Significant Figures & Units Tool

Learn How it works

Which digits count?

1. All nonzero digits count: 245 has 3.
2. Zeros between nonzero digits count: 1005 has 4.
3. Leading zeros never count: 0.0042 has 2.
4. Trailing zeros count only if there's a decimal point: 2.50 has 3, 2500 has 2 (but 2500. has 4).

In calculations

• × and ÷: the answer has as many sig figs as the measurement with the fewest sig figs. 2.5 × 3.42 = 8.55 → 8.6.
• + and −: the answer has as many decimal places as the measurement with the fewest decimal places. 12.11 + 0.3 = 12.41 → 12.4.

Scientific notation

Write a number as a × 10ⁿ with 1 ≤ a < 10. 0.00052 = 5.2 × 10⁻⁴. 340,000 = 3.4 × 10⁵.

Try it Sig fig counter

Practice Check yourself

Answer, then tap Check. You get an explanation either way.

1. How many sig figs in 0.0340?Check

2. How many sig figs in 1200?Check

3. How many sig figs in 50.07?Check

4. Round 3.14159 to 3 sig figs.Check

5. 2.0 × 3.456 = ? (correct sig figs)Check

6. Write 0.00052 in scientific notation.

   5.2 × 10⁴ 5.2 × 10⁻⁴ 52 × 10⁻⁵
   Check