Energy Converter

Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and electronvolts. Three tiers: Quick, Extended with real-world energy comparisons, and Professional with Eskom tariff calculator and fuel calorific values.

⚡ Quick Calculator Get a fast estimate

From

Conversion Result

1 kJ = 0.000278 kWh

Joules (J)

1000

Calories (cal)

239.00574

Kilocalories (kcal)

0.23900574

Watt-hours (Wh)

0.27777778

How to Use This Converter

Select your source and target energy units, type a value in either field, and the conversion updates instantly. Kilocalories (kcal) are what food labels call "Calories" (with a capital C). kWh is used for electricity billing in South Africa — your Eskom or municipal bill shows consumption in kWh.

The Extended Calculator shows real-world energy comparisons (lightbulb hours, driving distances). The Professional Calculator adds power × time energy calculation with Eskom cost estimates and fuel calorific values.

Need more detail?

📊 Extended Calculator More options, charts, and scenario comparison

Value

From

Result

3,6 MJ

In Joules

3 600 000 J

In kWh

Energy Comparison

Electrical Units

Unit	Value
Joule (J)	3 600 000
Kilojoule (kJ)	3 600
Megajoule (MJ)	3,6
Watt-hour (Wh)	1 000
Kilowatt-hour (kWh)	1
Megawatt-hour	0,001

Energy Conversion Reference

Unit	In Joules
1 Joule (J)	1 J
1 Calorie (cal)	4.184 J
1 Kilocalorie (kcal)	4 184 J
1 Watt-hour (Wh)	3 600 J
1 Kilowatt-hour (kWh)	3 600 000 J
1 BTU	1 055.06 J

Need full precision?

🔬 Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown

Energy Conversion (All Units)

Value

From

Unit	Value
Joule (J)	3 600 000
Kilojoule (kJ)	3 600
Megajoule (MJ)	3,6
Gigajoule (GJ)	0,004
Calorie (cal)	860 400
Kilocalorie (kcal)	860,4
Watt-hour (Wh)	1 000
kWh	1
MWh	0,001
BTU	3 412
Therm (US)	0,034
TOE	0

Power × Time = Energy Calculator

Power

Power Unit

Runtime

Time Unit

Energy Used

19,2 kWh

In MJ

69,12

Eskom cost

R 41,66

SA Electricity Cost (Eskom Homepower Tariff ~2025)

Monthly Usage (kWh)

Estimated Monthly Bill

R 925

Avg rate

R 2,31/kWh

Tier	Rate/kWh
Block 1 (0–350 kWh)	R 2.17
Block 2 (351–600 kWh)	R 3.31
Block 3 (601+ kWh)	R 4.11

Approximate. Exact tariff depends on municipality and meter type.

Calorific Values of Common Fuels

Fuel	MJ/unit	kWh/unit
Petrol (per L)	34.2	9,5
Diesel (per L)	35.8	9,944
LPG/Propane (per L)	25.3	7,028
Natural Gas (per m³)	38.5	10,69
Coal (per kg)	24	6,667
Wood (per kg)	15	4,167
Hydrogen (per kg)	142	39,44
Charcoal (per kg)	29	8,056

Frequently Asked Questions

A kilowatt-hour is the energy consumed by a 1 000-watt device running for one hour. It is the unit used on South African electricity bills. A typical South African household uses 600–1 200 kWh per month. At Eskom rates, 1 kWh costs approximately R2.50–R3.50 depending on your municipality.

1 kilocalorie (kcal) = 1 000 small calories (cal). Food labels use "Calories" (capital C) to mean kilocalories. So a chocolate bar with 250 Calories actually contains 250 kcal = 250 000 cal = 1 046 000 J of energy.

1 kWh = 3 600 000 joules (3.6 MJ). This is because: 1 kW = 1 000 W = 1 000 J/s, and 1 hour = 3 600 seconds. So 1 kWh = 1 000 × 3 600 = 3 600 000 J.

A British Thermal Unit (BTU) is the amount of energy needed to heat one pound of water by 1°F. It is used primarily in the US for air conditioning and heating equipment ratings. In South Africa, air conditioners are rated in BTU or kW — a 12 000 BTU unit ≈ 3.5 kW.

Energy Converter

How to Use This Converter

Energy Conversion Reference

Frequently Asked Questions

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