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Power Converter

Converts power between watts (W to GW), mechanical horsepower (745.69987158227 W), metric horsepower (735.49875 W), BTU per hour, foot-pounds per second, kcal/h and tons of refrigeration.

When to use

You need engine, motor, heater or air-conditioner power in another unit, e.g. hp to kW, kW to BTU/h or tons of refrigeration to kW.

Do not use when: You need energy (use energy) or to compute power from work and time or voltage and current (use work-power or electric-power).

Formula

result = value × factor, factor = (1 from_unit in W) / (1 to_unit in W)

hp is the mechanical (imperial) horsepower of 550 ft·lbf/s; hp_metric (PS, cv, ch) is 75 kgf·m/s. Electrical horsepower (746 W exactly) and boiler horsepower (9809.5 W) are not included.

Inputs

Parameter	Type	Required	Description
`value`	number	yes	Amount to convert, expressed in from_unit.
`from_unit`	enum: W \| kW \| MW \| GW \| hp \| hp_metric \| BTU/h \| ft_lbf/s \| kcal/h \| ton_refrigeration	yes	Unit of the input value. Accepted symbols: W, kW, MW, GW, hp, hp_metric, BTU/h, ft_lbf/s, kcal/h, ton_refrigeration; spelled-out names and common abbreviations are accepted too.
`to_unit`	enum: W \| kW \| MW \| GW \| hp \| hp_metric \| BTU/h \| ft_lbf/s \| kcal/h \| ton_refrigeration	yes	Unit to convert into (same symbols as from_unit).

Outputs

Output	Type	Description
`result`	number	Converted value expressed in to_unit (rounded to 6 decimals; see result_text for very small or very large values).
`result_text`	string	The conversion as text with 6 significant figures, e.g. "5 mi = 8.04672 km".
`formula`	string	Relation used, e.g. "1 mi = 1.609344 km".
`factor`	number	Multiplier from from_unit to to_unit (result = value × factor); absent for non-linear conversions.
`conversion_table`	object	The input value expressed in every supported power unit (6 significant figures), keyed by unit symbol.

Example

100 hp to kilowatts: {"value":100,"from_unit":"hp","to_unit":"kW"} → {"result":74.569987,"formula":"1 hp = 0.7456998716 kW","conversion_table":{"BTU/h":254443,"hp_metric":101.387}}

2 kW to BTU per hour: {"value":2,"from_unit":"kW","to_unit":"BTU/h"} → {"result":6824.283,"conversion_table":{"hp":2.68204,"W":2000}}

GET https://tttkmbb.com/api/v1/calculate/power?value=100&from_unit=hp&to_unit=kW

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/power (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/power · Markdown: https://tttkmbb.com/conversion/power.md · JSON definition: https://tttkmbb.com/conversion/power.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="power"
OpenAPI operationId: convert_power
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

Mechanical or metric horsepower?

hp is the mechanical horsepower (745.7 W) used in the US and UK; hp_metric is the metric PS/cv/ch (735.5 W) used in European car specifications. They differ by 1.4%.

What is a ton of refrigeration?

The cooling rate that freezes one short ton of water in 24 hours: 12,000 BTU/h = 3516.85 W (3.517 kW).

Related calculators

Energy Converter — Power × time gives energy (kWh, J).
Work & Power Calculator — Compute power from work and time.
Electric Power Calculator — Power from voltage, current and resistance.