Every percent is a fraction in disguise: 45% literally means 45 per hundred, or 45 ÷ 100. Converting a percent to a decimal just performs that division, which amounts to sliding the decimal point two places to the left — 45% becomes 0.45, 7% becomes 0.07, and 125% becomes 1.25. The move feels trivial until you skip it: multiplying $200 by 15 instead of 0.15 claims a $3,000 tip instead of $30, an error that has embarrassed many spreadsheet novices.

You need the decimal form before any calculator or formula will behave. Interest rates, tax rates, probabilities, and statistical margins all enter math as decimals: a 4.5% mortgage rate becomes 0.045 in the payment formula, and a 6% sales tax becomes 0.06. Going the other way is the mirror move — slide the point two places right and add the percent sign, so 0.45 becomes 45%. To convert with this tool, type the percent value in the first input box — for example, 45 — and type 0.01 in the second input box, since dividing by 100 is the same as multiplying by 0.01. The display shows 0.45.

With the pre-filled defaults — Percentage (%) 75% — the Percent to Decimal returns Decimal 0.7500000000, As Fraction (simplified) 0.7500. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.