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Energy & power

Energy, power, force, electricity, and fuel measures.

Choose the tool whose inputs and output match your task. Check each calculator’s assumptions and limitations before using its result.

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These converters handle energy, power, and related electrical units, from appliance ratings to engineering notes. Start with the energy converter for joules, calories, kilowatt-hours, and BTUs — the capacity to do work. The power converter measures how fast energy is transferred in watts, kilowatts, mechanical horsepower, and megawatts. When a motor plate lists watts and a spec sheet uses horsepower, the watts to horsepower calculator bridges the two, and the electric current converter aligns amperes, milliamperes, and microamperes for circuit work. Pick the quantity you are measuring first. More conversion tools are in the Conversion collection.

10 of 10 calculators

Energy & power10 calculators

Currency Converter Calculator

Convert indicative amounts among USD, EUR, GBP, JPY, CHF, and CAD using the calculator's fixed sample exchange factors, with clear guidance on rates, fees, and related money tools.

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Verified

dBm to Watts Calculator

Convert dBm to watts and milliwatts with the logarithmic decibel-milliwatt formulas used in RF, wireless, electronics, and signal-power work.

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Verified

Electric Current Converter

Convert electric current between amperes, milliamperes, and microamperes with SI-based factors, electronics examples, reference tables, and practical circuit cautions.

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Verified

Energy Converter

Convert energy among joules, small calories, kilowatt-hours, and International Table BTU with specified unit conventions.

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Verified

Joules to Volts Calculator

Calculate volts from joules and coulombs using voltage equals energy per unit charge, with required charge input.

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Verified

Power Converter

Convert power among watts, kilowatts, mechanical horsepower, and megawatts with dimensional factors and clear rounding.

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Verified

RMS to Watts Converter

Calculate watts from RMS voltage or RMS current when load resistance or impedance is known, with clear AC power assumptions.

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Verified

Torque to Mechanical Horsepower Calculator

Calculate mechanical horsepower from torque and RPM using the exact ft·lbf and N·m constants in the calculator, with engine examples and RPM cautions.

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Verified

Unix Time Converter

Convert Unix epoch timestamps in seconds to UTC dates and convert UTC date text back to Unix time for logs, APIs, databases, and scripts.

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Verified

Watts to Horsepower Calculator: W to Mechanical HP

Convert watts to mechanical horsepower (W to hp) with the exact 745.69987158227022 W per hp factor, worked examples, motor-rating context, and accuracy notes.

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Verified

Frequently asked questions

Is a small calorie the same as a food Calorie?
No. This converter uses the small calorie, where one calorie equals 4.184 joules. A food Calorie, often written with a capital C on nutrition labels, is a kilocalorie, so it equals 1000 small calories or 4184 joules total here.
How many BTU are in one kilowatt-hour?
Using the International Table BTU factor of 1055.05585262 joules, one kilowatt-hour is about 3412.14 BTU_IT. The calculator divides 3,600,000 joules by that factor.
Can this converter handle negative energy values?
No. The current form rejects negative values and converts only nonnegative energy amounts. That matches ordinary metering, heating, and stored-energy comparisons. In advanced physics, negative energy changes can be meaningful, but this unit converter is not designed for signed energy bookkeeping.

More in Conversion

The same topic in other collections.

Electric Current vs Cable SizeCompare the electric current converter's ampere, milliampere, and microampere unit conversion with the cable size calculator's voltage-drop worksheet that consumes amps for preliminary conductor sizing.Energy Converter vs Power ConverterCompare the energy and power converters: joules, calories, kilowatt-hours, and BTU measure energy, while watts, kilowatts, horsepower, and megawatts measure how fast it flows — and when to use each.Ohm's Law vs Electric Current ConverterCompare the Ohm's Law calculator with the electric current converter: solving voltage, current, or resistance and power for resistive circuits versus relabeling amperes, milliamperes, and microamperes.RMS to Watts vs dBm to WattsCompare two ways of reaching watts from an electrical signal: RMS voltage or current with a load in ohms versus a logarithmic dBm level referenced to 1 mW — for audio and AC power versus RF power.Sound Level Converter vs dBm to Watts CalculatorCompare two meanings of 'dB': the sound level converter's loudness scales (dB, phon, sone at 1 kHz) versus the dBm to watts calculator's absolute RF signal power referenced to 1 mW.Unix Time vs Julian Date ConverterCompare Unix time and Julian Date: two ways to represent a moment as a single number — and which one your logs, APIs, or astronomy records should use.Watts to Horsepower vs Torque to HorsepowerCompare the two mechanical horsepower calculators: converting a watt rating directly versus computing horsepower from torque and RPM with the same unit constants.

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