Enter what you measured and the accepted or true value. Percent error is the size of the difference as a percentage of the true value, so it tells you how far off your result was.
Percent error = |measured − true| ÷ |true| × 100%. Measuring g as 9.62 m/s² when the accepted value is 9.81 m/s² gives |9.62 − 9.81| ÷ 9.81 × 100 = 1.94%.
The absolute error is just the size of the difference in the original units (0.19 m/s² here), and the relative error is the same thing as a fraction (0.0194). The signed version keeps the direction: a negative result means your measurement was too low, a positive one means it was too high.
Percent error is different from percentage change. Percent error always compares against a known correct value; percentage change compares an old value with a new one.
Percent error = |measured − true| ÷ |true| × 100. Take the difference between your result and the accepted value, ignore its sign, divide by the accepted value and multiply by 100.
The usual definition uses the absolute value, so it is never negative. Some classes use a signed version to show whether the measurement was too high (positive) or too low (negative); both are shown here.
It depends on the experiment. In school labs, under about 5% is often considered good; precise instruments may aim for well under 1%. Always compare with the uncertainty of your equipment.
Absolute error is the raw difference in the measurement’s units. Relative error divides that by the true value, giving a unitless fraction that can be compared across different quantities.
Because it would mean dividing by zero. In that case, report the absolute error instead.
