Pump Power Calculator (kW / HP)

Hydraulic, shaft and electrical power for a pumping duty with pump and motor efficiency.

Flow rate (L/s)Total head (m)Specific gravityPump efficiency (%)Motor efficiency (%)

Hydraulic power (kW)

Shaft (brake) power (kW)

Electrical input (kW)

Quick check: kW ≈ Q(L/s) × H(m) / 102 / η. A 20 L/s × 30 m duty at 70% efficiency needs ~8.4 kW shaft — motor next size up: 11 kW.

Formula

P_hyd = ρ·g·Q·H; P_shaft = P_hyd/η_p; P_elec = P_shaft/η_m

References: Hydraulic Institute — pump power relationships

Pump Power Calculator (kW / HP) is a free pump power for pump engineers, plumbers and plant designers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.

About Pump Power Calculator (kW / HP)

Hydraulic, shaft and electrical power for a pumping duty with pump and motor efficiency. The calculation implements P_hyd = ρ·g·Q·H; P_shaft = P_hyd/η_p; P_elec = P_shaft/η_m (Hydraulic Institute — pump power relationships). Quick check: kW ≈ Q(L/s) × H(m) / 102 / η. A 20 L/s × 30 m duty at 70% efficiency needs ~8.4 kW shaft — motor next size up: 11 kW.

How to use Pump Power Calculator (kW / HP)

1Enter Flow rate in L/s.
2Enter Total head in m.
3Enter Specific gravity.
4Enter Pump efficiency in %.
5Read Hydraulic power, Shaft (brake) power, Electrical input instantly — no submit button needed.
6Need US units? Flip the SI/Imperial toggle and every field converts.

Why use Pump Power Calculator (kW / HP)?

✓Implements the standard formula — P_hyd = ρ·g·Q·H; P_shaft = P_hyd/η_p; P_elec = P_shaft/η_m
✓Reference cited on-page: Hydraulic Institute — pump power relationships
✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
✓Live worked example: the substitution recomputes from your numbers
✓Runs entirely in your browser — nothing uploaded, free forever

Frequently asked questions

What formula does the Pump Power Calculator (kW / HP) use?+

It computes P_hyd = ρ·g·Q·H; P_shaft = P_hyd/η_p; P_elec = P_shaft/η_m, per Hydraulic Institute — pump power relationships. The formula is displayed under the result along with a worked example substituted with your own inputs.

What should I keep in mind when using this calculator?+

Quick check: kW ≈ Q(L/s) × H(m) / 102 / η. A 20 L/s × 30 m duty at 70% efficiency needs ~8.4 kW shaft — motor next size up: 11 kW.

Can I use this for pump selection?+

Use it to establish the duty (flow, head, NPSH, power) and then pick a pump whose curve passes through that point near best efficiency. The tool gives you the engineering numbers a supplier will ask for.

Is the Pump Power Calculator (kW / HP) free to use?+

Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.

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