Convert 5/16 Inches to MM - Accurate Calculator
Convert 5/16" to millimeters with high precision
Results at Different Precisions
5/16 inch to mm answer
5/16 inch = 7.9375 mm exactly.
Exact conversion: 5/16 × 25.4 = 7.9375 mm.
Exact formula
Why 25.4 is exact
5/16 inch is 0.3125 inch. Multiply by the exact conversion factor: 0.3125 × 25.4 = 7.9375 mm.
Common approximation and closest metric size
Use 7.94 mm as a practical rounded decimal. 8 mm is very close, but it is 0.0625 mm larger and should only be used as a rough nearby metric comparison.
Do not assume M8 or 8 mm hardware is an automatic substitute. 8 mm is 0.0625 mm larger than 5/16 inch.
Where this size is used
Bolts and drill bits
5/16 inch is common in bolt, clearance, and drill bit references. Use 7.9375 mm for exact conversion before choosing a metric substitute.
Cabinet and shop hardware
For cabinet hardware, jigs, and shop notes, 7.94 mm is a useful short decimal while preserving the exact 5/16 inch meaning.
Nearby fraction conversions
Nearby fractions: 1/4 inch is 6.35 mm, 3/8 inch is 9.525 mm, and 1/2 inch is 12.7 mm.
🔧 DIY & Hardware
For hardware and DIY projects, 5/16" equals 7.94 mm, which is essential when working with metric tools or international specifications.
⚙️ Engineering & Manufacturing
In engineering contexts, 5/16" converts to 7.937500 mm with high precision for accurate technical specifications.
Need to Convert Different Values?
Use our interactive converter tool to convert any value between inches and millimeters with real-time results.
Go to Interactive ConverterQuick Conversion Links
Explore common inch and millimeter values with dedicated pages.
Related MM to Inches Conversion Tools
Editorial conversion notes
How to use this conversion accurately
Formula
5/16 = 0.3125; 0.3125 × 25.4 = 7.9375 mm exactly.
Rounding, tolerance, and substitution
5/16 inch = 7.9375 mm exactly. 7.94 mm is a practical rounded display. 8 mm is 0.0625 mm larger; M8 is not an automatic substitute because thread pitch and tolerance also matter.
Practical use cases
- Compare bolt and drill-bit diameters before choosing a clearance size.
- Convert cabinet, jig, and shop-hardware dimensions from imperial plans.
Comparisons and examples
- 1/4 inch = 6.35 mm; 3/8 inch = 9.525 mm; 1/2 inch = 12.7 mm.
- Compare diameter, pitch, thread form, length, head, and fit before replacing a 5/16-inch fastener with M8.
Editorial value
Go beyond diameter substitution by explaining the thread and tolerance checks that change the purchase decision.
Route-specific questions
Is 5/16 inch the same as 8 mm?
No. 8 mm is 0.0625 mm larger than 5/16 inch.
Can M8 replace a 5/16-inch bolt?
Not automatically. Check diameter, thread pitch, thread form, tolerance, length, and the mating part.