Water Pressure Drop Calculator Reference Values

Estimate water pressure drop in piping using a Hazen-Williams approximation.

Author

Prof. Rajesh Sharma

Plumbing editorial contributor

Indian agricultural economist from IARI New Delhi, advising governments on food security under climate change

Reviewed for accuracy by

Prof. Zara Khan

Plumbing content reviewer

Pakistani-British education researcher at Cambridge, evaluating digital literacy programs in South Asian rural schools

Last updatedFebruary 22, 2026

PublishedFebruary 22, 2026

Reference Value Index

This page lists 75 reference values for quick browsing and lookup.

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All Reference Values

Reference Table

Water Pressure Drop Calculator reference values
Scenario	Pressure Drop	Drop / 100 ft (psi)	Head Loss (ft)
0.75 in, 5 gpm, 50 ft (copper)	0.01 psi drop	0.019	0.022
0.75 in, 5 gpm, 100 ft (copper)	0.019 psi drop	0.019	0.044
0.75 in, 5 gpm, 150 ft (copper)	0.029 psi drop	0.019	0.066
0.75 in, 10 gpm, 50 ft (copper)	0.035 psi drop	0.069	0.08
0.75 in, 10 gpm, 100 ft (copper)	0.069 psi drop	0.069	0.16
0.75 in, 10 gpm, 150 ft (copper)	0.104 psi drop	0.069	0.239
0.75 in, 15 gpm, 50 ft (copper)	0.073 psi drop	0.146	0.169
0.75 in, 15 gpm, 100 ft (copper)	0.146 psi drop	0.146	0.338
0.75 in, 15 gpm, 150 ft (copper)	0.219 psi drop	0.146	0.507
0.75 in, 20 gpm, 50 ft (copper)	0.124 psi drop	0.249	0.288
0.75 in, 20 gpm, 100 ft (copper)	0.249 psi drop	0.249	0.575
0.75 in, 20 gpm, 150 ft (copper)	0.373 psi drop	0.249	0.863
0.75 in, 30 gpm, 50 ft (copper)	0.264 psi drop	0.527	0.609
0.75 in, 30 gpm, 100 ft (copper)	0.527 psi drop	0.527	1.218
0.75 in, 30 gpm, 150 ft (copper)	0.791 psi drop	0.527	1.826
1 in, 5 gpm, 50 ft (copper)	0.002 psi drop	0.005	0.005
1 in, 5 gpm, 100 ft (copper)	0.005 psi drop	0.005	0.011
1 in, 5 gpm, 150 ft (copper)	0.007 psi drop	0.005	0.016
1 in, 10 gpm, 50 ft (copper)	0.009 psi drop	0.017	0.02
1 in, 10 gpm, 100 ft (copper)	0.017 psi drop	0.017	0.039
1 in, 10 gpm, 150 ft (copper)	0.026 psi drop	0.017	0.059
1 in, 15 gpm, 50 ft (copper)	0.018 psi drop	0.036	0.042
1 in, 15 gpm, 100 ft (copper)	0.036 psi drop	0.036	0.083
1 in, 15 gpm, 150 ft (copper)	0.054 psi drop	0.036	0.125
1 in, 20 gpm, 50 ft (copper)	0.031 psi drop	0.061	0.071
1 in, 20 gpm, 100 ft (copper)	0.061 psi drop	0.061	0.142
1 in, 20 gpm, 150 ft (copper)	0.092 psi drop	0.061	0.212
1 in, 30 gpm, 50 ft (copper)	0.065 psi drop	0.13	0.15
1 in, 30 gpm, 100 ft (copper)	0.13 psi drop	0.13	0.3
1 in, 30 gpm, 150 ft (copper)	0.195 psi drop	0.13	0.45
1.25 in, 5 gpm, 50 ft (copper)	0.001 psi drop	0.002	0.002
1.25 in, 5 gpm, 100 ft (copper)	0.002 psi drop	0.002	0.004
1.25 in, 5 gpm, 150 ft (copper)	0.002 psi drop	0.002	0.006
1.25 in, 10 gpm, 50 ft (copper)	0.003 psi drop	0.006	0.007
1.25 in, 10 gpm, 100 ft (copper)	0.006 psi drop	0.006	0.013
1.25 in, 10 gpm, 150 ft (copper)	0.009 psi drop	0.006	0.02
1.25 in, 15 gpm, 50 ft (copper)	0.006 psi drop	0.012	0.014
1.25 in, 15 gpm, 100 ft (copper)	0.012 psi drop	0.012	0.028
1.25 in, 15 gpm, 150 ft (copper)	0.018 psi drop	0.012	0.042
1.25 in, 20 gpm, 50 ft (copper)	0.01 psi drop	0.021	0.024
1.25 in, 20 gpm, 100 ft (copper)	0.021 psi drop	0.021	0.048
1.25 in, 20 gpm, 150 ft (copper)	0.031 psi drop	0.021	0.072
1.25 in, 30 gpm, 50 ft (copper)	0.022 psi drop	0.044	0.051
1.25 in, 30 gpm, 100 ft (copper)	0.044 psi drop	0.044	0.101
1.25 in, 30 gpm, 150 ft (copper)	0.066 psi drop	0.044	0.152
1.5 in, 5 gpm, 50 ft (copper)	0 psi drop	0.001	0.001
1.5 in, 5 gpm, 100 ft (copper)	0.001 psi drop	0.001	0.002
1.5 in, 5 gpm, 150 ft (copper)	0.001 psi drop	0.001	0.002
1.5 in, 10 gpm, 50 ft (copper)	0.001 psi drop	0.002	0.003
1.5 in, 10 gpm, 100 ft (copper)	0.002 psi drop	0.002	0.005
1.5 in, 10 gpm, 150 ft (copper)	0.004 psi drop	0.002	0.008
1.5 in, 15 gpm, 50 ft (copper)	0.002 psi drop	0.005	0.006
1.5 in, 15 gpm, 100 ft (copper)	0.005 psi drop	0.005	0.012
1.5 in, 15 gpm, 150 ft (copper)	0.007 psi drop	0.005	0.017
1.5 in, 20 gpm, 50 ft (copper)	0.004 psi drop	0.009	0.01
1.5 in, 20 gpm, 100 ft (copper)	0.009 psi drop	0.009	0.02
1.5 in, 20 gpm, 150 ft (copper)	0.013 psi drop	0.009	0.029
1.5 in, 30 gpm, 50 ft (copper)	0.009 psi drop	0.018	0.021
1.5 in, 30 gpm, 100 ft (copper)	0.018 psi drop	0.018	0.042
1.5 in, 30 gpm, 150 ft (copper)	0.027 psi drop	0.018	0.062
2 in, 5 gpm, 50 ft (copper)	0 psi drop	0	0
2 in, 5 gpm, 100 ft (copper)	0 psi drop	0	0
2 in, 5 gpm, 150 ft (copper)	0 psi drop	0	0.001
2 in, 10 gpm, 50 ft (copper)	0 psi drop	0.001	0.001
2 in, 10 gpm, 100 ft (copper)	0.001 psi drop	0.001	0.001
2 in, 10 gpm, 150 ft (copper)	0.001 psi drop	0.001	0.002
2 in, 15 gpm, 50 ft (copper)	0.001 psi drop	0.001	0.001
2 in, 15 gpm, 100 ft (copper)	0.001 psi drop	0.001	0.003
2 in, 15 gpm, 150 ft (copper)	0.002 psi drop	0.001	0.004
2 in, 20 gpm, 50 ft (copper)	0.001 psi drop	0.002	0.002
2 in, 20 gpm, 100 ft (copper)	0.002 psi drop	0.002	0.005
2 in, 20 gpm, 150 ft (copper)	0.003 psi drop	0.002	0.007
2 in, 30 gpm, 50 ft (copper)	0.002 psi drop	0.004	0.005
2 in, 30 gpm, 100 ft (copper)	0.004 psi drop	0.004	0.01
2 in, 30 gpm, 150 ft (copper)	0.007 psi drop	0.004	0.015

Frequently Asked Questions

Frequently asked questions for Water Pressure Drop Calculator and its reference values.

What method is used to estimate pressure drop?

This calculator uses a Hazen-Williams based approximation, commonly applied to water flow in building piping.

Why does smaller pipe increase pressure drop?

Smaller inside diameter increases velocity and friction effects, producing higher pressure loss at the same flow.

What does the C-factor represent?

The Hazen-Williams C-factor models pipe roughness, where higher C values indicate smoother pipe and lower friction loss.

Is this suitable for final engineering design?

Use it for preliminary sizing and comparisons. Final designs should follow code, manufacturer data, and complete hydraulic calculations.

Methodology and Review

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