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Percentage Checker

Use this percentage checker to calculate common % questions in seconds: X% of Y, A is what % of B, % change, and reversing an increase/decrease to find the original value.

Category: Finance · URL: /tools/percentage-checker.html
Tip: You can paste numbers with commas (e.g., 1,234.56). Percent signs are optional.
Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Select a calculation type, enter the required numbers, then press Calculate.

  1. Choose a mode (e.g., X% of Y or Percent change).
  2. Enter values (you can paste numbers with commas).
  3. Pick decimal rounding if needed.
  4. Click Calculate, then Copy to paste elsewhere.
Keywords this page targets (natural cluster): percentage checker, calculate percentage of a number, x percent of y, what percent is a of b, percentage increase calculator, percentage decrease calculator, percent change calculator, reverse percentage calculator, find original price before discount, percentage difference vs change, percent to decimal quick check, discount percentage checker, markup percentage calculation, calculate tax percentage, percentage formula calculator, how to find percentage, percent change from old to new, increase number by percentage, decrease number by percentage, percentage of total calculator, find percentage from two numbers, percentage rounding
Secondary intents covered: Calculate a discount amount from a percentage and price, Find what percent one value is of another, Check percent increase/decrease between two values, Compute a new value after applying a percent change, Reverse a percent increase/decrease to get the original value, Validate percentages in invoices, budgets, or reports, Quickly copy the result for spreadsheets or emails, Round results to a chosen number of decimals

FAQ

How do I calculate X% of Y?

Use X% of Y mode. The formula is (X/100) × Y.

How do I find what percent A is of B?

Use A is what % of B. It calculates (A ÷ B) × 100.

What’s the formula for percent change?

Percent change is (new − old) ÷ old × 100. If old is 0, percent change isn’t defined.

How do I increase or decrease a number by a percentage?

Use Increase/Decrease a value by %. It applies value × (1 ± p/100).

How do I find the original value before a discount or markup?

Use Find original before % increase/decrease. It calculates original = final ÷ (1 ± p/100).

Why is my percent change negative?

A negative result means the new value is lower than the old value (a decrease).

Can I enter commas or a % sign in the inputs?

Yes. The tool accepts commas (e.g., 1,234.56) and an optional percent sign (e.g., 25%).