Earth Bondhon
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Rojony Khatun Author
Rojony Khatun
CalculatorToolsProjectExpert
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Małgorzata Koperska, MD Steven Wooding
Last updated: September 30, 2025

Horsepower Calculator: kW, Watts, Torque & RPM Converter

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Horsepower Calculator

Convert between horsepower, kW, watts, torque, and RPM. Supports mechanical/electrical HP, single- and three-phase, plus quick HP↔kW conversions.

torque to hp calculator

Power can also be found from torque and speed: HP = 5252 / (T(lb·ft) × RPM) or in metric terms power, kW (T(N·m) × RPM) / 9550; kW / 0.746 = HP. Power factor and Efficiency should be included for motors.

Formula & Table Summary:

  • HP = kW ÷ 0.746; kW = 0.746 × HP
  • kW = (TN·m × RPM) ÷ 9550
  • HP = (Tlb·ft × RPM) ÷ 5252
  • 1φ: Pin(kW) = V × I × PF ÷ 1000
  • 3φ: Pin(kW) = √3 × V × I × PF ÷ 1000
  • Pout = η × Pin

Inputs: torque & RPM or kW/HP; optional V, I, PF, phase, η (motors). Outputs: kW, HP, and notes for sanity checks.

mechanical horsepower tool

Being a horsepower calculator, it converts power between horsepower (hp), kilowatts (kW), and watts (W) and calculates the HP given the torque and speed. Torque values can be entered in Nm or lb ft to give mechanical power, or values of kW or HP to quickly convert two ways (1 hp = 0.746 kW). Electrical input/output can be estimated using voltage, current, power factor, and either single-phase or three-phase motor efficiency. The tool offers the following standard variations: mechanical horsepower (imperial), metric power (kW), and water horsepower in hydraulic applications. Use it to size motors, verify nameplate ratings, compare alternatives, and reality-check field measurements. A concise/compact formula/table and sample table aid students, electricians, and engineers to verify results visually. Created to load quickly and to rank on low-competitive, calculator-based searches and remain accurate and practical.

electrical horsepower

CaseInputkWHP
1T=40 N·m, RPM=15006.288.42
2T=120 N·m, RPM=180022.6230.33
310 kW (given)10.0013.41
43φ: 415V, 20A, PF=0.85, η=0.9011.0014.76

Frequently Asked Questions - Horsepower Calculator:

How do I convert kW to horsepower?

Divide kW by 0.746 to get HP.

How do I get HP from torque and RPM?

HP = T(lb·ft)×RPM/5252 or kW = T(N·m)×RPM/9550, then HP = kW/0.746.

What is mechanical vs electrical horsepower?

Mechanical HP is shaft power; electrical HP is based on electrical input/output including PF and efficiency.

Is 1 HP exactly 746 W?

1 hp is defined as 745.7 W; calculators typically use 0.746 kW for simplicity.

How do I include efficiency?

Multiply electrical input kW by efficiency to estimate shaft output kW before converting to HP.

How do I convert watts to HP?

HP = W / 745.7.

Can I use N·m for torque?

Yes—use kW = T(N·m)×RPM/9550, then convert to HP.

What is water horsepower?

Water HP = (Flow×Head×γ)/(746×η); it estimates hydraulic shaft power at pumps/turbines.

Why does PF matter for motors?

PF affects input kW from V and I; lower PF raises current for the same real power.

What RPM gives 1 HP at 10 lb·ft?

RPM ≈ 5252×HP/T = 5252×1/10 ≈ 525 RPM.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.