Significant Figures Calculator
Count the significant figures of any number and round it to a chosen precision for science and engineering.
Category: Mathematics
About this tool
What Is a significant figure? Significant Figures Calculator. The significant figures calculator tells you how many meaningful digits a number has and rounds it to as many figures as you need. It is built for students, lab reports, and engineering calculations where precision notation matters. A significant figure is any digit that carries real meaning about a number: all non-zero digits, zeros between them, and trailing zeros that follow a decimal point. Leading zeros do not count because they only fix the decimal position. Mixing measurements of different precision without rounding them first produces misleading results. That is why scientific work reports answers with the same number of significant figures as the least precise input. Zeros between non-zero digits count; trailing zeros after the decimal point count; leading zeros never count. How to Use Type any number, such as 0.0045600 or 1200, into the Number field. Leave the second field empty to see the automatic significant-figure count. To round, type a target from 1 to 15 in the Target sig figs field — the rounded value appears immediately. Worked Example Enter 0.0045600. The tool reports 5 significant figures because the digits 4, 5, 6 and the trailing zeros hold information. Requesting 3 significant figures returns 0.00456, while 3 figures of 2.345 give 2.35 (half-up rounding). Common Use Cases lab reports and physi