Percentage to Decimal Calculator

How it works

The word "percent" means per hundred. To convert a percentage to a decimal, divide by 100. This moves the decimal point two places to the left.

The formula

Why this works: A percentage expresses a quantity as parts per hundred. Dividing by 100 converts that "per hundred" scale to a decimal fraction of 1. This is the form needed for most calculations, such as finding a percentage of an amount or multiplying by a discount rate.

Worked examples

When to use this

Converting a percentage to its decimal form is an essential step before using it in most calculations. Spreadsheets, formulas, and calculators all require the decimal version rather than the percentage symbol.

• VAT calculations. To add 20% VAT to a net price of £240, multiply £240 by 0.2 to get the VAT amount (£48), or multiply by 1.2 to get the gross price (£288). The decimal form makes both steps straightforward in a spreadsheet or on a phone calculator.
• Discount pricing. A 15% discount on a £90 jacket requires multiplying by 0.15 (= £13.50 off). Alternatively, multiply by 0.85 (= 1 minus 0.15) to find the sale price of £76.50 in a single step.
• Compound interest. A savings account at 3.5% AER with £5,000 invested grows to £5,000 x 1.035 after year one. The decimal 0.035 is needed in the formula; the percentage symbol cannot be used directly.
• Exam paper weightings in spreadsheets. A GCSE subject where Paper 1 is worth 60% and Paper 2 is worth 40% requires weights of 0.6 and 0.4 in a SUMPRODUCT formula. Entering 60 and 40 without converting would give a result 100 times too large.
• Probability calculations. A probability of 35% must be expressed as 0.35 in any formula. When combining independent probabilities (for example, two separate 35% chances), you multiply the decimals: 0.35 x 0.35 = 0.1225, which is 12.25%.

Understanding the result

The decimal result is always the percentage divided by 100. Percentages below 100% produce decimals between 0 and 1. Percentages above 100% produce decimals above 1, which appear in growth factors and index values. For example, a year-on-year increase of 108% means a multiplier of 1.08.

Very small percentages produce decimals with leading zeros. Half a percent (0.5%) becomes 0.005, and a tenth of a percent (0.1%) becomes 0.001. These are easy to misread, so always double-check by reversing the conversion: 0.005 x 100 = 0.5%.

The decimal and percentage representations carry exactly the same information. The difference is purely one of format. Use the percentage form for communicating results to people; use the decimal form when feeding the value into a calculation.

Related concepts

• ➡ reverse any decimal back into a percentage in one step
• ➡ convert any fraction to a percentage by entering the top and bottom numbers
• ➡ apply the decimal form to find a percentage of another percentage

How to do this in Excel

In Microsoft Excel or Google Sheets, put the percentage value in cell A1, then enter this formula in B1:

Alternatively, if you format cell A1 as Percentage (Format Cells > Number > Percentage), Excel already stores the value as a decimal internally and displays it with a % sign. In that case, referencing the cell directly in a formula uses the decimal automatically, and you do not need to divide by 100 again.

How to do this without a calculator

Dividing by 100 is the same as moving the decimal point two places to the left. For whole-number percentages this is instant: 25% becomes 0.25, 7% becomes 0.07, and 100% becomes 1.00.

For percentages with a decimal point, apply the same shift. 4.5% becomes 0.045, and 12.75% becomes 0.1275. If the percentage is already a whole number but below 10, remember to insert a leading zero: 5% is 0.05, not 0.5.

A useful sanity check: if you then multiply your decimal by 100, you should get back to the original percentage. If 20% became 0.2, then 0.2 x 100 = 20. If the check does not match, you have moved the decimal the wrong number of places.

Common mistakes

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