Is a 50% increase followed by a 50% decrease back to the original?

No — this trips up most people. $100 → +50% → $150 → −50% → $75. Percent changes compound multiplicatively (1.5 × 0.5 = 0.75), not additively. Anytime you stack percents, multiply the factors.

How is percent change different from percentage points?

If interest rates move from 4% to 5%, that's a 1-percentage-point rise but a 25% percent change. Journalists and finance pros use 'percentage points' to avoid this ambiguity. The tool reports percent change; translate to points if needed.

Can I reverse a percent discount (find the original price)?

Yes — use the discount calculator's reverse mode. If a sale price is $70 after 30% off, original = $70 ÷ 0.7 = $100. The math is one divided by the retained fraction, not plus 30%.

Why do my tip + tax results differ between apps?

Order of operations. Tax on the pre-tip subtotal, then tip on pre-tax or post-tax subtotal — all three are valid and all three produce different totals. US convention is tip on pre-tax.

Money & Finance · Free tool

Percentage Calculator

Calculate percent of a number, percent change, and add or subtract percentages instantly. Free online tool with a clean, mobile-friendly interface for quick math.

Updated June 2026

What is X% of Y?

X (percent)Y (value)

Result: —

X is what % of Y?

X (part)Y (whole)

Result: —%

Percent change from X to Y

X (start)Y (end)

Result: —

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What it does

A fast percentage calculator that covers the three formulas that actually come up in daily life: “what is X% of Y”, “A is what percent of B”, and “percent change from old to new”. All three are live on the page — fill the one you need. Negative results show red so a price drop or account loss reads at a glance.

For tip and bill-split math specifically, use the Tip Calculator. For a written walkthrough of five common formulas, including markup and reverse percent, see How to calculate percentages.

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Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.

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Example input & output

Input

Card 1: What is 15% of 300?
Card 3: From 200 to 260

Output

Card 1 answer: 45
Card 3 answer: +30% change

Negative results are shown in red so a price drop or portfolio loss is visually unmistakable.

How to use it

Use the first card for “what is X% of Y” — enter two numbers.
Use the second for “A is what % of B”.
Use the third for percent change — negative means a drop.
Numbers update as you type; nothing to submit.

When to use this tool

Quick tip math (15% of $48) or tax math (8.5% of $249).
Checking percent change on a KPI, stock price, or weight — the third card handles before/after.
Converting a raw score to a percentage grade (42 out of 50 = what %).
Sanity-checking a discount that advertises an ambiguous save amount.

When not to use it

Compounded percent changes over multiple periods — use the compound interest calculator (stacked percents don't add).
Margin vs markup business math — use the profit margin calculator (they're different base formulas).

Frequently asked questions

Is a 50% increase followed by a 50% decrease back to the original?: No — this trips up most people. $100 → +50% → $150 → −50% → $75. Percent changes compound multiplicatively (1.5 × 0.5 = 0.75), not additively. Anytime you stack percents, multiply the factors.
How is percent change different from percentage points?: If interest rates move from 4% to 5%, that's a 1-percentage-point rise but a 25% percent change. Journalists and finance pros use 'percentage points' to avoid this ambiguity. The tool reports percent change; translate to points if needed.
Can I reverse a percent discount (find the original price)?: Yes — use the discount calculator's reverse mode. If a sale price is $70 after 30% off, original = $70 ÷ 0.7 = $100. The math is one divided by the retained fraction, not plus 30%.
Why do my tip + tax results differ between apps?: Order of operations. Tax on the pre-tip subtotal, then tip on pre-tax or post-tax subtotal — all three are valid and all three produce different totals. US convention is tip on pre-tax.

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