Bolt Grade Strength Decoder
Decode 8.8 / 10.9 / 12.9 markings into tensile and yield strength.
The marking IS the datasheet: 8.8 = 800/640, 10.9 = 1000/900, 12.9 = 1200/1080 MPa. Unmarked bolts are grade 'unknown' — treat as 4.6 and sleep at night.
Formula
Bolt Grade Strength Decoder is a free bolt grade meaning for design engineers, metallurgists and QA inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Bolt Grade Strength Decoder
Decode 8.8 / 10.9 / 12.9 markings into tensile and yield strength. The calculation implements First digit ×100 = UTS (MPa); ×second digit/10 = yield (ISO 898-1 designation system). The marking IS the datasheet: 8.8 = 800/640, 10.9 = 1000/900, 12.9 = 1200/1080 MPa. Unmarked bolts are grade 'unknown' — treat as 4.6 and sleep at night.
How to use Bolt Grade Strength Decoder
- 1Enter Property class (e.g. 8.8).
- 2Read Tensile strength, Yield strength instantly — no submit button needed.
- 3Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Bolt Grade Strength Decoder?
- ✓Implements the standard formula — First digit ×100 = UTS (MPa); ×second digit/10 = yield
- ✓Reference cited on-page: ISO 898-1 designation system
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Bolt Grade Strength Decoder use?+
It computes First digit ×100 = UTS (MPa); ×second digit/10 = yield, per ISO 898-1 designation system. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
The marking IS the datasheet: 8.8 = 800/640, 10.9 = 1000/900, 12.9 = 1200/1080 MPa. Unmarked bolts are grade 'unknown' — treat as 4.6 and sleep at night.
Where do the material property defaults come from?+
Defaults are standard handbook values (ASM, manufacturer datasheets, the cited standard). Always substitute certified values from your material's test certificate for critical work.
Is the Bolt Grade Strength Decoder free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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