Significant Figures Calculator

Significant figures indicate the precision of a measurement.

Rules for counting sig figs:

1. All non-zero digits are significant: 1234 → 4 sig figs
2. Zeros between non-zero digits are significant: 1002 → 4 sig figs
3. Leading zeros are NOT significant: 0.0045 → 2 sig figs
4. Trailing zeros after decimal ARE significant: 2.300 → 4 sig figs
5. Trailing zeros without decimal are ambiguous: 1200 → 2, 3, or 4 sig figs (use scientific notation to clarify)

Rounding rules:

• If the digit to drop is < 5, round down
• If the digit to drop is > 5, round up
• If the digit to drop is exactly 5, round to the nearest even number (banker"s rounding)

Examples:

• 0.00340 → 3 sig figs (3, 4, and trailing 0)
• 100.0 → 4 sig figs (trailing zero after decimal)
• 2.997 × 10⁸ → 4 sig figs