Energy Unit Converter

Energy appears as joules on a datasheet, kilowatt-hours on an electricity bill, calories on a thermal spec and BTU on an HVAC unit — four scales for one quantity. This converter moves exactly between them with no approximation.

Convert energy unit units

Value

From

Why energy units collide

Energy spans tiny to huge: from the electron-volt (1.602×10⁻¹⁹ J) of a single particle to the kilowatt-hour (3.6×10⁶ J) of a plant bill, with the calorie (4.184 J) and the BTU (1055 J) in between. The thermal units (cal, kcal, BTU) are exact multiples by definition, so the converter is exact.

The only discipline is the unit that fits the scale: joules for physics, kWh for electrical and plant energy, calories for thermal and nutrition, BTU for HVAC. Convert rather than carry an awkward exponent through a calculation.

Which unit where

Joules and kilojoules are the SI language of physics and process energy; kilowatt-hours rule electrical billing and motor duty; calories and kcal describe heat and thermal loads; BTU is the HVAC and heating unit. Pick the unit your method writes in, then convert.

Complete conversion reference

Convert 1 unit to	J	kJ	cal	kcal	Wh	kWh	BTU	eV
1 J	1	0.001	0.239006	0.000239006	0.000277778	2.77778e-07	0.000947817	6.24151e+18
1 kJ	1000	1	239.006	0.239006	0.277778	0.000277778	0.947817	6.24151e+21
1 cal	4.184	0.004184	1	0.001	0.00116222	1.16222e-06	0.00396567	2.61145e+19
1 kcal	4184	4.184	1000	1	1.16222	0.00116222	3.96567	2.61145e+22
1 Wh	3600	3.6	860.421	0.860421	1	0.001	3.41214	2.24694e+22
1 kWh	3.6e+06	3600	860421	860.421	1000	1	3412.14	2.24694e+25
1 BTU	1055.06	1.05506	252.164	0.252164	0.293071	0.000293071	1	6.58514e+21
1 eV	1.60218e-19	1.60218e-22	3.82929e-20	3.82929e-23	4.45049e-23	4.45049e-26	1.51857e-22	1

Instruments for this measurement

S3000CG

Gauge pressure transmitter

0–0.6 … 0–60 MPa

SE10A

Electromagnetic flowmeter, 24V DC

Lining PTFE/PU · DN10–1200

SG61

Coriolis mass flowmeter

Direct mass & density

Process Measurement

Flow, pressure, level & temperature

Electromagnetic / vortex / TX

All 195+ Products

Full instrument catalogue

Filter by application

Models shown are representative families, not a complete catalogue. Send us your application, water analysis and installation constraints and we will match instruments to it.

Frequently asked

How many joules in a kilowatt-hour?

Exactly 3 600 000 J (1 kWh = 3.6×10⁶ J), because 1 Wh = 3600 J. This is the bridge between electrical billing (kWh) and SI energy (J), and the converter applies it exactly.

What is 1 cal in joules?

Exactly 4.184 J for the thermochemical calorie; 1 kcal = 4184 J. The converter keeps calories, kcal and joules so you can move between thermal and SI energy directly.

Is BTU the same as a joule?

No. One BTU is about 1055 J (1055.06 J). BTU is the HVAC and heating unit; convert to joules or kWh for any cross-discipline energy balance.

Why do bills use kWh but datasheets use J?

Electricity is metered and billed in kWh, while instrument and physics datasheets state joules or kJ. Convert at the boundary so a duty or efficiency calc uses one consistent energy unit.

This page performs exact unit arithmetic with no physical assumption beyond the stated reference (for example mH₂O assumes water near 4 °C, and pH follows its logarithmic definition). It is a working aid, not a substitute for the measurement method named in your permit.