Metric-to-Imperial Thread Conversion Tables.
Precision is a cornerstone in engineering, where the exact dimensions of components like screws can significantly impact the outcome.
Navigating between metric thread and imperial thread measurements often presents challenges, especially when selecting high-precision screws for specific applications.
Our imperial-to-metric conversion chart provides engineers with an essential resource for accurate metric-to-imperial thread conversions, ensuring you find the perfect match for your needs, or finally figure out exactly what that odd screw actually is.
Interchanging metric and imperial threaded fasteners involves more than just matching sizes; it requires careful consideration of differences in major diameters and thread pitches. By utilising our metric-to-imperial thread conversion charts, you can confidently bridge the gap between these measurement systems and maintain the integrity of your assemblies.
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Metric-to-Imperial Major Diameters
The major diameter is the external diameter of the screw thread, and matching this dimension is vital for component compatibility. Our major diameter conversion chart offers precise equivalents between metric and imperial measurements, simplifying the process of finding suitable fasteners.
| Imperial Thread Size | Major Diameter (Inch) | Major Diameter (MM) | Metric Thread Size |
|---|---|---|---|
| - | 0.0394 | 1.0000 | M1 |
| - | 0.0433 | 1.1000 | M1.1 |
| - | 0.0472 | 1.2000 | M1.2 |
| - | 0.0551 | 1.4000 | M1.4 |
| #0 | 0.0600 | 1.5240 | - |
| - | 0.0630 | 1.6000 | M1.6 |
| - | 0.0709 | 1.8000 | M1.8 |
| #1 | 0.0730 | 1.8542 | - |
| - | 0.0787 | 2.0000 | M2 |
| #2 | 0.0860 | 2.1844 | - |
| - | 0.0866 | 2.2000 | M2.2 |
| - | 0.0984 | 2.5000 | M2.5 |
| #3 | 0.0990 | 2.5146 | - |
| #4 | 0.1120 | 2.8448 | - |
| - | 0.1181 | 3.0000 | M3 |
| #5 | 0.1250 | 3.1750 | - |
| - | 0.1378 | 3.5000 | M3.5 |
| #6 | 0.1380 | 3.5052 | - |
| - | 0.1575 | 4.0000 | M4 |
| #8 | 0.1640 | 4.1656 | - |
| - | 0.1772 | 4.5000 | M4.5 |
| #10 | 0.1900 | 4.8260 | - |
| - | 0.1969 | 5.0000 | M5 |
| #12 | 0.2160 | 5.4864 | - |
| - | 0.2362 | 6.0000 | M6 |
| 1/4" | 0.2500 | 6.3500 | - |
| - | 0.2756 | 7.0000 | M7 |
| 5/16" | 0.3125 | 7.9502 | - |
| - | 0.3150 | 8.0000 | M8 |
| - | 0.3543 | 9.0000 | M9 |
| 3/8" | 0.3750 | 9.5250 | - |
| - | 0.3937 | 10.0000 | M10 |
| - | 0.4331 | 11.0000 | M11 |
| 7/16" | 0.4375 | 11.1252 | - |
| - | 0.4724 | 12.0000 | M12 |
| 1/2" | 0.5000 | 12.7000 | - |
| - | 0.5512 | 14.0000 | M14 |
| 9/16" | 0.5625 | 14.3002 | - |
| 5/8" | 0.6250 | 15.8750 | - |
| - | 0.6299 | 16.0000 | M16 |
| - | 0.7087 | 18.0000 | M18 |
| 3/4" | 0.7500 | 19.0500 | - |
| - | 0.7874 | 20.0000 | M20 |
| - | 0.8661 | 22.0000 | M22 |
| 7/8" | 0.8750 | 22.2250 | - |
| - | 0.9449 | 24.0000 | M24 |
| 1" | 1.0000 | 25.4000 | - |
| - | 1.0630 | 27.0000 | M27 |
| - | 1.1811 | 30.0000 | M30 |
Metric-to-Imperial Thread Pitch
Thread pitch refers to the distance between threads on a screw, influencing how tightly components are fastened. Coarse pitches have fewer threads per unit length, allowing for quicker assembly, while fine pitches offer more threads for a secure fit. Our thread pitch conversion chart compares metric pitches with imperial pitches, enabling you to select fasteners with similar threading and avoid issues related to mismatched pitches.
| Imperial Thread Size |
TPI (Threads Per Inch) |
Thread Pitch (Inch) | Thread Pitch (MM) | Metric Thread Size |
|---|---|---|---|---|
| - | - | 0.0098 | 0.2500 | M1 M1.1 M1.2 |
| - | - | 0.0118 | 0.3000 | M1.4 |
| #0 (UNF) | 80 | 0.0125 | 0.3175 | - |
| - | - | 0.0138 | 0.3500 | M1.6 M1.8 |
| #1 (UNF) | 72 | 0.0139 | 0.3528 | - |
| #1 (UNC) #2 (UNF) |
64 | 0.0156 | 0.3969 | - |
| - | - | 0.0157 | 0.4000 | M2 |
| - | - | 0.0177 | 0.4500 | M2.2 M2.5 |
| #2 (UNC) #3 (UNF) |
56 | 0.0179 | 0.4536 | - |
| - | - | 0.0197 | 0.5000 | M3 |
| #3 (UNC) #4 (UNF) |
48 | 0.0208 | 0.5292 | - |
| #5 (UNF) | 44 | 0.0227 | 0.5773 | - |
| - | - | 0.0236 | 0.6000 | M3.5 |
| #4 (UNC) #5 (UNC) #6 (UNF) |
40 | 0.0250 | 0.6350 | - |
| - | - | 0.0276 | 0.7000 | M4 |
| - | - | 0.0295 | 0.7500 | M4.5 |
| #8 (UNF) | 36 | 0.0278 | 0.7056 | - |
| #6 (UNC) #8 (UNC) #10 (UNF) #12 (UNEF) 1/4" (UNEF) 5/16" (UNEF) 3/8" (UNEF) |
32 | 0.0313 | 0.7938 | - |
| - | - | 0.0315 | 0.8000 | M5 |
| #12 (UNF) 1/4" (UNF) 7/16" (UNEF) 1/2" (UNEF) |
28 | 0.0357 | 0.9071 | - |
| - | - | 0.0394 | 1.0000 | M6 M7 |
| #10 (UNC) #12 (UNC) 5/16" (UNF) 3/8" (UNF) 9/16" (UNEF) 5/8" (UNEF) |
24 | 0.0417 | 1.0583 | - |
| - | - | 0.0492 | 1.2500 | M8 M9 |
| 1/4" (UNC) 7/16" (UNF) 1/2" (UNF) 3/4" (UNEF) 7/8" (UNEF) 1" (UNEF) |
20 | 0.0500 | 1.2700 | - |
| 5/16" (UNC) 9/16" (UNF) 5/8" (UNF) |
18 | 0.0556 | 1.4111 | - |
| - | - | 0.0591 | 1.5000 | M10 M11 |
| 3/8" (UNC) 3/4" (UNF) |
16 | 0.0625 | 1.5875 | - |
| - | - | 0.0689 | 1.7500 | M12 |
| 7/16" (UNC) 7/8" (UNF) |
14 | 0.0714 | 1.8143 | - |
| 1/2" (UNC) | 13 | 0.0769 | 1.9538 | - |
| - | - | 0.0787 | 2.0000 | M16 |
| 9/16" (UNC) 1" (UNF) |
12 | 0.0833 | 2.1167 | - |
| 5/8" (UNC) | 11 | 0.0909 | 2.3091 | - |
| - | - | 0.0984 | 2.5000 | M18 M20 M22 |
| 3/4" (UNC) | 10 | 0.1000 | 2.5400 | - |
| 7/8" (UNC) | 9 | 0.1111 | 2.8222 | - |
| - | - | 0.1181 | 3.0000 | M24 M27 |
| 1" (UNC) | 8 | 0.1250 | 3.1750 | - |
| - | - | 0.1378 | 3.5000 | M30 M33 |
Common Metric & Imperial Screw Lengths
Accurate length conversions between metric and imperial units are often necessary to ensure components fit as intended. Our conversion table for common lengths provides straightforward equivalents, allowing you to translate measurements seamlessly. By referring to this chart, you can select screws and other components that meet your exact specifications, enhancing the precision and reliability of your projects.
| Imperial Fractional Length | Length (Inch) | Length (MM) | Metric Length |
|---|---|---|---|
| - | 0.0787 | 2.0000 | 2mm |
| - | 0.1181 | 3.0000 | 3mm |
| 1/8" | 0.1250 | 3.1750 | - |
| 5/32" | 0.1563 | 3.9700 | - |
| - | 0.1575 | 4.0000 | 4mm |
| 3/16" | 0.1875 | 4.7625 | - |
| - | 0.1969 | 5.0000 | 5mm |
| 7/32" | 0.2188 | 5.5575 | - |
| - | 0.2362 | 6.0000 | 6mm |
| 1/4" | 0.2500 | 6.3500 | - |
| - | 0.2559 | 6.5000 | 6.5mm |
| - | 0.2756 | 7.0000 | 7mm |
| 9/32" | 0.2813 | 7.1450 | - |
| 5/16" | 0.3125 | 7.9375 | |
| - | 0.3150 | 8.0000 | 8mm |
| 11/32" | 0.3438 | 8.7325 | - |
| 3/8" | 0.3750 | 9.5250 | - |
| - | 0.3937 | 10.0000 | 10mm |
| - | 0.3937 | 10.0000 | 10mm |
| 7/16" | 0.4375 | 11.1125 | - |
| - | 0.4724 | 12.0000 | 12mm |
| 1/2" | 0.5000 | 12.7000 | - |
| - | 0.5512 | 14.0000 | 14mm |
| 9/16" | 0.5625 | 14.2875 | - |
| - | 0.5906 | 15.0000 | 15mm |
| 5/8" | 0.6250 | 15.8750 | - |
| - | 0.6299 | 16.0000 | 16mm |
| 11/16" | 0.6875 | 17.4625 | - |
| - | 0.7087 | 18.0000 | 18mm |
| 3/4" | 0.7500 | 19.0500 | - |
| - | 0.7874 | 20.0000 | 20mm |
| 13/16" | 0.8125 | 20.6375 | - |
| - | 0.8661 | 22.0000 | 22mm |
| 7/8" | 0.8750 | 22.2250 | - |
| 15/16" | 0.9375 | 23.8125 | - |
| - | 0.9843 | 25.0000 | 25mm |
| 1" | 1.0000 | 25.4000 | - |
| - | 1.1811 | 30.0000 | 30mm |
| 1 1/4" | 1.2500 | 31.7500 | - |
| - | 1.3780 | 35.0000 | 35mm |
| 1 1/2" | 1.5000 | 38.1000 | - |
| - | 1.5748 | 40.0000 | 40mm |
| 1 3/4" | 1.7500 | 44.4500 | - |
| - | 1.7717 | 45.0000 | 45mm |
| - | 1.9685 | 50.0000 | 50mm |
| 2" | 2.0000 | 50.8000 | - |
| - | 2.1654 | 55.0000 | 55mm |
| 2 1/4" | 2.2500 | 57.1500 | - |
| - | 2.3622 | 60.0000 | 60mm |
| 2 1/2" | 2.5000 | 63.5000 | - |
| - | 2.5591 | 65.0000 | 65mm |
| 2 3/4" | 2.7500 | 69.8500 | - |
| - | 2.7559 | 70.0000 | 70mm |
| - | 2.8740 | 73.0000 | 73mm |
| 3" | 3.0000 | 76.2000 | - |
| - | 3.1496 | 80.0000 | 80mm |
| - | 3.3465 | 85.0000 | 85mm |
| 3 1/2" | 3.5000 | 88.9000 | - |
| - | 3.5433 | 90.0000 | 90mm |
| - | 3.7402 | 95.0000 | 95mm |
| - | 3.9370 | 100.0000 | 100mm |
| 4" | 4.0000 | 101.6000 | - |
| - | 4.3307 | 110.0000 | 110mm |
| 4 1/2" | 4.5000 | 114.3000 | - |
| - | 4.5276 | 115.0000 | 115mm |
| - | 4.7244 | 120.0000 | 120mm |
| - | 4.9213 | 125.0000 | 125mm |
| 5" | 5.0000 | 127.0000 | - |
| - | 5.1181 | 130.0000 | 130mm |
| - | 5.3150 | 135.0000 | 135mm |
| - | 5.9055 | 150.0000 | 150mm |
| 6" | 6.0000 | 152.4000 | - |
| - | 6.2992 | 160.0000 | 160mm |
| - | 6.6929 | 170.0000 | 170mm |
| - | 7.0866 | 180.0000 | 180mm |
| - | 7.4803 | 190.0000 | 190mm |
| - | 7.8740 | 200.0000 | 200mm |
| 8" | 8.0000 | 203.2000 | - |