Convert Fractional Inches to Millimeters

"Fractional Inches to Millimeters" Calculator

How to Convert Fractional Inches to Millimeters

Fractional Inches to Millimeters Conversion Formula

To convert fractional inches (SAE) to millimeters, use this precise formula:

millimeters = (numerator ÷ denominator) × 25.4

Step-by-Step Conversion Guide

Take the numerator of your fraction (e.g., 13 in 13/16)
Divide numerator by denominator (13 ÷ 16 = 0.8125)
Multiply result by 25.4 (0.8125 × 25.4 = 20.6375 mm)
Get your precise measurement in millimeters

Common SAE Fractions to Millimeters

Fraction	Millimeters	Common Usage
1/16"	1.5875 mm	Small fasteners
1/8"	3.175 mm	Standard bolts
1/4"	6.35 mm	Wrenches and nuts
3/8"	9.525 mm	Socket wrenches
1/2"	12.7 mm	Large bolts
5/8"	15.875 mm	Industrial fasteners
3/4"	19.05 mm	Pipe fittings
13/16"	20.6375 mm	Special sizes

Practical Applications of SAE to Metric Converter

Automotive: Working with American fasteners and parts
Engineering: Converting tool sizes and specifications
Repair Work: Finding metric equivalents for SAE tools
Manufacturing: Adapting American standards
Woodworking: Precise lumber measurements

Popular Wrench Size Conversion Examples

7/16" wrench size:

7 ÷ 16 = 0.4375
0.4375 × 25.4 = 11.1125 mm
Nearest metric equivalent: 11 mm

Understanding SAE (Society of Automotive Engineers) System

SAE fractions use powers of two in the denominator (2, 4, 8, 16, 32, 64). This allows precise division of an inch into equal parts. Our converter supports all standard SAE sizes and automatically finds the closest fraction for reverse conversions.

Fractional Inches to Millimeters