CFS to GPM Conversion Calculator – Convert Cubic Feet Per Second to GPM

Our CFS to GPM calculator is designed to convert water flow rates from cubic feet per second (CFS) to gallons per minute (GPM).

Let’s say you’re an engineer working on a river diversion project. Your hydrological survey reports a flow rate of 3.5 CFS, but your pump specifications are listed in GPM. Rather than performing manual calculations, you can input 3.5 into a CFS to GPM calculator and instantly receive the equivalent value of 1,570.8 GPM, allowing you to select appropriate equipment without conversion headaches.

CFS to GPM Calculator

CFS Converted to	GPM
1	448.83
2	897.66
3	1346.49
4	1795.32
5	2244.15
6	2692.98
7	3141.81
8	3590.64
9	4039.47
10	4488.31
11	4937.14
12	5385.97
13	5834.80
14	6283.63
15	6732.46
16	7181.29
17	7630.12
18	8078.95
19	8527.78
20	8976.62
21	9425.45
22	9874.28
23	10323.11
24	10771.94
25	11220.77
26	11669.60
27	12118.43
28	12567.26
29	13016.09
30	13464.92
31	13913.75
32	14362.58
33	14811.41
34	15260.24
35	15709.08
36	16157.91
37	16606.74
38	17055.57
39	17504.40
40	17953.23
41	18402.06
42	18850.89
43	19299.72
44	19748.55
45	20197.38
46	20646.21
47	21095.04
48	21543.87
49	21992.70
50	22441.53
51	22890.37
52	23339.20
53	23788.03
54	24236.86
55	24685.69
56	25134.52
57	25583.35
58	26032.18
59	26481.01
60	26929.84
61	27378.67
62	27827.50
63	28276.33
64	28725.16
65	29173.99
66	29622.82
67	30071.65
68	30520.48
69	30969.32
70	31418.15
71	31866.98
72	32315.81
73	32764.64
74	33213.47
75	33662.30
76	34111.13
77	34559.96
78	35008.79
79	35457.62
80	35906.45
81	36355.28
82	36804.11
83	37252.94
84	37701.77
85	38150.61
86	38599.44
87	39048.27
88	39497.10
89	39945.93
90	40394.76
91	40843.59
92	41292.42
93	41741.25
94	42190.08
95	42638.91
96	43087.74
97	43536.57
98	43985.40
99	44434.23
100	44883.07
200	89766.14
300	134649.21
400	179532.28
500	224415.35
600	269298.42
700	314181.49
800	359064.56
900	403947.63
1000	448830.70

CFS to GPM Conversion Formula

GPM = CFS × 448.8326

One cubic foot contains 7.48052 gallons, and when converting from seconds to minutes, we multiply by 60:

7.48052 gallons/cubic foot × 60 seconds/minute = 448.8312 ≈ 448.83 gallons per minute for each cubic foot per second

For practical purposes, the conversion factor is often rounded to 448.8.

Example: If you measure a flow rate of 2.25 CFS from a water source: GPM = 2.25 CFS × 448.8 = 1,009.8 GPM

This means a water source flowing at 2.25 cubic feet per second delivers approximately 1,010 gallons every minute – critical information for sizing pipes, pumps, or treatment systems.

How to convert cubic feet per second to gpm

1. Identify your starting flow rate in cubic feet per second (CFS)
2. Multiply this value by the conversion factor 448.8
3. Record your result as gallons per minute (GPM)

Example: A small stream has been measured at 0.75 CFS. To convert this to GPM: 0.75 CFS × 448.8 = 336.6 GPM

What is CFS and GPM?

CFS (cubic feet per second) is a unit of volumetric flow rate representing one cubic foot of water passing a specific point in one second. It’s commonly used in:

• Hydrology and river flow measurements
• Flood monitoring and prediction
• Large water resource management
• Environmental studies

GPM (gallons per minute) measures the volume of water in gallons flowing past a point in one minute. It’s typically used in:

• Plumbing and residential water systems
• Irrigation and sprinkler design
• Pump specifications and selection
• Swimming pool circulation systems

Example 1: Converting chlorine concentration A municipal water treatment plant reports chlorine levels of 2.5 mg/L Conversion: 2.5 mg/L = 2.5 ppm

Example 2: Converting dissolved oxygen A lake water sample contains 8.7 mg/L of dissolved oxygen Conversion: 8.7 mg/L = 8.7 ppm

Example 3: Converting calcium hardness Well water analysis shows calcium hardness of 152 mg/L Conversion: 152 mg/L = 152 ppm

Sources

• U.S. Geological Survey (USGS) – Water Science School: Water Measurement Units
• Environmental Protection Agency (EPA) – How We Monitor Water Quality