Toolzie

Percentage Calculator

What is X% of Y?

What is % of ?
Result
0
0%100%
Formula (X ÷ 100) × Y

X is what % of Y?

is what % of ?
Percentage
0%
0%
Formula (X ÷ Y) × 100

% Increase / Decrease

From to ?
Change
0%
OriginalNew
Formula ((New − Original) ÷ Original) × 100

X is Y% of What?

is % of what?
Whole
0
Part (X)Whole
Formula (X ÷ Y%) × 100

How to Use the Percentage Calculator

Choose calculation type. Enter values. Get result instantly. Multiple calculation types.

Percentages constant—discounts, tips, grades, returns. Never memorize formulas.

Frequently Asked Questions

Four core types: X% of Y (find a percentage of a number), what % is X of Y (find the ratio), percent change (increase or decrease between two values), and reverse percentage (find the original number before a known percent change). Switch modes from the top of the calculator.
Enter the original value and the new value. The calculator returns the percent increase (positive) or decrease (negative) using the formula ((New − Original) / Original) × 100. Useful for price changes, salary raises, weight loss, and stock returns.
Yes. Decimals like 17.5% or 0.0825 are handled to full precision — no rounding until the final display. For financial calculations, the underlying math is double-precision, so a 0.001% difference won't compound into a measurable error.
((New − Original) / Original) × 100. If the result is positive, the new value is larger by that percent; if negative, smaller. Note: a 50% increase followed by a 50% decrease does NOT return to the original — it ends at 75% of the original (asymmetric by design).
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About This Tool

The Toolzie Percentage Calculator handles all common percentage problems: find what percent X is of Y, calculate percentage increase or decrease, find the original value before a percentage change, and more.

How to Use

  1. Select the type of percentage calculation you need.
  2. Enter the known values into the fields.
  3. Click Calculate to see the result instantly.
  4. Use the other modes to solve different percentage problems.

Frequently Asked Questions

How do I find what percentage 25 is of 200?

Select 'What percent is X of Y?', enter 25 for X and 200 for Y. The answer is 12.5%.

How do I calculate a 15% tip on $85?

Enter 85 as the original value and 15 as the percentage. The tip amount is $12.75.

How do I calculate percentage increase?

Select 'Percentage change', enter the original value and the new value — the calculator shows the percentage increase or decrease.

How do I find the original price before a discount?

Select 'Original value from percentage', enter the final value and the percentage off to find the original price.

Estimates only. Not tax, financial, or legal advice. Full disclaimer · Terms

Related Resources

Percentage calculations are everyday math: tips, discounts, taxes, and statistics. Top guides cover mental math and financial literacy.

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