Sig Fig Calculator (Significant Figures)
Free significant figures calculator. Count sig figs in any number, round to N significant figures, and perform add, subtract, multiply, and divide with correct sig-fig rounding rules. 100% client-side.
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What is Sig Fig Calculator (Significant Figures)?
The Sig Fig Calculator is a free, browser-based tool that counts the significant figures in any number, rounds values to a chosen number of significant figures, and performs addition, subtraction, multiplication, and division while automatically applying the correct sig-fig rounding rules. It handles leading zeros, captive zeros, trailing zeros after a decimal point, and scientific notation, so you can trust the results for chemistry labs, physics problem sets, and engineering measurements. Everything runs locally in your browser — no sign-up, no downloads, and no data ever leaves your device.
Key Benefits
- Instantly counts significant figures with correct rule application
- Rounds to N significant figures while preserving trailing zeros
- Automatic sig-fig rounding for add, subtract, multiply, and divide
- Supports scientific notation and tricky trailing-zero cases
- 100% client-side, free, and works offline
Common Use Cases
- •Checking the significant figures of a chemistry lab measurement
- •Rounding physics problem-set answers to the correct precision
- •Verifying engineering calculations respect measurement uncertainty
- •Teaching or learning the rules of significant figures
- •Quickly rounding a value to a specific number of sig figs
How to Use the Sig Fig Calculator
- Enter a Number: Type any number (e.g. 0.00450, 2300, or 1.23e4). The tool instantly counts how many significant figures it contains.
- Round to N Figures (Optional): Enter a number in the "Round to" box (e.g. 3) to round the value to that many significant figures while preserving trailing zeros.
- Do Sig-Fig Arithmetic (Optional): Switch to the arithmetic section, enter two numbers, and pick an operation (add, subtract, multiply, or divide). The result is rounded using the correct sig-fig rule automatically.
- Copy the Result: Click Copy next to any result to copy it to your clipboard. Use Reset to clear all fields and start over.
Key Features
- Instantly counts significant figures in any number, including scientific notation
- Rounds values to a chosen number of significant figures while preserving trailing zeros
- Performs add, subtract, multiply, and divide with automatic sig-fig rounding
- Applies the correct rule per operation: fewest decimal places for +/−, fewest sig figs for ×/÷
- Shows the sig-fig count of every operand and explains which rounding rule was used
- 100% client-side and offline-capable — no sign-up, no data uploads