Industrial Data Depository

M3 ≈ #4-40
M5 ≈ 10-24
M6 ≈ 1/4-20
Bolt Strength Grade Chart: ISO vs SAEHex Key Size Chart: Metric to ImperialM10 vs 3/8-16 UNC Screw Size ChartM12 vs 1/2-13 UNC Screw Size ComparisonM16 vs 5/8-11 UNC Screw Size ChartM20 vs 3/4-10 UNC Screw Size ChartM3 vs #4-40 UNC Screw Size ChartM4 vs #8-32 UNC Screw Size ComparisonM5 vs 10-24 UNC Screw SizeM6 vs 1/4-20 UNC Screw Size ChartM8 vs 5/16-18 UNC Screw Size ComparisonMetric vs UNC Thread Pitch Comparison