Sig Fig Calculator
Enter any number to count its significant figures and optionally round to a specific number of sig figs.
Significant Figures — Rules
Rules for counting sig figs
- All non-zero digits are significant: 1234 → 4 sig figs
- Zeros between non-zeros are significant: 1002 → 4 sig figs
- Leading zeros are NOT significant: 0.0045 → 2 sig figs
- Trailing zeros after a decimal ARE significant: 1.200 → 4 sig figs
- Trailing zeros without a decimal are ambiguous: 1200 → 2–4 sig figs
Examples
| Number | Sig Figs | Reason |
|---|---|---|
| 0.00420 | 3 | 4, 2, 0 (trailing after decimal) |
| 1030.0 | 5 | all digits |
| 5.00 × 10⁵ | 3 | 5, 0, 0 |
| 1200 | 2 | trailing zeros without decimal |
