The Energy Converter converts energy units such as joules, calories, kilocalories, kilowatt-hours, and BTU. Enter a value in one unit and read the others with the factor and substituted arithmetic. The page converts energy quantities that are already known; it does not solve work or kinetic-energy equations from force, mass, or velocity.
Physics energy solvers compute energy from other inputs. The Energy Converter only changes the unit label on an energy amount, using audited factors such as 4.184 joules per thermochemical calorie and 3.6 × 10^6 joules per kilowatt-hour.
Convert between units of energy
The Energy Converter maps every supported unit through the joule, the SI unit of energy, then formats the target unit. Joules suit science and engineering notes. Kilowatt-hours suit electricity bills. Calories and kilocalories appear in chemistry and nutrition. BTU values appear in heating and cooling loads.
Choose source and target units, enter the number, and the Energy Converter recalculates live. Cascade mode lists joules, calories, kilocalories, kWh, and BTU from one entry so a single laboratory reading can be compared with a utility or HVAC figure without retyping.
Because energy is a scalar quantity here, the tool does not ask for time, power, or efficiency. Power converters handle watts; this page stays on energy (power integrated over time) as a standalone amount.
Convert joules to calories
One thermochemical calorie equals exactly 4.184 joules. Joules convert to thermochemical calories by dividing by 4.184. Calories convert to joules by multiplying by 4.184.
calories = joules ÷ 4.184
joules = calories × 4.184Worked example: convert 4184 joules to calories.
1. Divide by 4.184. 4184 ÷ 4.184 = 1000 calories (thermochemical).
2. Reverse check. 1000 × 4.184 = 4184 joules.
The Energy Converter labels the thermochemical calorie when that definition is active. Older "international table" calories used 4.1868 J; this page sticks to the thermochemical 4.184 J factor used in most modern science tables unless a different calorie type is explicitly selected in the unit list.
Understand the calorie and the food Calorie
The small calorie (cal) is the thermochemical calorie above. The food Calorie written with a capital C on US nutrition labels is one kilocalorie (kcal), equal to 1000 small calories. Saying a snack has "200 Calories" means about 200 kcal, or 200 × 4184 = 836,800 joules using the thermochemical factor chain.
| Label on packaging | Scientific unit | Joules (thermochemical chain) |
|---|---|---|
| 1 cal (small) | 1 cal | 4.184 J |
| 1 Calorie (food) | 1 kcal | 4184 J |
| 100 Calories | 100 kcal | 418,400 J |
Mixing capital-C food Calories with small calories without a thousand-fold factor understates or overstates energy by three orders of magnitude. The Energy Converter keeps kcal and cal as separate units so a nutrition figure and a chemistry lab figure do not share one ambiguous "calorie" field.
Convert kilowatt-hours to joules
One kilowatt-hour is the energy delivered by one kilowatt of power running for one hour. In SI units that equals 3.6 × 10^6 joules, because 1000 W × 3600 s = 3,600,000 J.
joules = kWh × 3,600,000
kWh = joules ÷ 3,600,000Worked example: convert 2 kWh to joules.
1. Multiply by 3,600,000. 2 × 3,600,000 = 7,200,000 joules.
2. Optional calorie check. 7,200,000 ÷ 4.184 ≈ 1,721,797 thermochemical calories, or about 1721.8 kcal.
Electricity bills quote kWh; lab notes quote joules. The Energy Converter bridges those scales so appliance energy and scientific energy share one audited path. BTU conversions use the page factor table the same way: enter BTU, read joules or kWh, and inspect the factor line rather than memorizing every pairwise constant.
Convert BTU and read the factor line
Heating and cooling loads often quote British thermal units. The Energy Converter routes BTU through joules using the audited BTU-to-joule factor on the unit table, then formats kWh, calories, or other targets from that joule value. Always read the factor line under the result so a hand check matches the page rather than a rounded memory figure.
Worked path for a small load: enter 1000 BTU, choose joules or kWh as the target, and confirm that multiplying back by the inverse factor recovers about 1000 BTU within display rounding. Cascade mode lists joules, kWh, and calories together so an HVAC figure and a lab figure share one entry.
Power is not energy. Watts measure power; multiplying power by time yields energy (for example, 1 kW for 1 hour equals 1 kWh). Use a power converter when the quantity is watts or horsepower; keep this page for energy amounts already stated as joules, kWh, calories, or BTU.
FAQ
How do I convert joules to calories?
To convert joules to thermochemical calories, divide joules by 4.184. For example, 4184 ÷ 4.184 = 1000 cal. The Energy Converter divides by that factor and shows the working.
How many joules are in one kilowatt-hour?
One kilowatt-hour equals 3,600,000 joules. The Energy Converter multiplies kWh by 3,600,000 to reach joules, and divides by the same figure to return kWh.
What is the difference between a calorie and a Calorie?
A small calorie (cal) equals 4.184 joules. A food Calorie (Cal) equals one kilocalorie, or 1000 small calories. The Energy Converter lists cal and kcal separately so nutrition labels and lab calories stay distinct.
How do I convert kWh to joules?
To convert kilowatt-hours to joules, multiply kWh by 3,600,000. For example, 1.5 kWh × 3,600,000 = 5,400,000 J. The Energy Converter performs that multiply on the result panel.
Is this an energy physics solver?
No. The Energy Converter only converts units of an energy quantity you already have. Physics tools that compute kinetic energy, potential energy, or work from other variables belong on separate solver pages.
Why is the calorie factor 4.184?
The thermochemical calorie is defined as 4.184 joules exactly in common scientific usage. The Energy Converter uses that definition for thermochemical calorie rows in the factor table.
Can I convert BTU to kWh?
Yes. Enter BTU as the source unit and kWh as the target. The Energy Converter routes through joules using the audited BTU-to-joule factor, then divides by 3,600,000 to reach kilowatt-hours.
How many joules are in 100 food Calories?
One hundred food Calories equal 100 kcal. Using 4184 J per kcal, that is 418,400 joules. The Energy Converter reaches the same figure when kcal is selected as the source unit.
Summary
The Energy Converter converts joules, calories, kilocalories, kilowatt-hours, and related energy units through audited factors such as 4.184 J per thermochemical calorie and 3,600,000 J per kWh. Food Calories are kilocalories, one thousand times a small calorie, and must stay labeled separately.
Every result shows the factor and working, and the page remains a unit converter rather than a physics energy equation solver.