Significant Figures Calculator
Count the significant figures in any number and round it to the sig figs your lab report requires.
Significant figures
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Rounded —
Scientific notation —
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How it works
Rules: non-zero digits count; zeros between digits count; leading zeros never count; trailing zeros count only with a decimal pointFrequently Asked Questions
How do I count significant figures?
All non-zero digits count; zeros sandwiched between digits count; leading zeros never count (0.0045 has 2); trailing zeros count only when a decimal point is present (120. has 3, 120 is ambiguous — usually treated as 2).
How do I round to 3 significant figures?
Keep the first three significant digits and round the third by the next digit: 0.048627 → 0.0486; 52,691 → 52,700. Scientific notation removes all ambiguity.
Why do significant figures matter?
They encode measurement precision — reporting 9.81 claims more certainty than 9.8. Calculations shouldn't output more sig figs than the least precise input.