What relationship is used?

The common ASTM relation N = 2^(G - 1) for grains per square inch at 100x.

Is this a full ASTM E112 workflow?

No. It is a converter. Use the ASTM E112 analyzer for measurement workflow support.

Can I convert in the other direction?

This P2 version focuses on G to area metrics. Reverse conversion can be added later.

ToolsConductScience tool

ASTM E112Free in-browser calculator

ASTM Grain Size Number Converter.

Convert grain size number into area-density and approximate mean-grain-area values. For materials research, education, and protocol documentation only. Not a certified inspection, compliance, asset-integrity, or final acceptance tool.

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Validated2026-05-24

CitableMethods and citation included

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Try it out

Load example grain number data to see the full workflow

Grain Number inputs

ASTM grain size number G

Results

Grains at 100x

128 per in2

Grains per mm2

0.1984

Mean grain area

5040312.5 um2

grains/mm2

0.198

Review notes

Use calibrated metallography methods when deriving G from images or intercept counts.

Methods note

Uses N = 2^(G - 1), where N is grains per square inch at 100x.

Scope and limitations

For materials research, education, and protocol documentation only. Not a certified inspection, compliance, asset-integrity, or final acceptance tool.

Results are deterministic calculations from the values entered here. Review units, assumptions, and measurement quality before using outputs in reports or protocols.

Method

Uses the tool-specific formulas and assumptions shown in the calculator output.

Validated

Last validated 2026-05-24. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

How to cite

How to Cite

ASTM Grain Size Number Converter (1.2.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/grain-size-number-converter

For materials research, education, and protocol documentation only. Not a certified inspection, compliance, asset-integrity, or final acceptance tool.

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