Significant Figures and Rounding Checker CHEM TOOLS
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Significant-figures and rounding checker with LOD/LOQ reporting

Turn measured values, instrument resolution, standard deviation, and rounding rules into report-ready notation.

If an internal standard, customer rule, or regulation applies, follow it before this suggestion.

Updates the recommended notation as you type Compares LOD and LOQ reporting candidates side by side Share the result and its short reason in one click Reuse presets and recent calculations

Quick examples

Review the main cases before you start

Round from resolution

Input Value 1.2345, resolution 0.01, round half up
Output 1.23

Below LOD

Input Value 0.034, LOD 0.05, style below LOD
Output <0.05

Round from standard deviation

Input Value 12.3, σ 0.56, uncertainty 2 digits
Output 12.30

How to use it

  1. Enter the measured value and add a unit if it should appear in the final text.
  2. Enter the instrument resolution or standard deviation, then choose a rounding rule.
  3. If LOD or LOQ applies, enter the threshold and select the reporting style to compare.
  4. Copy the recommended notation, then share the short reason or full analysis report when needed.

Glossary

Significant figures

Digits that are justified by the precision of the measurement.

Measurement resolution

The smallest readable increment on the instrument or display; it can serve as a reporting-precision basis.

Standard deviation (σ)

The spread of repeated measurements. Round σ to 1 or 2 digits, then align the reported value to the same place.

LOD

Limit of detection. Below this threshold, the calculator prioritizes non-quantitative reporting candidates.

LOQ

Limit of quantification. Values below this threshold may be detectable but unsuitable as reported quantitative results.

Decision logic

  • Resolution basis = the resolution value you enter
  • Sigma basis = the last significant place after rounding σ to 1 or 2 digits
  • Recommended increment = selected from resolution, sigma, or the coarser requirement
  • Rounded value = the input rounded to the recommended increment with the selected rule
  • If value < LOD, show below-LOD candidates; if value < LOQ, show below-LOQ candidates.

Frequently asked questions

Can I save settings for our reporting standard?

Yes. Save rule presets in the browser, then export or import them as JSON.

How does the tool report values below LOD?

It offers common candidates such as <LOD, ND, and below-LOQ wording. Use the form required by your standard.

Can I change the number format?

Yes. Follow the browser default, switch to Japanese or European formatting, or remove digit grouping.

What if I enter both resolution and standard deviation?

Choose resolution, standard deviation, or the coarser requirement as the reporting basis. The default is the coarser requirement.

Does the tool send data to a server?

No. Calculations, presets, and recent history remain in your browser.

Important notes

  • This tool suggests notation based on common rounding and reporting practices.
  • If an internal standard, customer requirement, regulation, test method, or SOP says otherwise, follow it first.
  • LOD and LOQ practices vary by field and standard, so the tool presents candidates rather than one claimed correct answer.