Herramientas Web

Percentage calculator

Pick what you want to calculate, enter the values, and get the result right away, with the step-by-step formula and a link to share the calculation.

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How it is calculated

Formula
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Quick calculators

Fill in any phrase without switching modes. Results show up right away.

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    Step by step

    How to use it

    1. Pick the type of calculation: percent of a number, what percent one value is, increase or decrease, percent change, error, successive percentages, or conversions.
    2. Enter the values in the fields. Use a period for decimals and choose how many decimal places to show.
    3. The result appears right away, with the formula and your values filled in. Copy it with one click.
    4. Use the quick calculators to solve other phrases without switching modes, or copy the link to share the calculation.
    FAQ

    Frequently asked questions

    How do you calculate a percentage of a number?

    Multiply the number by the percentage and divide by 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30.

    How do I find what percent one number is of another?

    Divide the part by the total and multiply by 100. If 30 is part of 200, then 30 ÷ 200 × 100 = 15%.

    How do I calculate a discount or an increase?

    For a discount, multiply the price by (1 − percentage ÷ 100). For an increase, multiply by (1 + percentage ÷ 100). A 20% discount on 1,500 gives 1,500 × 0.8 = 1,200. Use the “Add or subtract a %” mode, which also shows the breakdown.

    What is the difference between percentage points and percent?

    If a rate goes from 10% to 12%, it rises 2 percentage points, but its relative change is 20% (2 ÷ 10). The “Percentage points” mode calculates both.

    Why do discounts of 20% and 10% not add up to 30%?

    Because the second discount applies to the price that already dropped. On 1,000, 20% off leaves 800, and 10% off 800 leaves 720: the total discount is 28%. The “Successive” mode works this out for any number of percentages.

    Are the numbers I enter saved?

    No. The calculations run in your browser and are not sent or stored anywhere. Only the last mode and the number of decimals are remembered; your values travel in the link only if you copy it.

    The formulas you need

    • Percent of a number: result = percentage ÷ 100 × number.
    • What percent one value is: percentage = part ÷ total × 100.
    • Increase or decrease: result = value × (1 ± percentage ÷ 100).
    • Percent change: change = (final value − initial value) ÷ initial value × 100.
    • Find the total: total = part ÷ (percentage ÷ 100).
    • Percent error: error = |measured − exact| ÷ |exact| × 100.

    Worked examples

    • 15% of 200: 200 × 15 ÷ 100 = 30.
    • What percent 30 is of 200: 30 ÷ 200 × 100 = 15%.
    • From 200 to 230: (230 − 200) ÷ 200 × 100 = +15%.
    • Error of a measurement: if the exact value is 10 and you measured 9.8, the error is 0.2 ÷ 10 × 100 = 2%.

    An example with prices

    A product costs 4,800 and is 15% off. The discount is 4,800 × 15 ÷ 100 = 720, so you pay 4,800 − 720 = 4,080. If the same product later goes from 4,080 to 4,500, the change is (4,500 − 4,080) ÷ 4,080 × 100 ≈ 10.29%.

    Decimal, percent, and fraction

    0.25 is the same as 25% and as 1/4. To go from a decimal to a percent, multiply by 100; to go from a percent to a decimal, divide by 100. Other handy equivalents: 0.5 = 50% = 1/2, 0.125 = 12.5% = 1/8, and 0.05 = 5% = 1/20.

    Quick mental math

    With a value of 850: 10% comes from moving the decimal point one place (85), 5% is half of that (42.5), 15% is the two added together (127.5), 20% is double the 10% (170), 25% is a quarter (212.5), and 50% is half (425). The “Common percentages” table in the tool works these out for any number.

    Adding and removing a tax

    To add a 20% tax to 10,000, multiply by 1.2: the result is 12,000. To go the other way, divide by 1.2. Do not subtract 20% from 12,000, because you would get 9,600 instead of 10,000. The rule holds for any percentage: you get the initial value back by dividing by (1 + percentage ÷ 100). For a percentage charged every month on a debt, such as the interest on a loan, use the loan calculator.

    Common mistakes

    • Going up and down by the same percentage: if 100 rises 20% it reaches 120, and if it then drops 20% it ends at 96, not 100.
    • Getting back to the original value: after a 50% increase you need a 33.3% decrease, not 50%, because the base changed.
    • Adding discounts: 20% and then 10% equal 28%, not 30%. Use the “Successive” mode.
    • Mixing up percentage points and percent: a rate that goes from 10% to 12% rises 2 percentage points, which in relative terms is 20%.

    Updated on September 29, 2026