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Percentage Calculator

Find percentages, increases and decreases.

Best for: Use it for discounts, tips, tax, grades, commission, or measuring growth between two figures.

Complete guide

Input

Result

20% of 150 = 30
Standard formula Private — runs in your browser, no account

What to do next

Next: BMI Calculator
More about this result
Result quality
Type
Exact Formula
Method
Standard mathematical formula
Confidence
High

A precise, deterministic calculation - the same inputs always give exactly this result.

What this means

The result answers one of the three percent questions. For percentage change, the sign matters — positive is an increase, negative a decrease — and the base is always the original (old) value.

3 Important insights
  • Everything runs in your browser — nothing is uploaded or stored.
  • Change any input to see how the result responds instantly.
  • Results are estimates for general guidance, not professional advice.
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How it's calculated & sources
The Percentage Calculator uses the standard method for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

A% of B = B × A/100 · A is what % of B = A/B × 100 · Change = (B − A)/A × 100 · Increase/decrease = A × (1 ± B/100)

Continue your journey

Where people usually head next.

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BMI Calculator
Calculate your Body Mass Index in seconds.

Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Percentage?
A percentage calculator handles the everyday percent questions: what is X% of Y, X is what percent of Y, the percentage change between two numbers, and increasing or decreasing a number by a percent.
Why does Percentage matter?
The result answers one of the three percent questions. For percentage change, the sign matters — positive is an increase, negative a decrease — and the base is always the original (old) value.
How is Percentage calculated?
A percent is a fraction of 100. 'X% of Y' multiplies Y by X/100; 'X is what % of Y' divides X by Y and multiplies by 100; percentage change divides the difference by the original value. Formula: X% of Y = Y × X/100 | % change = (New − Old) ÷ Old × 100.
What is a good percentage?
Note the difference between a percentage and a percentage point: going from 10% to 12% is a 2 percentage-point rise but a 20% relative increase.
What are common percentage mistakes?
Using the new value (not the original) as the base when computing percentage change.
When should you use the Percentage Calculator?
Use it for discounts, tips, tax, grades, commission, or measuring growth between two figures.

What is the Percentage Calculator?

A percentage calculator handles the everyday percent questions: what is X% of Y, X is what percent of Y, the percentage change between two numbers, and increasing or decreasing a number by a percent.

How the Percentage Calculator works

A percent is a fraction of 100. 'X% of Y' multiplies Y by X/100; 'X is what % of Y' divides X by Y and multiplies by 100; percentage change divides the difference by the original value.

X% of Y = Y × X/100 | % change = (New − Old) ÷ Old × 100

What's a typical value?

Note the difference between a percentage and a percentage point: going from 10% to 12% is a 2 percentage-point rise but a 20% relative increase.

Common percentages of a value

50512.52537.5
10010255075
2002050100150
50050125250375
1,000100250500750

Worked example

15% of 240 = 240 × 0.15 = 36 Going from 80 to 100 = (100 − 80) ÷ 80 × 100 = 25% increase

Common mistakes to avoid

  • Using the new value (not the original) as the base when computing percentage change.
  • Confusing percentage points with percent — they answer different questions.
  • Reversing a discount incorrectly: adding back the same percent does not recover the original price.

Keywords: percent.

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Percentage Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Percentage Calculator?+

Percentage Calculator uses the standard percentage formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Percentage Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Percentage Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Reddit post
Title: I built/used this free percentage calculator — instant, no signup

Body: Find percentages, increases and decreases. Try it: https://freetoolsgalaxy.com/tools/percentage-calculator
LinkedIn post
Percentage Calculator on Free Tools Galaxy — Find percentages, increases and decreases. https://freetoolsgalaxy.com/tools/percentage-calculator
Medium intro
# Percentage Calculator — the free tool I keep coming back to

Find percentages, increases and decreases.

Try it: https://freetoolsgalaxy.com/tools/percentage-calculator
Quora answer
The fastest way is to use a free in-browser percentage calculator: https://freetoolsgalaxy.com/tools/percentage-calculator. Find percentages, increases and decreases.

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<iframe src="https://freetoolsgalaxy.com/tools/percentage-calculator?embed=1" title="Percentage Calculator" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
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<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="ftg-embed-height"){document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source){f.style.height=e.data.height+"px";}});}});</script>
<p><a href="https://freetoolsgalaxy.com/tools/percentage-calculator" target="_blank" rel="noopener">Powered by Percentage Calculator on Free Tools Galaxy</a></p>
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<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/percentage-calculator?embed=1" title="Percentage Calculator" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
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[Percentage Calculator — free online tool](https://freetoolsgalaxy.com/tools/percentage-calculator)

<iframe src="https://freetoolsgalaxy.com/tools/percentage-calculator?embed=1" width="100%" height="600" frameborder="0"></iframe>
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<a href="https://freetoolsgalaxy.com/tools/percentage-calculator" target="_blank" rel="noopener">Try the free Percentage Calculator</a>

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Title
I built a free word counter that works instantly in the browser — no signup, no ads in your face
Body
Hey r/[subreddit],

I kept needing a quick word counter and most options online were slow or behind paywalls, so I built one that:

• Runs 100% in your browser (your data never leaves your device)
• No signup, no email wall, no popups
• Loads in under a second on mobile

It covers the standard word counter use cases (count, words, characters) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/word-counter

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