How many joules in a kilowatt-hour?
1 kWh = 3,600,000 J = 3.6 MJ. A 1 kW device running for one hour uses exactly 1 kWh of energy.
Energy totals only (J, kWh, kcal, BTU)—not power rates. For watts, horsepower, or BTU/h, use the Power Converter. Food-label Calories are kilocalories.
Skip to energy converterConvert joules, kilojoules, calories, food Calories (kcal), watt-hours, kilowatt-hours, BTU, and electronvolts with live equivalents—private, browser-only math.
Energy totals only — for watts, hp, or BTU/h (power), use the Power Converter.
Energy measures how much work is stored or transferred, not how fast it flows. Nutrition labels quote food Calories (kilocalories), utility meters accumulate kilowatt-hours, HVAC specs still list BTU, and physics problems jump between joules and electronvolts.
This tool normalizes every value through joules, then shows equivalents across all supported units at once. That helps when a EU label shows kJ but your spreadsheet expects kcal, or when you need to compare a 2,000 kcal diet target to megajoules for an engineering report.
Food Calorie = kilocalorie (4,184 J). 1 kWh = 3.6 MJ. 1 BTU ≈ 1,055 J. Normalize through joules before comparing domains.
Concise answers for common searches — definitions, steps, and comparisons.
1 kWh = 3,600,000 J = 3.6 MJ. A 1 kW device running for one hour uses exactly 1 kWh of energy.
A food Calorie (capital C) is a kilocalorie = 4,184 J. A chemistry calorie (lowercase) is 4.184 J—off by 1,000 if you mix them.
Divide BTU joules by 3,600,000: kWh = BTU × 1,055.06 ÷ 3,600,000. Example: 10,000 BTU ≈ 2.931 kWh.
Type the amount to convert. Very small values (eV) and large values (kWh on bills) are supported.
Pick joules, kJ, cal, kcal, Wh, kWh, BTU, erg, or eV—or tap a unit row to switch the active column.
Every unit updates from a single joule baseline. The To column highlights your target unit and the 1:1 factor line.
Use Copy Result for a one-line summary, Swap to flip units, or Reset to return to 1 joule.
Common real-world scenarios where this tool saves time.
Nutritionists and fitness enthusiasts
EU labels show kcal and kJ; US labels often show only kcal. Converting keeps dietary targets in the local convention.
Engineers and HVAC professionals
US equipment is rated in BTU; European gear in kW or kWh. Normalize to one column before comparing replacements.
Physics and chemistry students
Atomic energy levels use eV; macroscopic thermodynamics uses joules. Convert at problem boundaries without manual factors.
Step-by-step chains that connect related tools for common tasks.
Input
3,600,000 JOutput
1 kWh (exact)Divide joules by 3,600,000. Utility meters use kWh because raw joules are too large for household totals.
Input
500 kcal (food Calories)Output
2,092 kJ · 2,092,000 J · 0.5816 kWhNutritional labels in Australia, Canada, and the EU show both kcal and kJ. 500 food Calories = 2,092 kJ. The Calorie on labels is always a kilocalorie.
Input
10,000 BTUOutput
≈ 2.931 kWh · ≈ 10.55 MJHVAC equipment often quotes BTU (energy). Convert to kWh before comparing with utility-meter readings or European kWh specs.
Input
2,000 kcalOutput
≈ 8.37 MJ · ≈ 2.33 kWhUseful when a report expects megajoules but meal planning still speaks in kcal.
Every unit is converted to joules first, then divided by the target unit’s joule factor. This keeps nutrition, electricity, HVAC, and physics units consistent in one table.
Formula
joules = input × (joules per source unit). result = joules ÷ (joules per target unit). Example: 1 kWh = 1 × 3,600,000 J; 500 kcal = 500 × 4,184 J = 2,092,000 J.Factors used in this tool (via joule baseline).
| Unit | In joules (J) | Notes |
|---|---|---|
| 1 J | 1 | SI base unit |
| 1 kJ | 1,000 | EU food labels, engineering |
| 1 cal (thermochemical) | 4.184 | Chemistry small calorie |
| 1 kcal / food Calorie | 4,184 | Nutrition labels |
| 1 Wh | 3,600 | Battery specs |
| 1 kWh | 3,600,000 | Utility meters |
| 1 BTU | ≈ 1,055.06 | HVAC / fuels (energy) |
BTU/h on equipment labels is power—use the power converter, not this page.
Typical contexts—not exhaustive.
| Context | Common unit |
|---|---|
| Utility bills & solar ROI | kWh |
| Food & exercise apps | kcal (Calories) |
| North American HVAC specs | BTU (energy chunk) |
| SI science & engineering | J, kJ |
| Particle / band-gap physics | eV |
Need rate of use (watts)? See the power converter.
kWh needs power × time with hours aligned to the definition (or convert via the power converter first).
Food Calorie = kilocalorie (×1000). Always check capital C on packaging.
Both are fine—pick one column in a spreadsheet and convert explicitly (1 kWh ≈ 3,412 BTU).
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A calorie (lowercase c) is the thermochemical unit: energy to heat 1 g of water by 1°C = 4.184 joules. A Calorie (capital C) on food labels is a kilocalorie = 1,000 small calories = 4,184 joules. When a label says 200 Calories, it means 200 kcal.
Divide joules by 3,600,000. Example: 3,600,000 J = 1 kWh exactly. The calculator above accepts any positive value in joules and shows kWh in the unit table.
A British Thermal Unit (BTU) is heat to raise 1 pound of water by 1°F. 1 BTU ≈ 1,055.06 J ≈ 0.293 Wh. Furnaces and fuels quote BTU; 1 ton of cooling ≈ 12,000 BTU/h (power)—convert energy vs power carefully.
1 kWh ≈ 860.4 kcal. Example: a 60 W bulb for 1 hour uses 0.06 kWh ≈ 51.6 kcal—roughly the energy in 10 g of sugar.
kW is power (rate). kWh is energy (power × time). This page converts energy totals; use the power converter when a spec says kW or BTU/h.
Mostly in particle physics, semiconductor band gaps, and spectroscopy. An eV is tiny compared to a joule—handy at atomic scale, not for billing or meal planning.
Wage and energy values are calculated in your browser and are not uploaded to EverydayTools servers.
Uses standard factors (4.184 J per thermochemical calorie, 1 kWh = 3.6 MJ, 1 BTU ≈ 1,055.06 J). Food-label Calories are kilocalories—verify regulatory definitions for compliance labeling.
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Reviewed by EverydayTools Editorial Team on 2026-07-07.
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Quick presets
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HVAC
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1 kWh = 3,600 kJ · Utility meters
Result
3,600 kJ
3,600,000 J · 3.6 MJ · 1,000 Wh · 860,420.650096 cal
1 kWh (Kilowatt-hour) = 3,600 kJ (Kilojoule)
Shortcuts: S swap · C copy
Conversion factors (SI joule baseline)
1 kWh = 3,600,000 J = 3,600 kJ
1 food Calorie (kcal) = 4,184 J
1 BTU = 1,055.0559 J
1 cal (thermochemical) = 4.184 J
Need power (kW, hp)? Power Converter
3,600 kJ