Percentage Calculator

Four Types of Percentage Problems Solved

This calculator handles all four common percentage problem types with a single tool. Select the tab that matches your question:

X% of Y: "What is 15% of $200?" — common for tips, discounts, and taxes
% of Total: "30 is what percent of 200?" — for grades, shares, proportions
% Change: "What is the % change from 80 to 100?" — for growth rates, price changes
Increase by %: "What is 200 increased by 25%?" — for markups, salary increases

Percentage Formulas

X% of Y = (X / 100) × Y A is what % of B = (A / B) × 100 % Change = (New − Old) / |Old| × 100 Increase by X% = Value × (1 + X/100)

Common Percentage Calculations

Problem	Formula	Result
15% tip on $80	0.15 × 80	$12.00
20% discount on $150	150 × 0.80	$120.00
Sales tax 8.5% on $200	200 × 1.085	$217.00
Score: 42 out of 50	42/50 × 100	84%
Salary: $50k → $57.5k	(57.5-50)/50 × 100	+15%

Frequently Asked Questions

Subtract the original value from the new value, divide by the original value, then multiply by 100. Formula: ((New − Old) / Old) × 100. Example: From $80 to $100 is ((100 − 80) / 80) × 100 = 25% increase.

Percentage measures relative change; percentage points measure absolute change. If interest rates rise from 2% to 3%, that's 1 percentage point increase, but a 50% increase in the rate itself. This distinction is critical in finance and economics reporting.

To find the original value before a X% increase was applied: divide the final value by (1 + X/100). Example: A price is $120 after a 20% increase. Original = 120 / 1.20 = $100.

A basis point (bps) is 1/100th of a percentage point, or 0.01%. Used primarily in finance for interest rates, bond yields, and fee structures. A 25 basis point rate increase means 0.25%. One percentage point equals 100 basis points.