Increases, by contrast, are unlimited: tripling is a 200% increase.

Can I use decimals and negative numbers?

Yes — all panels accept decimals, and the change panel handles negative starting values correctly by measuring against the absolute value.