What is percent error?

Percent error = |measured value - actual value| / |actual value| × 100. It expresses how far a measurement is from the true value.

What if actual is zero?

When actual is zero, percent error is undefined (division by zero). We show an error in that case.

Calculate percent error between measured and actual (or accepted) value. Percent error = |measured - actual| / actual × 100.

Measured value

Actual (accepted) value

What is percent error?: Percent error = |measured value - actual value| / |actual value| × 100. It expresses how far a measurement is from the true value.
What if actual is zero?: When actual is zero, percent error is undefined (division by zero). We show an error in that case.

Celsius to Fahrenheit Converter

Convert Celsius to Fahrenheit and Fahrenheit to Celsius instantly. Free temperature converter.

Tip Calculator

Calculate tip and split the bill. Enter bill amount, tip percentage, and number of people.

Roman Numeral Converter

Convert numbers to Roman numerals and Roman numerals to numbers. Supports 1–3999.

Combinations Calculator

Calculate C(n,r) — the number of ways to choose r items from n without order. Uses n!/(r!(n-r)!).

Combinations with Replacement Calculator

Calculate the number of ways to choose r items from n with repetition allowed. Formula: C(n+r-1, r).

Even Permutations Calculator

Count how many permutations of n objects are even (expressible as an even number of swaps). For n ≥ 2, equals n!/2.