🔧 Metric → SAE Calculator
Find the closest SAE socket or wrench size for a metric measurement.
Handy in garages and workshops where both metric and SAE tools are used interchangeably.
Metric (mm): 10 mm
Decimal inches: 0.3937 in
Closest SAE size: 13/32" (difference 0.319 mm)
How to Use This Calculator
Measure in metric
Determine the metric size (e.g., bolt head, drill bit) in millimeters or centimeters.
Enter the value
Type the measurement and choose the unit.
Review SAE equivalents
Use the decimal inch value or the suggested SAE fraction to pick the closest tool.
Formula
Inches = Metric length × 0.0393701
Closest SAE fraction = minfraction |decimal inches − fractioninches|
Difference (mm) = |decimal inches − fractioninches| × 25.4
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
Metric and SAE (inch-based) sockets and wrenches don’t always align perfectly. This calculator translates metric measurements into decimal inches and suggests the nearest SAE size so you can pick the best fit when ideal tools aren’t available.
The results include the discrepancy in millimeters, making it clear if the match is acceptably close or if you should look for a precise metric tool.
Frequently Asked Questions
Why only mm and cm?
Those are the typical metric fastener sizes. Convert other units to mm before entering them.
How accurate is the suggestion?
The calculator finds the nearest SAE fraction. Always confirm the fit to avoid rounding issues.
Can I add more fractions?
Yes. Extend the SAE_FRACTIONS array with additional sizes such as 1-1/16".
Does it support reverse conversions?
Use the measurement converter or enter the SAE fraction’s decimal inches manually if needed.