How to use this calculator
Choose decimal places, significant figures, or error. Enter a measured value and the accepted reference for error.
Formula and method
Absolute error = |measured−accepted|; relative error = absolute error/|accepted|. A rounded result at scale q has a half-unit interval of width q.
Worked example
12.345 to 2 decimal places is 12.35; measured 12.5 versus accepted 12 has absolute error 0.5.
Assumptions and supported scope
Halfway ties round away from zero. Places −12 to 12; 1–15 significant figures, with decimal scale limited to −12..15. Input decimal ties use the stated rule; displayed results and interval endpoints use double precision and can be approximate.
Method references
Method and worked example checked against the calculator implementation. About our methods · Report a correction