Percent error calculator
Find how accurate your measurement or estimate is compared to the true value. Use absolute percent error for accuracy checks, or signed percent error when direction matters.
Calculator
Percent error will appear here.
Tip: results update as you type.
When to use each type
- Absolute percent error: shows how far off you are, always positive. Great for general accuracy checks and lab work.
- Signed percent error: keeps the sign, so you see whether your result is higher or lower than the true value. Useful for sensor calibration, forecasting, or model bias checks.
Examples
- Measured 10.2, True 10.0 → Absolute error = 2%; Signed error = +2% (reading high)
- Measured 9.8, True 10.0 → Absolute error = 2%; Signed error = –2% (reading low)
Excel and Google Sheets formulas
Assume your measured value is in A2 and the true value is in B2:
- Absolute percent error:
=ABS(A2 - B2) / ABS(B2) - Signed percent error:
=(A2 - B2) / ABS(B2)
Then format the result as a percentage.