UNC to Metric / UNF to Metric conversion

Comparison of inch threads and metric threads
Inch thread (UNC) vs. Metric Thread (M3)

 

Conversion data for UNC to metric fasteners for industrial bolts and machine screws. While metric screws and inch screws may appear similar, they possess different thread types and fundamental units. It's important to note that these screw types are not compatible and cannot be swapped interchangeably. The following conversion chart aims to illustrate the inch screws and metric screws that can be effectively compared.

UNC to metric Converstion Chart

 

In the inch screw table for UNC, we provide a clear comparison of the most common sizes. On the left side of the table, you will find the UNC thread, and on the right side, the metric coarse thread (often referred to as standard thread). By juxtaposing them, one can quickly get an idea of which UNC thread is approximately equivalent to which metric thread, providing a rough estimation of the sizes as well.

 

Inch thread table

 

Metric coarse thread

 

UNC

Thread diameter
outside in mm

Metric thread

Size x Pitch

Thread diameter
outside in mm
N 1 - 64 1,854 mm M2 x 0.40 2,00 mm
N 3 - 48 2,515 mm M2.5 x 0.45 2,50 mm
 N 4 - 40 2,845 mm M3 x 0.50 3,00 mm
N 6 - 32 3,505 mm M3.5 x 0.60 3,50 mm
N 8 - 32 4,166 mm M4 x 0.70 4,00 mm
N 10 - 24 4,826 mm M5 x 0.80 5,00 mm
1/4" - 20 6,350 mm M6 x 1.00 6,00 mm
5/16" - 18 7,938 mm M8 x 1.25 8,00 mm
3/8" - 16 9,525 mm M10 x 1.50 10,00 mm
1/2" - 13 12,700 mm M12 x 1.75 12,00 mm
9/16" - 12 14,288 mm M14 x 2.00 14,00 mm
5/8" - 11 15,875 mm M16 - 2.00 16,00 mm
3/4" - 10 19,050 mm M20 x 2.50 20,00 mm
7/8" - 9 22,225 mm M22 x 2.50 22,00 mm
1" - 8 25,400 mm M24 x 3.00 24,00 mm
1 - 1/8" - 7 28,575 mm M27 x 3.00 27,00 mm
1 - 1/4" - 7 31,750 mm M30 x 3.50 30,00 mm
1 - 1/2" - 6 38,100 mm M36 x 4.00 36,00 mm
1 - 3/4" - 5 44,450 mm M42 x 4.50 42,00 mm
2" - 4 1/2 50,800 mm M48 x 5.00 48,00 mm

* All information without guarantee.

 

UNF to metric Converstion Chart

 

In the inch screw table for UNF, we provide a clear comparison of the most common sizes. On the left side of the table, you will find the UNF thread, while on the right side, you will find the metric fine thread. UNF inch screws serve as the equivalent to the European fine thread, offering a side-by-side reference for easy comparison.

 

Inch thread table

 

Metric fine thread

 

UNF

Thread diameter
outside in mm

Metric fine thread

Size x Pitch

Thread diameter
outside in mm
1/4" - 28 6,350 mm M6 x 0.75 6,00 mm
5/16" - 24 7,938 mm M8 x 1.00 8,00 mm
3/8" - 24 9,525 mm M10 x 1.25 10,00 mm
1/2" - 20 12,700 mm M12 x 1.50 12,00 mm
9/16" - 18 14,288 mm M14 x 1.50 14,00 mm
5/8" - 18 15,875 mm M16 x 1.50 16,00 mm
3/4" - 16 19,050 mm M20 x 1.50 20,00 mm
7/8" - 14 22,225 mm M22 x 1.50 22,00 mm
1" - 12 25,400 mm M24 x 2.00 24,00 mm
1 - 1/8" - 12 28,575 mm M27 x 2.00 27,00 mm
1 - 1/4" - 12 31,750 mm M30 x 2.00 30,00 mm
1 - 1/2" - 12 38,100 mm M36 x 2.00 36,00 mm

* All information without guarantee.

 

 

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