Therms Calculator: convert therms instantly. Full formula, unit table, and worked example.
An energy converter switches between joules (J), kilojoules (kJ), kilowatt-hours (kWh), calories (cal), kilocalories (kcal / food Calories), British Thermal Units (BTU), electronvolts (eV), and other energy units used across physics, engineering, nutrition, and utility billing. Energy units vary dramatically by application: food energy is measured in kcal (Calories), electricity in kWh, heating in BTU, and physics in joules — all measuring the same fundamental quantity at vastly different scales.
Use related pages when the same quantity appears in another convention: compare BTU Calculator,kWh to MJ Calculator, and Energy Conversion Calculator while keeping the unit definition, reference conditions, and rounding rule visible. Conversion is a transparent change of representation, not evidence that the underlying measurement or model is accurate.
For energy, temperature, pressure, and digital data, a familiar label can hide different boundaries. Check whether the value describes a physical quantity, a rate, a storage capacity, a transfer speed, or a derived result. Preserve the original input and the unrounded intermediate value, especially when the converted number will feed another formula, a purchase, a technical specification, or a safety or regulatory decision.
Check the direction as well as the magnitude: converting from a larger unit to a smaller unit usually increases the numerical value, while the reverse usually decreases it. That simple sense check catches many inverted factors. Then compare the result with a familiar reference, such as a litre, kilogram, kilometre, degree, pound, megabyte, or standard atmospheric pressure. If the comparison is surprising, inspect the source unit, prefix, regional convention, and whether the calculator expects a rate or a total before accepting the displayed number.
Some relationships are exact by definition, while others are rounded references or depend on conditions. A temperature interval is not interpreted exactly like an absolute temperature, a decimal data prefix may be decimal or binary, and energy or pressure values can be tied to a stated standard. Derived quantities need the same care: square units require the conversion factor to be squared, and rates require both the numerator and denominator to be identified. Keep those definitions with the result so another reader can reproduce the conversion without guessing what the label meant.
1 kilocalorie (kcal) = 4,184 J = 1.163 Wh = 3.968 BTU
1 kilowatt-hour (kWh) = 3,600,000 J = 3,412.14 BTU = 859.845 kcal
1 BTU = 1,055.06 J = 0.000293 kWh = 0.252 kcal
1 joule = 1 W·s = 0.000239 kcal = 0.000000278 kWh = 6.242×10¹⁸ eV
1 therm = 100,000 BTU = 29.307 kWh (US natural gas billing unit)
A cheeseburger: ~550 kcal = 2,301 kJ = 0.640 kWh. A 60W light bulb running 1 hour: 0.06 kWh = 51.5 kcal = 204.7 BTU. Average US home electricity use per day: ~30 kWh = 25,784 kcal = 102,364 BTU. 1 gallon of gasoline energy content: ~132 MJ = 36.7 kWh = 125,000 BTU = 31,500 kcal. 1 pound of TNT equivalent: 4.184 MJ = 1.162 kWh = 1,000 kcal (the original definition of the kilocalorie).
Energy billing standards for electricity (kWh) and natural gas (therms, CCF, cubic metres) are regulated by state public utility commissions. Nutritional Calorie values on food labels are regulated by the FDA. Scientific energy measurements should follow NIST standards.