AnyCalc

Finance & Math

Percentage Calculator

Calculate percentages, increases, and decreases

Reviewed: AnyCalc Editorial|2026-07-19|Editorial policy|About

What this calculator does

A percentage calculator handles the most common percentage calculations people encounter in daily life: finding what percent one number is of another, calculating a percentage of a number, and determining percentage increase or decrease between two values. The three core formulas are: (1) What is X% of Y? → Result = Y × X / 100, (2) X is what percent of Y? → Percent = X / Y × 100, (3) Percentage change from X to Y → Change = (Y − X) / X × 100. These calculations appear everywhere — calculating tips at restaurants, figuring out sale discounts, understanding tax rates, computing grade percentages, analyzing investment returns, and interpreting statistics. For example, finding 15% tip on a $45 meal ($6.75), determining that 35 out of 50 correct answers is 70%, or seeing that a price drop from $80 to $60 is a 25% decrease. This calculator handles all percentage scenarios in one place, with clear step-by-step explanations of each calculation. It also includes a reverse percentage function — if something costs $68 after a 15% discount, the original price was $80 — which is useful for negotiating and verifying sale prices.

Percentage Calculator

How to use

  1. 01
    Choose a mode
    Select the type of percentage calculation you need from the available options.
  2. 02
    Enter your values
    Input the numbers for your calculation.
  3. 03
    Get the answer
    View the result instantly along with the formula used.

Percentage Calculator FAQ

How do I calculate percentage increase?▾
Use the formula: Percentage Increase = (New Value − Old Value) / Old Value × 100. For example, if a stock price rose from $40 to $52, the increase is ($52 − $40) / $40 × 100 = 30%. The same formula works for percentage decrease — a negative result indicates a decline.
How do I find what percentage one number is of another?▾
Divide the part by the whole and multiply by 100. If you scored 42 out of 60 on a test, your percentage is 42 / 60 × 100 = 70%. This works for any "X is what percent of Y" question — just put X over Y and multiply by 100.
How do I calculate the original price before a discount?▾
Divide the discounted price by (1 − discount rate). If an item costs $68 after a 15% discount, the original price was $68 / (1 − 0.15) = $68 / 0.85 = $80. This reverse percentage calculation is useful for verifying that sale prices represent genuine discounts.
Why is the percentage decrease from 100 to 50 different from the increase from 50 to 100?▾
Because percentage change is relative to the starting value. Going from 100 to 50 is a 50% decrease (50/100), but going from 50 to 100 is a 100% increase (50/50). The base number matters, which is why you should always clarify what the percentage is relative to when comparing changes.

Interpret carefully

Outputs are decision-support estimates, not a substitute for professional judgment.

  • Treating Percentage Calculator output as a final professional diagnosis, quote, or legal determination
  • Entering approximate values when the result is sensitive to units or precision
  • Applying the FAQ answer (“How do I calculate percentage increase?”) to a special case without checking assumptions

Next steps

  1. Double-check inputs against your source documents (labs, statements, specs, or notes).
  2. Confirm the method below matches your use case before you act on the number.
  3. For medical, financial, or production decisions, verify with a qualified professional.

Disclaimer: Results are informational only and do not constitute medical, financial, legal, or professional advice. Report issues: sublimernj@gmail.com

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