Are trailing zeros without a decimal point significant?

No. In a number like 1200 (no decimal point), the trailing zeros are ambiguous and are treated as non-significant by this tool. Use scientific notation or a decimal point (1200.) to make them significant.

Are leading zeros significant?

No. Zeros before the first non-zero digit (like the zeros in 0.0042) are placeholders and never count as significant figures.

Are zeros between non-zero digits significant?

Yes, always. A zero sandwiched between two non-zero digits (like the zero in 1.05 or 307) is significant.

What about trailing zeros after a decimal point?

Yes, they are significant. If a number is written as 3.500, all four digits count because the written decimal point signals that precision was intentional.

How does this handle scientific notation like 1.23e4?

The tool reads only the coefficient (1.23) for sig fig counting in scientific notation, giving 3 significant figures.

Sig Fig Counter

Type any number to instantly count its significant figures, with each digit highlighted to show whether it counts.

Enter a Number

Try an example

Result

Type a number on the left to see its sig figs.

Summary

This tool counts the significant figures in any number you type, applying the standard rules for zeros and decimal points. Each digit in your number is highlighted green (significant) or gray (not significant) so you can see exactly which ones count. Useful for chemistry, physics, and math courses where precision matters.

How it works

Type or paste a number into the input field.
The tool parses the number and applies standard significant figure rules.
Each digit is color-coded: green for significant, gray for non-significant.
The total sig fig count and the applied rule are displayed below the number.
Edit the number at any time — the count updates instantly.

Use cases

Verify sig fig counts before submitting chemistry or physics homework.
Check whether trailing zeros after a decimal point are significant.
Understand why leading zeros in decimals like 0.0042 do not count.
Confirm sig figs in scientific measurements before rounding.
Quickly count sig figs on multiple numbers during a lab report.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu