CALCULATE WITH CONFIDENCE

Number Fundamentals & Precision

Round to Significant Figures Calculator

Apply half-even rounding to 1–100 significant figures.

Exact arithmetic

Round to a significant-digit count

Half even · 1–100
  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
Try an example

Rounded value

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Enter valid values to see the result.

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Understand the subject

How do significant figures control rounding?

Significant-figure rounding begins at the first meaningful digit, regardless of where the decimal marker appears.

Use it to report a number at a consistent meaningful precision across very large and very small values.

The key rule

What stays true

See the idea

Visual explanation

Example

Apply it

The first three digits are 1, 2, and 3; the next digit 4 does not raise them.

Leading zeros do not count as significant; written trailing zeros may require explicit notation.

Quick guide

How to use this calculator

  1. Enter a nonzero or zero finite decimal.
  2. Choose the significant-figure count.
  3. Use the explicit notation to see retained trailing zeros, including zero's stated precision.

Calculation method

Precision follows the first nonzero digit

The first nonzero digit establishes the leading power of ten. The calculator keeps the requested count from there and applies half-even at the next digit.

Worked example

Three significant figures

The first three significant digits of 12,345 are 1, 2, and 3; the following 4 does not raise them.

12,345 → 1.23 × 10⁴

Supported inputs

Precision and limits

Exact decimal input

Finite decimals use integer-scaled arithmetic, with no binary floating-point conversion.

Input boundary

Unless stated otherwise, use at most 200 digits total and 100 digits after the decimal marker.