Percentage Calculator

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Solve percentage increases, decreases, fractions, and discounts.

1. Percentage of a Number

What is% of

(15 ÷ 100) × 25037.50

2. Percentage Proportion

is what % of

(45 ÷ 180) × 10025.00%

3. Percentage Change (Growth / Decay)

Fromto

Difference: +40+50.00%

4. Increase or Decrease Value

500 × 1.20600.00

5. Reverse Percentage (Pre-Tax Base)

Total with taxat% rate

Tax amount: $20.00Pre-tax: $100.00

6. Profit Margin vs Markup

Cost: $Selling Price: $

Profit: $40

Margin: 40.00%Markup: 66.67%

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All computation executes exclusively inside your device memory using Web APIs and WebAssembly. No data or files ever leave your browser.

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Zero network roundtrips. Operates offline without sending external API requests, delivering instantaneous sub-millisecond computation.

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Engineered with RFC standards, cryptographic primitives (Web Crypto Subtle API), and production-grade formatting libraries.