Convert Joule to British Thermal Unit

Quick answer: Joule to British Thermal Unit

1 Joule = 0.0009478171 British Thermal Unit (J → BTU). To convert joule to british thermal unit, multiply by 0.0009478171. To convert british thermal unit to joule, multiply by 1,055.056. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common joule-to-british thermal unit questions.

How to convert Joule to British Thermal Unit

To convert joule to british thermal unit, multiply the number of joule by the conversion factor 0.0009478171, because 1 J = 0.0009478171 BTU. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 BTU = 1,055.056 J, so you divide by 0.0009478171 (or multiply by 1,055.056) to turn british thermal unit back into joule.

BTU = J × 0.0009478171  ·  J = BTU × 1,055.056

1. Write down the value you want to convert, in joule.
2. Multiply it by 0.0009478171.
3. The result is the same area/length/quantity expressed in british thermal unit.

Joule to British Thermal Unit — worked examples

Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 joule is 0.004739086 british thermal unit because 5 J × 0.0009478171 = 0.004739086 BTU.

Common Joule to British Thermal Unit conversions

These are the joule-to-british thermal unit values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:

• 1 joule = 0.0009478171 british thermal unit
• 2 joule = 0.001895634 british thermal unit
• 2.5 joule = 0.002369543 british thermal unit
• 3 joule = 0.002843451 british thermal unit
• 4 joule = 0.003791268 british thermal unit
• 5 joule = 0.004739086 british thermal unit
• 6 joule = 0.005686903 british thermal unit
• 7 joule = 0.00663472 british thermal unit
• 8 joule = 0.007582537 british thermal unit
• 9 joule = 0.008530354 british thermal unit
• 10 joule = 0.009478171 british thermal unit
• 12 joule = 0.01137381 british thermal unit
• 15 joule = 0.01421726 british thermal unit
• 20 joule = 0.01895634 british thermal unit
• 25 joule = 0.02369543 british thermal unit
• 30 joule = 0.02843451 british thermal unit
• 50 joule = 0.04739086 british thermal unit
• 75 joule = 0.07108628 british thermal unit
• 100 joule = 0.09478171 british thermal unit
• 200 joule = 0.1895634 british thermal unit
• 500 joule = 0.4739086 british thermal unit
• 1000 joule = 0.9478171 british thermal unit

Joule to British Thermal Unit conversion chart (both directions)

The chart below converts joule to british thermal unit and british thermal unit to joule side by side, so it works whichever way you need. 1 joule = 0.0009478171 british thermal unit, and 1 british thermal unit = 1,055.056 joule.

Joule vs British Thermal Unit: which is bigger?

A british thermal unit is the larger unit: one british thermal unit equals 1,055.056 joules. Put another way, you need 1,055.056 joules to make a single british thermal unit.

What is a Joule? History, origin and usage

The joule is named after the English physicist James Prescott Joule (1818-1889), a Salford brewer’s son who, through painstaking experiments in the 1840s, measured the mechanical equivalent of heat and showed that work and heat are interchangeable forms of energy. The name was proposed by Wilhelm Siemens at an 1882 British Association meeting, and the joule was adopted as an international unit at the 1889 International Electrical Congress — just weeks before Joule himself died.

As the SI unit of energy, the joule underpins all of physics and engineering, measuring mechanical work, heat and electrical energy alike (one joule is also one watt-second). It appears on European food labels (usually as kilojoules), in battery specifications, and anywhere energy must be stated in coherent SI units.

One joule is roughly the energy needed to lift a small apple (about 100 grams) one metre against gravity, or the kinetic energy of a 56-gram tennis ball travelling about 6 m/s. Because one joule equals one newton-metre, the joule is dimensionally identical to the newton-metre of torque, yet the two describe different physical quantities.

What is a British Thermal Unit? History, origin and usage

The British thermal unit is the heat needed to raise one pound of water by one degree Fahrenheit, a definition rooted in pre-metric heating engineering. Despite the name, the term “British thermal unit” apparently originated in the United States before being adopted in Britain.

The BTU dominates North American heating and cooling: furnace and air-conditioner capacities are rated in BTU per hour, and natural gas is priced per million BTU (MMBtu). Air-conditioner “tonnage” is also defined through it — one ton of cooling equals 12,000 BTU per hour.

One BTU is roughly the heat from burning a single wooden kitchen match — about 1,055 joules. Several slightly different BTU definitions exist depending on the water temperature chosen, differing by up to about half a percent, which is why standards specify the “International Table” BTU.

Convert 1 Joule to other units

It can help to see a joule next to the other units it is commonly compared with. One joule (J) is equal to:

Convert 1 British Thermal Unit to other units

One british thermal unit (BTU) is equal to:

Tips for converting Joule to British Thermal Unit

• To go from joule to british thermal unit, multiply by 0.0009478171; to go back, divide by 0.0009478171 (or multiply by 1,055.056).
• For a quick mental estimate, remember that 1 joule ≈ 0.0009478171 british thermal unit, so 10 joule ≈ 0.009478171 british thermal unit.
• The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
• Both fields update live as you type — change either side to convert in that direction.

How to use this Joule to British Thermal Unit converter

Type a number into the Joule field and the equivalent in British Thermal Unit appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the British Thermal Unit field to convert the other way (british thermal unit to joule). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.

Accuracy and method

Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 J = 0.0009478171 BTU), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for joule-to-british thermal unit conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.

Sources

• NIST Special Publication 811 — Guide for the Use of the SI — publishes the exact metric equivalents of the customary units. The inch, foot, yard and mile are defined exactly in metres by the 1959 international yard-and-pound agreement, so every imperial figure on this page is exact, not rounded.
• BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.

<strong>Torque vs energy:</strong> {torqueNote}

Frequently asked questions

How many british thermal unit are in 1 joule?

1 joule = 0.0009478171 british thermal unit (BTU). To convert any number of joule to british thermal unit, multiply by 0.0009478171.

How do I convert joule to british thermal unit?

Multiply the number of joule by 0.0009478171. For example, 10 joule = 10 × 0.0009478171 = 0.009478171 british thermal unit, and 25 joule = 0.02369543 british thermal unit.

How many joule are in 1 british thermal unit?

1 british thermal unit = 1,055.056 joule. So to convert british thermal unit back to joule, multiply by 1,055.056.

What is the formula to convert joule to british thermal unit?

british thermal unit = joule × 0.0009478171. The reverse formula is joule = british thermal unit × 1,055.056.

How much is 100 joule in british thermal unit?

100 joule = 0.09478171 british thermal unit. (And 1000 joule = 0.9478171 british thermal unit.)

Which is bigger, a joule or a british thermal unit?

A british thermal unit is larger: 1 british thermal unit = 1,055.056 joule.

Is this joule to british thermal unit converter accurate?

Yes — every value is computed from the exact 0.0009478171 BTU per J factor (not rounded look-up tables), and the factors are re-verified automatically on every update.

Can I convert british thermal unit to joule too?

Yes. The converter works both ways — enter a value in either field. 1 british thermal unit = 1,055.056 joule.

Related power & energy conversions

• British Thermal Unit to Joule
• Joule to Newton-metre
• Kilowatt-hour to Joule
• Joule to Watt-hour
• Newton-metre to Joule
• Joule to Kilowatt-hour
• Calorie to Joule
• Joule to Calorie
• British Thermal Unit to Kilowatt-hour
• Kilowatt-hour to British Thermal Unit

See all power & energy conversions →