Velocity (fps) to Flow (gpm) Conversion Table
For Schedule 40, 80 & 10 Pipe

Schedule 40
Velocity (fps)
Nominal
Size
Actual
I.D.
0.5
1
2
3
4
5
6
8
10
15
20
1/8"
 0.269
0.09
0.18
0.35
0.53
0.71
0.89
1.06
1.42
1.77
2.66
3.55
1/4"
 0.364
0.16
0.32
0.65
0.97
1.30
1.62
1.95
2.60
3.25
4.87
6.49
3/8"
 0.493
0.30
0.60
1.19
1.79
2.38
2.98
3.57
4.76
5.95
8.93
11.91
1/2"
 0.622
0.47
0.95
1.90
2.84
3.79
4.74
5.69
7.58
9.48
14.22
18.96
3/4"
 0.824
0.83
1.66
3.33
4.99
6.65
8.32
9.98
13.31
16.63
24.95
33.27
1"
 1.049
1.3
2.7
5.39
8.09
10.78
13.48
16.18
21.57
26.96
40.44
53.92
1.5"
 1.610
3.2
6.4
12.70
19.05
25.40
31.75
38.10
50.81
63.51
95.26
127.01
2.0"
 2.067
5.2
10.5
20.94
31.40
41.87
52.34
62.81
83.74
104.68
157.01
209.35
2.5"
 2.469
7.5
14.9
29.87
44.81
59.74
74.68
89.61
119.48
149.35
224.03
298.70
3.0"
 3.068
11.5
23.1
46.12
69.18
92.24
115.30
138.37
184.49
230.61
345.91
461.22
4.0"
 4.026
19.9
39.7
79.42
119.13
158.85
198.56
238.27
317.69
397.11
595.67
794.23
5.0"
 5.047
31.2
62.4
124.81
187.22
249.63
312.03
374.44
499.26
624.07
936.10
1248.14
6.0"
 6.065
45.1
90.1
180.24
270.36
360.49
450.61
540.73
720.97
901.21
1351.82
1802.43
8.0"
 7.981
78.0
156.1
312.11
468.17
624.22
780.28
936.34
1248.45
1560.56
2340.84
3121.12
10.0"
 10.020
123.0
246.0
491.96
737.94
983.92
1229.90
1475.89
1967.85
2459.81
3689.71
4919.62
12.0"
 12.000
176.4
352.8
705.60
1058.40
1411.20
1764.00
2116.80
2822.40
3528.00
5292.00
7056.00
14.0"
 13.250
215.1
430.1
860.26
1290.38
1720.51
2150.64
2580.77
3441.03
4301.28
6451.92
8602.56
16.0"
 15.250
284.9
569.8
1139.56
1709.33
2279.11
2848.89
3418.67
4558.23
5697.78
8546.67
11395.56
18.0"
 17.250
364.5
729.0
1458.06
2187.08
2916.11
3645.14
4374.17
5832.23
7290.28
10935.42
14580.56
20.0"
 19.250
453.9
907.9
1815.76
2723.63
3631.51
4539.39
5447.27
7263.03
9078.78
13618.17
18157.56
24.0"
 23.250
662.2
1324.4
2648.76
3973.13
5297.51
6621.89
7946.27
10595.03
13243.78
19865.67
26487.56
30.0"
 29.250
1048.1
2096.1
4192.26
6288.38
8384.51
10480.64
12576.77
16769.03
20961.28
31441.92
41922.56
36.0"
 35.250
1522.1
3044.3
6088.56
9132.83
12177.11
15221.39
18265.67
24354.23
30442.78
45664.17
60885.56
42.0"
 41.250
2084.4
4168.8
8337.66
12506.48
16675.31
20844.14
25012.97
33350.63
41688.28
62532.42
83376.56
48.0"
 47.250
2734.9
5469.8
10939.56
16409.33
21879.11
27348.89
32818.67
43758.23
54697.78
82046.67
109395.56

Schedule 80
Velocity (fps)
Nominal
Size
Actual
I.D.
0.5
1
2
3
4
5
6
8
10
15
20
1/8"
 0.215 0.06 0.11 0.23 0.34 0.45 0.57 0.68 0.91 1.13 1.70 2.27
1/4"
 0.302 0.11 0.22 0.45 0.67 0.89 1.12 1.34 1.79 2.23 3.35 4.47
3/8"
 0.423 0.22 0.44 0.88 1.32 1.75 2.19 2.63 3.51 4.38 6.58 8.77
1/2"
 0.546 0.37 0.73 1.46 2.19 2.92 3.65 4.38 5.84 7.30 10.96 14.61
3/4"
 0.742 0.67 1.35 2.70 4.05 5.40 6.74 8.09 10.79 13.49 20.23 26.98
1"
 0.957 1.1 2.2 4.49 6.73 8.98 11.22 13.46 17.95 22.44 33.66 44.88
1.5"
 1.500 2.8 5.5 11.03 16.54 22.05 27.56 33.08 44.10 55.13 82.69 110.25
2.0"
 1.939 4.6 9.2 18.42 27.63 36.85 46.06 55.27 73.69 92.11 138.17 184.23
2.5"
 2.323 6.6 13.2 26.44 39.66 52.88 66.11 79.33 105.77 132.21 198.32 264.42
3.0"
 2.900 10.3 20.6 41.21 61.81 82.42 103.02 123.63 164.84 206.05 309.07 412.09
4.0"
 3.826 17.9 35.9 71.73