Percent Calculator

Calculate percentages, percentage change, discounts, increases, decreases, and ratios in one focused tool.

Calculation type

What is B% of A?

Find the percentage amount from a base number.

Example: 20% of 5,000 = 1,000

Base numberPercentage

Decimal places

Result

1,000

5,000 * 20% = 1,000

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What is the percent calculator?

This calculator covers everyday and business percentage calculations: discounts, tips, taxes, fees, growth rate, ratio, achievement rate, portfolio return, and budget allocation. It supports 6 calculation types with live results, presets, decimal-place controls, copy, and recent history.

Six percentage calculation types

Core formulas

B percent of A: result = A x (B / 100). Example: 20% of KRW 50,000 is KRW 10,000.
A plus B percent: result = A x (1 + B / 100). Example: KRW 10,000 + 10% = KRW 11,000.
A minus B percent: result = A x (1 - B / 100). Example: KRW 50,000 - 30% = KRW 35,000.
A is what percent of B: result = (A / B) x 100. Example: 85 is 85% of 100.
Change rate: result = ((current - previous) / previous) x 100. Example: 1,000 to 1,200 is 20% increase.
Part-to-whole ratio: result = (part / whole) x 100. Example: KRW 300,000 of KRW 1,000,000 is 30%.

Source examples

A KRW 89,000 item with 30% discount costs KRW 62,300 because 89,000 x 0.70 = 62,300.
A 15% tip on a KRW 45,000 meal is KRW 6,750, making total payment KRW 51,750.
Sales rising from KRW 85,000,000 to KRW 102,000,000 is 20% growth.
Margin and markup differ: with cost KRW 7,000 and selling price KRW 10,000, margin is 30% and markup is 42.9%.

Common percentage traps

Interpretation rules

Percent comes from Latin per centum, meaning per hundred. 50% is 50 out of 100, or 1/2, or 0.5.
Percent and percentage points differ. If interest rises from 5% to 7%, that is +2 percentage points or a 40% relative increase.
Sequential discounts multiply. A 20% discount followed by 10% discount leaves 100% x 80% x 90% = 72%, so total discount is 28%, not 30%.
Increasing by 50% and then decreasing by 50% does not return to the original value: 100 becomes 150 and then 75.
VAT-inclusive price divided by 1.1 gives supply value in a 10% VAT system: KRW 11,000 / 1.1 = KRW 10,000 and VAT is KRW 1,000.
In tax or financial calculation, round only at the final result unless a law or contract requires a specific rounding or truncation rule.