Thread Pitch Conversion
APPROXIMATE PITCH/TPI – METRIC TO INCH CONVERSION CHART
Pitch (mm) | Calculated Pitch (inches) | Threads per inch | Pitch (inches) | Calculated Inch Pitch (mm) |
---|---|---|---|---|
0.20 | 0.007874 | 80 | 0.012500 | 0.32 |
0.25 | 0.009843 | 72 | 0.013899 | 0.35 |
0.30 | 0.011811 | 64 | 0.015625 | 0.40 |
0.35 | 0.013780 | 56 | 0.017857 | 0.45 |
0.40 | 0.015748 | 48 | 0.020833 | 0.53 |
0.45 | 0.017717 | 44 | 0.022727 | 0.58 |
0.50 | 0.019685 | 40 | 0.025000 | 0.64 |
0.55 | 0.021654 | 36 | 0.027778 | 0.71 |
0.60 | 0.023622 | 32 | 0.031250 | 0.79 |
0.65 | 0.025591 | 28 | 0.035714 | 0.91 |
0.70 | 0.027559 | 27 | 0.037037 | 0.94 |
0.75 | 0.029528 | 24 | 0.041667 | 1.06 |
0.80 | 0.031496 | 20 | 0.050000 | 1.27 |
1.00 | 0.039370 | 18 | 0.055556 | 1.41 |
1.25 | 0.049213 | 16 | 0.062500 | 1.59 |
1.50 | 0.059055 | 14 | 0.071429 | 1.81 |
1.75 | 0.068898 | 13 | 0.076923 | 1.95 |
2.00 | 0.078740 | 12 | 0.083333 | 2.12 |
2.50 | 0.098425 | 11.5 | 0.086957 | 2.21 |
3.00 | 0.118110 | 11 | 0.090909 | 2.31 |
3.50 | 0.137795 | 10 | 0.100000 | 2.54 |
4.00 | 0.157480 | 9 | 0.111111 | 2.82 |
4.50 | 0.177165 | 8 | 0.125000 | 3.18 |
5.00 | 0.196850 | 7 | 0.142857 | 3.63 |
5.50 | 0.216535 | 6 | 0.166667 | 4.23 |
6.00 | 0.236220 | 5 | 0.200000 | 5.08 |
8.00 | 0.314960 | 4.5 | 0.222222 | 5.64 |
4 | 0.250000 | 6.35 |
Notes:
Column 1 is the Metric Pitch in “mm”
Column 2 is the approximate conversion of Column 1 to inches
Column 3 is the Base “Inch” Threads per Inch
Column 4 is the Calculated Pitch for the TPI in Column 3
Column 5 is the approximate conversion of the Inch TPI to “mm” Pitch
Columns 2 and 3 are not connected