Free online significant figures calculator for students, teachers, and scientists. Solve expressions, count sig figs, apply rounding rules, and handle log/ln operations with precision.
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Get instant answers to common significant figures questions
All non-zero digits (2, 5) and trailing zero after decimal count
Leading zeros don't count; only 6 and trailing 0 count
Leading zeros don't count; 2, 5, and trailing 0 count
Trailing zeros without decimal are ambiguous (only 1 counts)
Decimal point makes trailing zeros significant (all count)
All digits are non-zero or between non-zero digits
Professional sig figs calculator with instant answers, step-by-step explanations, and comprehensive rounding rules for chemistry, physics, and scientific calculations.
Follow these simple rules to count sig figs accurately every time
All non-zero digits are ALWAYS significant. Example: 123 has 3 sig figs.
Zeros between non-zero digits are significant. Example: 1002 has 4 sig figs.
Trailing zeros after decimal are significant. Example: 1.20 has 3 sig figs.
Leading zeros are NEVER significant (0.0025 = 2 sig figs)
Trailing zeros without decimal are ambiguous (100 = 1 sig fig)
Counted items have infinite sig figs (12 eggs = ∞ sig figs)
1.20 × 10³ has 3 sig figs (count only the coefficient)
Get answers to common sig figs questions from students and scientists
Answer: 3 significant figures. The leading zero doesn't count (it's just a placeholder). The digits 2, 5, and the trailing 0 after the decimal all count as significant figures. The trailing zero is significant because it comes after the decimal point and after non-zero digits, indicating measurement precision to the third decimal place.
Answer: 2 significant figures. The two leading zeros are not significant (they're placeholders). Only the 6 and the trailing 0 count. The trailing zero is significant because it follows the decimal point and indicates measurement precision.
Answer: 3 significant figures. The three leading zeros don't count. The digits that count are 2, 5, and the trailing 0. The trailing zero is significant because it comes after the decimal point, showing the measurement was precise to that digit.
Significant figures (sig figs) are the meaningful digits in a number that indicate measurement precision. They matter in science because they show how accurate your measurements are. For example, 1.5 g and 1.50 g convey different precision - the latter was measured more precisely to the hundredths place. Using correct sig figs prevents reporting false precision in calculations.
No, leading zeros never count. They're only placeholders that locate the decimal point. For example, in 0.0025, the three leading zeros don't count - only the 2 and 5 are significant, giving 2 sig figs total. This rule applies regardless of how many leading zeros there are.
It depends on the decimal point. Trailing zeros AFTER a decimal point are significant (1.20 = 3 sig figs). Trailing zeros WITHOUT a decimal point are ambiguous (100 could be 1, 2, or 3 sig figs). To make trailing zeros significant without a decimal, use scientific notation (1.00 × 10² clearly shows 3 sig figs).
Count 3 significant figures from the left, then round at the next digit. Examples: 12.346 → 12.3 (round down), 0.004567 → 0.00457 (round up), 1,234,567 → 1,230,000 or 1.23 × 10⁶. Use our calculator above to round any number to 3 sig figs automatically with step-by-step explanations.
Yes! Our calculator supports complex mathematical expressions including addition, subtraction, multiplication, division, logarithms (log, ln), and scientific notation. It automatically maintains proper significant figure precision throughout multi-step calculations, following standard rounding rules used in chemistry and physics.
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