Convert 3/8 Inches to MM - Accurate Calculator
Convert 3/8" to millimeters with high precision
Results at Different Precisions
3/8 inch = 9.525 mm exactly.
Exact result
Exact conversion: 3/8 × 25.4 = 9.525 mm.
Approximation
Common approximation: about 9.5 mm for quick ruler checks and rough layout work.
Fit caveat
Do not replace 3/8 inch with 10 mm when tolerance matters. 10 mm is 0.475 mm larger than 3/8 inch.
Drill bits and bolts
3/8 inch is common in drill bit references, bolts, and clearance notes. Check manufacturer tolerance before substituting a metric size.
Dowels and woodworking spacing
For dowels, cabinet hardware, and shop layout, 9.525 mm is the exact conversion and 9.5 mm is the closest simple decimal note.
Nearby fractions help when reading a tape measure: 5/16 inch is 7.9375 mm, 1/4 inch is 6.35 mm, and 1/2 inch is 12.7 mm.
🔧 DIY & Hardware
For hardware and DIY projects, 3/8" equals 9.52 mm, which is essential when working with metric tools or international specifications.
⚙️ Engineering & Manufacturing
In engineering contexts, 3/8" converts to 9.525000 mm with high precision for accurate technical specifications.
Frequently Asked Questions
How many mm is 3/8 inch?
3/8 inch is 9.525 mm exactly.
Is 3/8 inch the same as 10 mm?
No. 3/8 inch is 9.525 mm, while 10 mm is 0.475 mm larger. Use 10 mm only as a rough nearby metric size.
What is the common approximation for 3/8 inch in mm?
The common quick approximation is 9.5 mm. Use 9.525 mm for exact conversion.
What is 3/8 inch used for?
It is often used for drill bits, bolts, dowels, cabinet hardware, and woodworking layout measurements.
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