Toolarithm

Unit Converter

Power Converter

Named power units. Clear runtime calculations.

Convert a power quantity

Named power factors. Explicit elapsed intervals.

Signed decimal, scientific notation, fraction or mixed number. Zero is valid; negative power follows your declared transfer direction.

Optional runtime projection

Runtime assumes constant or matching average power. Cooling capacity and shaft output do not establish purchased electrical input. Apply tariffs only to matching input energy; additional charges and losses are excluded.

View power results
Precision and report

Decimals support twenty significant digits, eighty characters and written exponents from negative thirty through thirty. Fractions support one hundred digits per component and two hundred forty characters per field. Display precision does not improve measured energy, timing, equipment ratings or an assumed tariff.

Worked examples

Power in watts

Pt≈745.699871582 WP_t\approx745.699871582\,\mathrm W

Exact numerical conversion under named unit definitions. Display rounding does not establish measurement accuracy or change a device rating.

Power conversion record

Entered power

Ps=1.00000000000 hpmechP_s=1.00000000000\,\mathrm{hp}_{\mathrm{mech}}

Normalized power

PW≈745.699871582 WP_{\mathrm W}\approx745.699871582\,\mathrm W

Power in kilowatts

PkW≈0.745699871582 kWP_{\mathrm{kW}}\approx0.745699871582\,\mathrm{kW}

Source-to-target factor

k≈745.699871582k\approx745.699871582

Positive and negative power follow your declared direction of transfer. Refrigeration tons express cooling capacity; horsepower may describe shaft output. Unit conversion alone does not infer electrical input, efficiency or operating conditions.

Power in every supported convention

All twenty-six rows represent the same signed rate of energy transfer. Every definition and exact numerical certificate stays in copied text and CSV when this table is hidden.

The same power in twenty-six named conventions
Power conventionConverted power
Watts≈ 745.699871582 W\approx\,745.699871582\,\mathrm W
Kilowatts≈ 0.745699871582 kW\approx\,0.745699871582\,\mathrm{kW}
Megawatts (capital M)≈ 0.000745699871582 MW\approx\,0.000745699871582\,\mathrm{MW}
Mechanical horsepower1.00000000000 hpmech1.00000000000\,\mathrm{hp}_{\mathrm{mech}}
International Table Btu per hour≈ 2544.43357764 BtuIT/h\approx\,2544.43357764\,\mathrm{Btu}_{\mathrm{IT}}/\mathrm h
Foot-pound-force per second550.000000000 ft lbf/s550.000000000\,\mathrm{ft\,lbf}/\mathrm s
Thermochemical calories per second≈ 178.226546745 calth/s\approx\,178.226546745\,\mathrm{cal}_{\mathrm{th}}/\mathrm s
Nanowatts≈ 7.45699871582×1011 nW\approx\,7.45699871582\times10^{11}\,\mathrm{nW}
Microwatts≈ 7.45699871582×108 μW\approx\,7.45699871582\times10^{8}\,\mathrm{\mu W}
Milliwatts (lowercase m)≈ 745699.871582 mW\approx\,745699.871582\,\mathrm{mW}
Gigawatts≈ 7.45699871582×10−7 GW\approx\,7.45699871582\times10^{-7}\,\mathrm{GW}
Terawatts≈ 7.45699871582×10−10 TW\approx\,7.45699871582\times10^{-10}\,\mathrm{TW}
Metric horsepower (PS)≈ 1.01386966542 hpmetric\approx\,1.01386966542\,\mathrm{hp}_{\mathrm{metric}}
Electric horsepower≈ 0.999597683086 hpelectric\approx\,0.999597683086\,\mathrm{hp}_{\mathrm{electric}}
International Table Btu per minute≈ 42.4072262941 BtuIT/min\approx\,42.4072262941\,\mathrm{Btu}_{\mathrm{IT}}/\mathrm{min}
International Table Btu per second≈ 0.706787104901 BtuIT/s\approx\,0.706787104901\,\mathrm{Btu}_{\mathrm{IT}}/\mathrm s
Foot-pound-force per minute33000.0000000 ft lbf/min33000.0000000\,\mathrm{ft\,lbf}/\mathrm{min}
Foot-pound-force per hour1980000.00000 ft lbf/h1980000.00000\,\mathrm{ft\,lbf}/\mathrm h
Thermochemical kilocalories per second≈ 0.178226546745 kcalth/s\approx\,0.178226546745\,\mathrm{kcal}_{\mathrm{th}}/\mathrm s
Thermochemical kilocalories per hour≈ 641.615568283 kcalth/h\approx\,641.615568283\,\mathrm{kcal}_{\mathrm{th}}/\mathrm h
International Table calories per second≈ 178.107354443 calIT/s\approx\,178.107354443\,\mathrm{cal}_{\mathrm{IT}}/\mathrm s
International Table kilocalories per hour≈ 641.186475995 kcalIT/h\approx\,641.186475995\,\mathrm{kcal}_{\mathrm{IT}}/\mathrm h
Ergs per second≈ 7.45699871582×109 erg/s\approx\,7.45699871582\times10^{9}\,\mathrm{erg}/\mathrm s
Kilogram-force meters per second76.0402249068 kgf m/s76.0402249068\,\mathrm{kgf\,m}/\mathrm s
US refrigeration tons≈ 0.212036131470 TRUS\approx\,0.212036131470\,\mathrm{TR}_{\mathrm{US}}
Joules per second≈ 745.699871582 J/s\approx\,745.699871582\,\mathrm J/\mathrm s

Step-by-step power calculation

  1. 1. Normalize the named power convention

    Multiply by the named watt factor. Metric and electric horsepower remain separate from mechanical horsepower, and each thermal rate retains its stated convention.

    PW≈745.699871582 WP_{\mathrm W}\approx745.699871582\,\mathrm W

  2. 2. Divide by the destination watt factor

    Every table row uses the unrounded watt quantity. Display significant figures affect presentation only.

    Pt≈745.699871582 WP_t\approx745.699871582\,\mathrm W
What Can You Create?

Convert a power rating, inspect an average or project energy

Compare named power specifications

Translate watts, SI prefixes, three horsepower conventions, mechanical work rates and named thermal rates. The complete table compares the same physical rate without hiding the distinctions between input, output and cooling capacity.

Recover average power from energy

Use energy measured over a known elapsed interval to find its average transfer rate. Normalize the energy and interval independently so the quotient can be reviewed alongside the resulting watts and chosen destination.

Keep runtime arithmetic attached

Project a stated constant or matching average power over a separately entered runtime. Add an optional flat energy rate when it applies to that same input-energy boundary, and retain the model exclusions in the report.

Power formulas and worked examples

Convert through the watt

Let PsP_s be the entered source number, and let fsf_s and ftf_t be the watts represented by one source or target unit. Multiply by the first factor and divide by the second.

PW=Psfs,Pt=PWftP_{\mathrm W}=P_s f_s,\qquad P_t=\frac{P_{\mathrm W}}{f_t}

Keep horsepower definitions separate

The mechanical work-rate definition uses the international foot and defined pound-force. Metric horsepower instead uses kilogram-force under defined standard gravity. Their numerical difference remains after conversion to the same watt unit.

1 hpmech=550 ft lbf/s=745.69987158227022 W1\,\mathrm{hp}_{\mathrm{mech}}=550\,\mathrm{ft\,lbf}/\mathrm s=745.69987158227022\,\mathrm W1 hpmetric=75 kgf m/s=735.49875 W1\,\mathrm{hp}_{\mathrm{metric}}=75\,\mathrm{kgf\,m}/\mathrm s=735.49875\,\mathrm W

Find average power from a measured energy transfer

Suppose an energy meter records 16 kW h16\,\mathrm{kW\,h} over 8 h8\,\mathrm h. Divide quantities from that same interval. This quotient gives an average; it does not reveal the highest instantaneous reading.

P‾=Et=16 kW h8 h=2 kW=2000 W\overline P=\frac{E}{t}=\frac{16\,\mathrm{kW\,h}}{8\,\mathrm h}=2\,\mathrm{kW}=2000\,\mathrm W

Project runtime energy and matching energy-only charges

If that 2 kW2\,\mathrm{kW} is also the actual average over a new 2 h2\,\mathrm h runtime, the projected energy is 4 kW h4\,\mathrm{kW\,h}. At a matching flat input-energy rate of 0.200.20 currency units per kilowatt-hour, the energy-only amount is 0.800.80 currency units.

Eproj=Ptproj=2 kW×2 h=4 kW hE_{\mathrm{proj}}=Pt_{\mathrm{proj}}=2\,\mathrm{kW}\times2\,\mathrm h=4\,\mathrm{kW\,h}C=Eproj,kW hr=4×0.20=0.80 currency unitsC=E_{\mathrm{proj,kW\,h}}r=4\times0.20=0.80\,\mathrm{currency\ units}

Recognize a cooling-capacity unit

A US refrigeration ton converts a named cooling rate into watts. The result does not determine the electricity used to deliver that cooling; that requires additional equipment performance information.

1 TRUS=12000 BtuIT/h≈3516.85284207 W1\,\mathrm{TR}_{\mathrm{US}}=12000\,\mathrm{Btu}_{\mathrm{IT}}/\mathrm h\approx3516.85284207\,\mathrm W
Why Users Love This Tool

Make power comparisons with definitions you can inspect

Conventions stay identifiable

  • All seven original power identifiers and the mechanical-horsepower default remain available.
  • Mechanical, metric and electric horsepower have distinct labels and watt factors.
  • Thermochemical and International Table heat rates remain separate, with a clearly defined US refrigeration ton.

The numerical record stays complete

  • Exact rational arithmetic prevents intermediate display rounding from changing downstream conversions.
  • Swapping uses the exact target quantity rather than the rounded number on screen.
  • Complete copying and CSV preserve every unit row, factor, numerical certificate and active assumption even when report sections are hidden.
Perfect For

Useful for specification reviews, thermal comparisons and learning

Device and motor specification checks

Convert an explicitly named rating while keeping electrical input separate from useful output. A unit change can make values comparable numerically, but matching duty, efficiency and test conditions still requires information from the equipment documentation.

Heating and cooling reference work

Translate heat-transfer rates and refrigeration capacity with explicit thermal standards. Inspect whether a source uses a thermochemical calorie, an International Table calorie or an IT Btu before comparing reported capacities.

Students practicing dimensions

Follow why energy divided by elapsed time produces average power, and why power multiplied by runtime produces energy. Explore the difference between lowercase milli and uppercase mega without losing the original unrounded quantity.

How It Works

How it works in three quick steps.

1

Choose direct power or an energy measurement

Enter a signed power quantity with its named convention, or enter the energy transferred during a strictly positive elapsed measurement interval. Identify whether the quantity describes electrical input, shaft output or heat transfer.

2

Inspect the conversion and any runtime projection

Choose a destination, review normalized watts and compare all supported conventions. Optionally enter a separate nonnegative runtime to project energy at constant or matching average power. Apply a flat energy rate only to the appropriate matching energy quantity.

3

Keep definitions and assumptions with the result

Copy the complete report or LaTeX working, export all rows as CSV, share active validated settings or print the selected report to PDF. Retain horsepower type, thermal standard, measurement interval and projection assumptions when comparing specifications.

Download & Print

Download and print the power calculation with its context

Copy text, formulas or a settings link

Copy the complete plain-text report or properly delimited LaTeX steps. Share links include validated active inputs and report preferences. Inactive energy measurements, projection values and price buffers are replaced by defaults before sharing.

Export every convention as CSV

Download a quoted UTF-8 record containing all twenty-six power rows, exact numerical certificates and named factors. Measurement intervals, projected energy and any charge assumptions stay attached, including working that is hidden on screen.

Print a selected report or save PDF

Choose whether to display the table, exact ratio and working, then use Print / Save PDF. Select portrait paper and inspect the browser preview. The report retains model assumptions while controls and the article are omitted. Extremely long exact ratios stay available in text and CSV.

FAQ

Frequently Asked Questions

How many watts are in mechanical horsepower?
This converter defines one mechanical horsepower as 550 ft lbf/s550\,\mathrm{ft\,lbf}/\mathrm s. Using the international foot and defined pound-force gives exactly 745.69987158227022 W745.69987158227022\,\mathrm W. The displayed result may round this number according to your selected significant figures, but subsequent calculations use its full rational value. The original one-horsepower example remains the default. Select the mechanical convention explicitly when your source specification uses this definition; a shortened horsepower label alone may leave the intended standard uncertain.
Why do metric and electric horsepower give different results?
Horsepower is a family of named conventions. Metric horsepower uses 75 kgf m/s75\,\mathrm{kgf\,m}/\mathrm s, giving 735.49875 W735.49875\,\mathrm W with defined standard gravity. The electric horsepower convention here is 746 W746\,\mathrm W. Neither number replaces the mechanical definition. These are unit choices rather than motor-efficiency estimates. Before comparing two ratings, also check whether each describes input or output power and whether the test conditions match. Changing the unit cannot reconcile different measurement boundaries or rating procedures.
Can this converter turn kilowatt-hours into kilowatts?
Energy becomes average power only when you supply the elapsed interval over which that energy was transferred. Choose the energy-and-time method and use P‾=E/t\overline P=E/t. For example, sixteen kilowatt-hours transferred over eight hours corresponds to an average of two kilowatts. The interval must be strictly positive; dividing zero energy by zero time is still undefined. This average does not establish instantaneous peaks, startup demand or the maximum rating of the equipment involved.
What does a US refrigeration ton mean here?
A US refrigeration ton represents a cooling heat-transfer rate of 12000 BtuIT/h12000\,\mathrm{Btu}_{\mathrm{IT}}/\mathrm h. It is a unit of power, despite using the word ton, and should not be interpreted as a mass. Cooling capacity is also different from the electrical power used to produce that cooling. Converting capacity into kilowatts does not tell you the electricity input or operating cost. That further calculation requires applicable performance information and operating conditions, which this unit converter does not infer.
Which calorie and British thermal unit standards are supported?
The original calorie-per-second identifier uses the thermochemical calorie, with 1 calth=4.184 J1\,\mathrm{cal}_{\mathrm{th}}=4.184\,\mathrm J. Separate International Table calorie choices use 1 calIT=4.1868 J1\,\mathrm{cal}_{\mathrm{IT}}=4.1868\,\mathrm J. All Btu rates on this page use the International Table Btu. The displayed names and exported definitions keep those conventions explicit. A kilocalorie includes one thousand calories of its own named standard. Check the source document before selecting a thermal unit whose abbreviation does not identify its convention.
Can I calculate energy use and cost from a device wattage?
Enable the runtime projection and provide a nonnegative elapsed duration. The model uses Eproj=PtprojE_{\mathrm{proj}}=Pt_{\mathrm{proj}}, so the supplied power must be constant or represent the average during that new interval. A nameplate maximum is not automatically an operating average. A matching flat energy rate can then supply energy-charge arithmetic in your own currency units. Fixed fees, demand charges, taxes, price tiers, exchange rates and equipment losses are excluded. Cooling capacity or shaft output must not be substituted for purchased electrical input.
Are zero, negative values and fractions accepted?
Direct power and measured energy may be zero or signed. A negative value follows a transfer direction that you declare, such as a modeled signed difference, rather than describing a negative equipment rating by default. The measurement interval must remain positive. Projection runtime and an optional flat rate may be zero but cannot be negative. Decimal, scientific, fraction and mixed-number inputs are supported within the stated field limits. Exact arithmetic preserves these entered numbers before display rounding, while validation rejects undefined or unsupported expressions.
Can I convert apparent power, decibels or torque into watts here?
This page converts linear power units. Apparent power in volt-amperes needs an appropriate relationship to real power, including the applicable power factor. A logarithmic level such as dBm uses a reference and logarithmic transformation rather than one linear multiplier. Torque needs rotational motion information before it determines mechanical power. Those quantities are therefore outside this converter's unit list. Use a dedicated electrical or torque tool and retain its assumptions instead of treating every similar-looking label as an interchangeable power unit.
About This Tool

About this Power Converter

This Power Converter organizes rates of energy transfer around the watt. Its purpose is to make the unit definition and physical boundary easy to retain when a specification moves between documents. The initial example converts one mechanical horsepower into watts, preserving the original page workflow. Additional conventions extend that workflow to small electronic power scales, large plant ratings, mechanical work rates and explicitly named heating or cooling capacities.

The direct conversion uses a source watt factor and a destination watt factor. These definitions are applied with rational arithmetic, and the selected significant figures affect only the displayed number. A full numerical certificate remains available in exported records. This is exact arithmetic on the entered model, rather than a claim that a measured quantity or published device rating has unlimited accuracy. The result therefore belongs with the original source, measurement precision and convention.

The energy-and-time method answers a different question: what average rate corresponds to an energy transfer measured during a stated interval? Both quantities must describe the same period. A separate runtime projection may then apply the calculated or directly entered power to a new interval, but doing so introduces an explicit constant-power or matching-average assumption. The interface does not silently substitute equipment maximums, infer operating cycles or estimate losses.

Keeping these boundaries visible matters when comparing motors, heaters and refrigeration systems. Shaft output and cooling capacity may both be expressed in watts without being purchased electrical input. An optional energy rate is therefore arithmetic attached to an appropriate matching energy quantity, with its exclusions carried into saved reports. Complete copying, CSV, share links and printable output help preserve that reasoning when the calculation is reviewed later.

Editorial Transparency

Who maintains this page

Ownership and review

Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.

Methodology

Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.

Read the editorial methodology

Dates and sources

Review dates change only after a substantive method or content check.

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