Percentage Calculator

Calculate percentage increase or decrease between any two values. Our percentage increase calculator and percentage decrease calculator show the exact change with the formula used. Perfect for tracking price changes, stock performance, sales growth, and more.

Quickly calculate discount percentages and sale prices. Enter original and sale prices to find the discount percentage, or enter a discount to calculate the final price. Essential for shopping, retail pricing, and promotional planning.

Calculate your grade percentage from points earned and total points. Our grade percentage calculator works for tests, assignments, and overall course grades. Simply enter your score and the maximum possible score.

Convert between percentages, decimals, and fractions instantly. Our percentage to decimal calculator and decimal to percentage calculator show the conversion steps. Also includes fraction conversions for complete understanding.

A percentage is simply a fraction expressed out of 100, so the core formula is Percentage = (Part / Whole) × 100. The word "percent" comes from the Latin *per centum*, meaning "per hundred," which is why 50% and the fraction 50/100 describe the same amount.

Every percentage question rearranges the same three quantities: the part, the whole, and the percent. Knowing any two lets you solve for the third.

• Find the percent: (Part ÷ Whole) × 100

• Find the part: (Percent ÷ 100) × Whole

• Find the whole: (Part × 100) ÷ Percent

Because these are timeless arithmetic identities, they never change year to year. Educational resources such as Khan Academy explain the same base-100 relationship used here.

To use the calculator, first pick the calculation type that matches your question, then enter your two values. The tool instantly returns the answer plus the step-by-step formula so you can check the logic yourself.

Suppose a jacket costs $80 and is marked 25% off. Choose "Decrease by X%," enter 25 and 80, and you get $60.

• Step 1: Select the calculation type from the dropdown.

• Step 2: Enter the first value (the percent or base number).

• Step 3: Enter the second value and read the result, decimal, and fraction outputs.

Working a problem by hand: 25% of 80 = 0.25 × 80 = $20 off, so $80 − $20 = $60 final price. The Consumer Financial Protection Bureau (CFPB) encourages this kind of quick verification before any purchase or contract.

The most frequent error is dividing by the wrong number — using the new value instead of the original as the base when finding percentage change. Always divide by the starting (old) value.

Small setup mistakes can produce answers that are off by a large margin, especially with money.

• Reversing part and whole: "25 is what percent of 200" is 12.5%, not 800%.

• Averaging two percentages directly when the bases differ, which distorts the true combined rate.

• Forgetting that a percentage increase then an equal percentage decrease does not return to the start — a 50% rise followed by a 50% cut leaves you below the original.

• Confusing percentage points with percent change (covered in a section below).

For financial decisions, the CFPB and FINRA both recommend re-checking the base value before trusting any percentage result.

Percentage change measures how much a value has grown or shrunk relative to its starting point: ((New − Old) / Old) × 100. A positive result is an increase; a negative result is a decrease.

Inflation is a real-world use of this formula. Agencies measure it by comparing a price index across two periods rather than any single item.

• Old value: the earlier price or index level.

• New value: the current price or index level.

• Result: the percent the price has risen or fallen over that span.

The U.S. Bureau of Labor Statistics (BLS) calculates the Consumer Price Index this way, and the Federal Reserve references such year-over-year percentage changes when discussing its inflation goals. Because index values are revised over time, always pull the current figures from BLS rather than relying on a memorized number.

To add sales tax, multiply the price by the tax rate as a decimal and add it back: Total = Price × (1 + Rate/100). An 8% tax on a $50 item adds $4, for a $54 total.

Sales tax rates are set by state and local governments and change periodically, so confirm your current local rate rather than assuming a fixed figure.

• Tax amount: Price × (Rate ÷ 100)

• Reverse a rate: (Tax Paid ÷ Price) × 100

• Tip: Bill × (Tip% ÷ 100), commonly 15–20% of the pre-tax bill.

The Internal Revenue Service (IRS) handles federal income tax rather than retail sales tax, and the CFPB offers guidance on reading receipts and added fees. This calculator handles the arithmetic; use your jurisdiction's published current rate for the input.

A percentage return shows profit or loss relative to what you originally invested: ((Ending Value − Starting Value) / Starting Value) × 100. Buying at $80 and selling at $100 is a 25% return.

Returns can be positive or negative, and a large percentage gain on a small base is not the same as real dollars earned.

• Starting value: your original cost or investment.

• Ending value: the current or sale value.

• Result: the percent gained or lost.

The U.S. Securities and Exchange Commission (SEC) and FINRA caution that past percentage returns do not guarantee future results and that fees reduce your true return. For long-horizon comparisons, distinguish a simple total return from an annualized rate, which spreads growth across the number of years held.

A percentage point is the plain arithmetic gap between two percentages, while percent change is that gap relative to the starting percentage. If a rate rises from 5% to 6%, that is a 1 percentage-point increase but a 20% relative increase.

Confusing the two is one of the most common reporting errors in finance and news.

• Percentage points: 6% − 5% = 1 point (simple subtraction).

• Percent change: (6 − 5) ÷ 5 × 100 = 20%.

The distinction matters most with interest rates and unemployment figures. The Federal Reserve describes rate moves in percentage points (or basis points, where 100 points = 1 percentage point), and the Bureau of Labor Statistics (BLS) reports labor-rate shifts the same way. When you see a headline about a rate change, check which measure is being used before drawing conclusions.