Conversion Formula
Divide BTU by 3,412.142 to get kilowatt-hours. Air conditioner and furnace ratings in BTU become directly comparable with electricity consumption in kWh.
Complete Guide to BTU to Kilowatt-hours Conversion
What is a BTU?
A British Thermal Unit (BTU) is the energy required to raise one pound of water by one degree Fahrenheit. It remains the working unit of the North American heating, ventilation and air conditioning industry and of natural gas and heating oil markets.
What is a Kilowatt-hours?
A kilowatt-hour (kWh) is one kilowatt of power sustained for one hour — the unit on every electricity bill and the standard measure of battery and solar capacity.
How the Conversion Works
One BTU is 1,055.06 joules. A kilowatt-hour is 3,600,000 joules, so dividing gives 3,412.142 BTU per kWh. HVAC ratings usually express power as BTU per hour, in which case dividing by 3,412.142 gives kilowatts of thermal output.
Why This Conversion Matters
Heat pump and air conditioner catalogues quote capacity in BTU/h while electricity is metered in kWh. Without this conversion you cannot check whether a unit is correctly sized for a room, or estimate what it will cost to run.
Scientific Context
The BTU is defined relative to the specific heat capacity of water, which varies slightly with temperature. This is why several BTU definitions exist. The International Table BTU fixes the value at 1,055.05585262 J for engineering consistency.
Step-by-Step Conversion Guide
Follow these steps to convert btu to kilowatt-hours manually:
Start with your value in btu
Example: You want to convert 5000 BTU
Apply the conversion formula
Use the formula: kWh = BTU ÷ 3,412.142
Calculate the result
5000 BTU = 1.4654 kWh
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Divide BTU by 3,412.142 to get kilowatt-hours. Air conditioner and furnace ratings in BTU become directly comparable with electricity consumption in kWh.
Common Conversions
| BTU (BTU) | Kilowatt-hours (kWh) | Kilowatt-hours → BTU |
|---|---|---|
| 1000 | 0.2931 | 1000 kWh = 3412142 BTU |
| 3412 | 1 | 3412 kWh = 11642228.504 BTU |
| 5000 | 1.4654 | 5000 kWh = 17060710 BTU |
| 9000 | 2.6376 | 9000 kWh = 30709278 BTU |
| 12000 | 3.5169 | 12000 kWh = 40945704 BTU |
| 18000 | 5.2753 | 18000 kWh = 61418556 BTU |
| 24000 | 7.0337 | 24000 kWh = 81891408 BTU |
| 36000 | 10.5506 | 36000 kWh = 122837112 BTU |
| 60000 | 17.5843 | 60000 kWh = 204728520 BTU |
| 100000 | 29.3071 | 100000 kWh = 341214200 BTU |
When You'll Need This Conversion
Air conditioner sizing
Translate a BTU/h cooling rating into kilowatts to check it matches the room heat load.
Heat pump specification
Compare North American BTU ratings with European kW ratings when selecting equipment.
Energy audits
Normalise gas (BTU/therms) and electricity (kWh) into one unit for whole-building analysis.
Thermodynamics coursework
Convert between imperial and SI energy units in heat transfer problems.
Pro Tips for Accurate Conversions
Divide BTU/h by 3,412 for kW
This single step makes any American HVAC spec sheet readable to a European installer.
Watch for the missing "per hour"
Retail listings say "12,000 BTU air conditioner" but always mean 12,000 BTU/h.
Use COP or SEER for running cost
BTU output ÷ efficiency = electrical input. Never assume output equals consumption.
Common Mistakes to Avoid
Treating BTU output as electricity consumption
A heat pump moves several times more heat than the electricity it consumes.
Electrical input (kW) = thermal output (kW) ÷ COP.
Mixing BTU and BTU/h
One is energy, the other is power. Multiplying by hours twice is a common sizing error.
BTU/h × hours = BTU of energy delivered.
Using 3,400 as a shortcut for precise work
The 0.35% error is fine for a quick estimate but not for load calculations or billing.
Use 3,412.142 for anything that will be specified or invoiced.
History & Background
The BTU dates to the 19th-century steam engineering tradition, where water and Fahrenheit were the natural references. It survived the metric transition because North American gas and HVAC infrastructure standardised on it.
Key Milestones
The BTU comes into use in British and American steam engineering.
The International Steam Table conference standardises the IT BTU value.
The IT BTU is fixed at 1,055.05585262 joules for engineering use.
US energy policy debates popularise the "quad" — one quadrillion BTU — as a national energy unit.
Global Usage Today
BTU dominates US, Canadian and Middle Eastern HVAC markets. Europe, Asia and Australia specify the same equipment in kilowatts, which is why cross-market conversion is constant.
Frequently Asked Questions
Related Guides & Articles
View allMetric vs Imperial: The Complete Guide to Measurement Systems
The world is divided between two major measurement systems: metric and imperial. Understanding the d...
The Fascinating History of Temperature Scales
Temperature is something we experience every day, yet the scales we use to measure it have fascinati...
The International System of Units (SI): The Language of Science
The International System of Units (SI) is the modern metric system and the world most widely used sy...
The Complete Guide to Unit Conversion: From Basics to Mastery
Unit conversion is the essential skill that bridges the gap between different measurement systems. W...
Want to learn more about energy conversions?
Browse all energy articles →People Also Convert
Related calculators users frequently visit alongside btu to kilowatt-hours.
Last verified: April 2026. All conversion factors are based on internationally defined standards.