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Significant figures Calculator

Round a value to n significant figures.

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Result
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Rounded Value

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Overview

Significant figures represent the digits in a numerical value that carry meaningful information about its precision and measurement certainty. This convention ensures that data reporting and subsequent calculations accurately reflect the limitations of the original measuring instrument.

Symbols

Variables

x = Original Value, n = Significant Figures, x_{rounded} = Rounded Value

Original Value
Significant Figures
Rounded Value

Apply it well

When To Use

When to use: Significant figures should be used whenever reporting experimental measurements or performing calculations with real-world data. They are necessary to ensure the final result does not claim more precision than the least precise measurement allowed.

Why it matters: In high-stakes fields like medicine, engineering, and chemistry, maintaining the correct number of significant figures prevents errors in dosages and structural tolerances. Misreporting precision can lead to false confidence in data, resulting in mechanical failures or safety risks.

Avoid these traps

Common Mistakes

  • Rounding before finishing calculations.
  • Counting trailing zeros incorrectly.

One free problem

Practice Problem

A laboratory analyst records the mass of a chemical precipitate as 0.0078452 grams. If the analytical balance is only certified to 3 significant figures, what is the correctly rounded mass?

Original Value0.0078452
Significant Figures3

Solve for:

Hint: Identify the first non-zero digit and count three places to the right, then round based on the fourth digit.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Chemistry: The Central Science (14th ed.) by Brown, LeMay, Bursten, Murphy, Woodward, Stoltzfus
  2. Physics for Scientists and Engineers (10th ed.) by Serway and Jewett
  3. Wikipedia: Significant figures
  4. Atkins' Physical Chemistry
  5. Halliday, Resnick, and Walker, Fundamentals of Physics
  6. IUPAC Gold Book: Significant figures
  7. NIST Guide to the International System of Units (SI) (SP 811)
  8. Standard curriculum — A-Level Sciences (Working Scientifically)