PhysicsCalcs
Units & Conversions

Power Converter

Convert watts to horsepower, horsepower to watts, kW to hp, BTU/h to kW, tons of refrigeration, VA to W, and more with verified factors.

Interactive converter

Power Converter

Convert watts, kilowatts, horsepower, BTU per hour, tons of refrigeration, calories per second, volt-amperes, and more.

Power is normally non-negative. kW is power; kWh is energy. Very large or small results may use scientific notation.

From
To

Result

Enter a value and click Convert to see the conversion.

Quick Guide

  • Enter a power value and select from/to units.
  • Use presets for W↔hp, Btu/h↔kW, or TR↔kW.
  • VA units assume power factor = 1 — see warning in results.

Table of Contents

Key Takeaways

  • Power is the rate of energy transfer or work done per unit time.
  • The watt (W) is the SI unit of power; 1 W = 1 J/s.
  • 1 kW = 1,000 W; 1 mechanical hp ≈ 745.7 W.
  • 1 Btu IT/h ≈ 0.293071 W; 1 refrigeration ton ≈ 3.51685 kW.
  • kW is power; kWh is energy — they are not the same.
  • VA and W are equal only when power factor = 1.

What Is a Power Converter?

It converts power values between SI watts, joules per time, horsepower types, BTU-based thermal power, calorie rates, mechanical power, apparent volt-amperes, and HVAC units using watts internally.

For energy (not power), see the Energy Conversion Calculator. For electrical P = VI calculations, use the Electrical Power Calculator. Compare rates with the Time Converter.

How to Use the Power Converter

  1. 1Enter a power value (scientific notation such as 1e6 is supported).
  2. 2Select the from and to units, or switch to All units mode.
  3. 3Click Convert — the page scrolls to your result automatically.
  4. 4Review warnings for VA/kVA (power factor = 1 assumed) and approximate units.
  5. 5Use presets for common pairs like W ↔ hp or Btu/h ↔ kW.

Power Formula

P=E/tP = E / t

P = power, E = energy, t = time. SI definition: 1 W = 1 J/s.

Watts, Kilowatts, and Megawatts

1 kW = 1,000 W; 1 MW = 1,000,000 W; 1 GW = 10⁹ W. Kilowatts rate appliances and motors; megawatts and gigawatts describe grid-scale generation.

Horsepower Units

Mechanical hp (550 ft·lbf/s) ≈ 745.7 W. Metric hp/PS = 735.49875 W. Electrical hp = 746 W. Boiler hp = 9809.5 W. Each type is labeled separately in the converter.

BTU per Hour and Thermal Power

BTU is energy; Btu/h is power. 1 Btu IT/h ≈ 0.293071 W. MBH = 1,000 Btu/h in HVAC. Thermochemical and IT BTU variants are distinguished.

Tons of Refrigeration

1 TR = 12,000 Btu IT/h ≈ 3,516.85 W ≈ 3.51685 kW. Used for cooling capacity, not mass.

VA vs W

Volt-amperes measure apparent power. Watts measure real power. In AC: W = VA × PF. This converter treats VA as W only when PF = 1. Use the Power Factor Calculator, kVA to kW Calculator, or kW to kVA Calculator for AC loads.

Power vs Energy

A 1 kW device running 2 hours uses 2 kWh of energy. Power is rate; energy is total amount transferred.

Common Power Conversions

UnitWattsNotes
1 kW1,000 WSI kilowatt
1 hp (mechanical)≈ 745.7 W550 ft·lbf/s
1 PS (metric hp)735.49875 WEuropean motor rating
1 Btu IT/h≈ 0.293 WHVAC thermal power
1 TR≈ 3,516.85 W12,000 Btu IT/h cooling

Examples

1 kW

1 kW = 1,000 W.

1 mechanical hp

1 hp ≈ 745.699871582 W.

1 Btu/h

1 Btu IT/h ≈ 0.293071 W.

1 TR

1 ton of refrigeration ≈ 3,516.85 W.

Common Mistakes

Confusing kW and kWh. Treating Btu and Btu/h as the same. Assuming all horsepower units match. Treating VA as always equal to W. Confusing refrigeration ton with mass ton.

Limitations

Fixed conversion factors; regional horsepower and calorie variants may differ. VA-to-W assumes PF = 1. Not for safety-critical HVAC or electrical design without professional verification.

FAQ

What does a Power Converter do?›

It converts a power value from one unit to another using watts as the internal reference.

What is the SI unit of power?›

The watt (W). One watt equals one joule per second.

How many watts are in a kilowatt?›

1 kW = 1,000 W exactly.

How many watts are in one horsepower?›

1 mechanical horsepower ≈ 745.699871582 W. Metric horsepower (PS) = 735.49875 W.

Is horsepower always the same?›

No. Mechanical, metric, electrical, boiler, and water horsepower have different definitions.

How many watts are in 1 BTU/h?›

1 Btu IT/h ≈ 0.293071 W.

What is a ton of refrigeration?›

A cooling power unit equal to 12,000 Btu IT/h ≈ 3.51685 kW. It is not a mass unit.

Is kW the same as kWh?›

No. kW is power (rate). kWh is energy (total amount).

Is VA the same as W?›

Only when power factor = 1. In AC circuits, real power W = VA × power factor.

How do I convert BTU/h to kW?›

Multiply Btu/h by 0.000293071, or divide by 3,412.141633. Example: 12,000 Btu/h ≈ 3.51685 kW.

How do I convert horsepower to watts?›

Multiply mechanical hp by 745.699871582, or use the W ↔ hp preset. Example: 2 hp ≈ 1,491.4 W.

What is MBH in HVAC?›

MBH usually means 1,000 Btu IT/h, not megabytes or million Btu/h.

Sources

  1. BIPM: SI Brochure
  2. NIST SP 811
Manish Kumar

Author & technical reviewer

Manish Kumar

PhysicsCalcs tools are reviewed with an educational focus: clear formulas, transparent assumptions, and practical context for students and science learners.

Learn more about Manish