Hazen–Williams Calculator

100 L/s flowing through 1 km of 300 mm pipe with C = 130 loses 6.42347 m of head.

Hazen–Williams coefficient C:

New ductile iron or PVC 130–150, cast iron 100, old steel 80.

Pipe diameter D:

Pipe length L:

Discharge Q:

Head loss hf =

6.42347402037764 m

Precision

Full answer, then cut to fewer decimals (not rounded):

6.42347402037764 m
6.4234740203776 m
6.423474020377 m
6.42347402037 m
6.4234740203 m
6.423474020 m
6.42347402 m
6.4234740 m
6.423474 m
6.42347 m
6.4234 m
6.423 m
6.42 m
6.4 m

Hydraulic gradient hf/L: 6.42347402 m per km
Velocity V: 1.414710605 m/s

Step-by-step solution

hf = 10.67 L Q^1.852 / (C^1.852 D^4.8704)
hf = 10.67 × 1000 × 0.1^1.852 ÷ (130^1.852 × 0.3^4.8704) = 6.42347402 m

Hazen–Williams Formula

hf = 10.67 L Q^1.852 / (C^1.852 D^4.8704)

SI units: hf, L, D in m; Q in m³/s

Worked Example

100 L/s through 1 km of 300 mm pipe with C = 130:

hf = 10.67 L Q^1.852 / (C^1.852 D^4.8704)
hf = 10.67 × 1000 × 0.1^1.852 ÷ (130^1.852 × 0.3^4.8704) = 6.42347402 m

Velocity V: 1.414710605 m/s

GATE tip

C drops with age: new cast iron 130, after 20 years about 100. Design water mains on the aged C.

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Δ = 8.64 B / D

Δ in m, B in days, D in ha/cumec

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Frequently asked questions

When should Hazen–Williams not be used?

It suits water at ordinary temperatures in turbulent flow; for other fluids, small pipes or laminar flow use Darcy–Weisbach.

How sensitive is head loss to diameter?

Very: hf ∝ D^−4.87, so a 10 % larger pipe cuts the head loss by about 37 %.

Sources

The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.

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APA

Scientific Converters. (2026, October 15). Hazen–Williams Calculator. Retrieved October 29, 2026, from https://scientificconverters.com/calculators/hazen-williams-calculator/

IEEE

Scientific Converters, "Hazen–Williams Calculator," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/calculators/hazen-williams-calculator/