Energy Hub · 12 Units · 6 Modes

Energy Unit Converter

Convert joules, kWh, BTU, calories and 8 more energy units instantly — then go further: estimate electricity cost, food energy, fuel equivalents, and audit your home's usage.

12units

5calculators

16FAQs

0servers

1Quick Energy Converter

Instant conversion across all 12 energy units — joules to kWh, BTU to kWh, kcal to kJ, and more. The formula updates live.

Value

From

—

≡Conversion factors (per unit, in joules)

Exact factors this converter uses. Sources in the methodology section.

Unit	Symbol	Joules per unit

2Energy Cost Calculator

kWh × tariff = your bill. Pick a preset appliance or enter your own watts and usage.

Power (watts)

Hours per day

Days

Tariff (per kWh)

Currency

— kWh

costs —

Formula: kWh = watts × hours × days ÷ 1,000 · cost = kWh × tariff. AC, fridge and lamp presets use typical ratings.

⚖Appliance comparison (30 days)

How common appliances compare at your tariff — live, updates with the tariff above.

Appliance	kWh/mo	Cost/mo	Share

3Food Energy: kcal ↔ kJ

Food-label "Calories" are kilocalories. Convert both ways, then see how long it takes to burn them off.

Kilocalories (kcal)

Kilojoules (kJ)

2,092 kJ

= 500 kcal — formula: kJ = kcal × 4.184

🏃Burn it off (MET-based, simplified)

How many minutes of activity burn a given amount of energy? Uses the standard MET formula: kcal/min = MET × 3.5 × weight(kg) ÷ 200.

Energy to burn (kcal)

Body weight (kg)

Activity

— min

Simplified estimate. Real calorie burn varies with speed, terrain, fitness, and body composition — treat this as a planning figure, not a medical one.

4Battery & Fuel Equivalents

What does a kWh "weigh" in the real world? Enter electrical energy and see it as gasoline or natural gas.

Energy (kWh)

Conversion factors (vintage): 1 US gallon of gasoline = 33.7 kWh (EPA/DOE gallon gasoline equivalent, used for MPGe ratings) · 1 m³ natural gas ≈ 10.55 kWh (higher-heating-value basis) · 1 US gallon = 3.78541 L. Gas energy content varies by supplier — planning estimate.

5Mini Home Energy Audit

List your appliances — watts, hours per day, quantity — and get monthly kWh, cost, and saving tips. Educational, not a professional audit.

Days per month

Tariff (per kWh)

Currency

— kWh/mo

≈ — per month · kWh/day

Appliance	kWh/day	kWh/mo	Share

💡Quick-win saving tips

Educational pointers — the biggest bars in the table above are where savings hide.

Cooling: set AC to 24–26 °C; each degree lower adds roughly 6–10% to cooling energy.
Lighting: swap remaining bulbs for LEDs — ~80% less energy for the same brightness.
Standby: TVs, chargers and set-top boxes sip power 24/7; a switchable power strip kills it.
Fridge: keep coils clean and the door seal tight; every extra opening costs compressor cycles.
Laundry & iron: full loads, cold wash where possible; iron in batches while the plate is hot.
Know your tariff: if your utility has off-peak rates, shift washing and water heating there.

Educational only — not a professional energy audit. For wiring, solar sizing, or tariff disputes, consult a licensed professional.

Worked examples

Three fully worked conversions — every number follows the factors above.

Example 1 — 10,000 BTU → kWh (air-conditioner rating)

1 BTU(IT) = 1,055.06 J, so 10,000 BTU = 10,000 × 1,055.06 = 10,550,600 J.
1 kWh = 3,600,000 J, so divide: 10,550,600 ÷ 3,600,000 = 2.9307 kWh.

10,000 BTU ≈ 2.93 kWh

Example 2 — Monthly cost of a 1,200 W air conditioner

Energy = 1,200 W × 8 h/day × 30 days ÷ 1,000 = 288 kWh.
At $0.15/kWh: 288 × 0.15 = $43.20 per month.

288 kWh → $43.20/month

Example 3 — A 500 kcal meal in kJ, and running it off

500 kcal × 4.184 = 2,092 kJ.
Running (9.8 MET) at 70 kg burns 9.8 × 3.5 × 70 ÷ 200 = 12.0 kcal/min.
500 ÷ 12.0 = 41.6 minutes of running (simplified estimate).

500 kcal = 2,092 kJ ≈ 42 min running

Methodology

Formulas, factor sources, and scope boundaries — so you know exactly what this hub does and does not do.

Core formulas

result = value × fromFactor ÷ toFactor — every unit conversion is a ratio of joule factors.
E(kWh) = P(W) × t(h) ÷ 1,000 — energy from power and time.
cost = kWh × tariff — electricity cost.
kcal/min = MET × 3.5 × weight(kg) ÷ 200 — simplified exercise estimate, labelled as such in the tool.

Conversion factors & sources

Factor	Value used	Source
1 cal (thermochemical)	4.184 J exact	ISO 31-4 / NIST
1 eV	1.602176634×10⁻¹⁹ J exact	SI (2019 redefinition)
1 BTU (International Table)	1,055.06 J	Steam Tables convention
1 therm (US)	100,000 BTU = 105.506 MJ	US gas billing convention
1 ft·lbf	1.3558179483314004 J exact	Definition (0.3048 m × 4.4482216152605 N)
1 toe	41.868 GJ	IEA / OECD
1 gal gasoline	33.7 kWh	EPA / DOE gallon gasoline equivalent
1 m³ natural gas	≈ 10.55 kWh (HHV)	Industry HHV convention

Scope boundaries (anti-cannibal)

vs. energy-units (legacy converter): that tool converts one number between two units. This hub keeps the full 12-unit converter and adds five application calculators — electricity cost with appliance comparison, food energy with exercise equivalents, battery/fuel equivalents, and a mini home energy audit — plus methodology, sources, and worked examples.
vs. electrical-unit-converter (#282): #282 covers electrical base quantities — volts, amps, ohms, watts, farads, henries — plus Ohm's law, resistor color codes, and wire ampacity. This hub covers energy itself (joules and derivatives: kWh, BTU, calories, eV, toe) and its applications: cost, food, fuel, home usage. Energy is the joule family; #282 is the volt/amp family.
vs. appliance-energy-calculator (#80): #80 is the deep appliance tool — a 62-appliance DOE/ENERGY STAR wattage database, standby presets, bill builder, tariff-slab builder, and LED-savings module. This hub's Cost and Audit modes are quick estimators (single flat tariff, editable rows) meant to answer "what does energy cost" inside the unit hub — for a full appliance-by-appliance bill breakdown with tiered tariffs, use #80.
vs. energy-conv / energy-units (legacy slugs): thin one-dimensional converters. This hub is the comprehensive energy reference: full 12-unit converter plus cost, food, fuel, and audit calculators with sources and worked examples.
vs. thin per-pair pages (e.g. RapidTables' ~150 one-pair pages): this single hub answers every pair in one instant converter instead of one page per pair.

All computation is deterministic and runs locally in your browser. No accounts, no tracking of inputs, no external requests.

Frequently asked questions

Short answers to the most searched energy-conversion questions.

How many joules are in a kWh?

One kilowatt-hour equals exactly 3,600,000 joules (3.6 megajoules). The derivation: 1 kWh = 1,000 watts × 3,600 seconds, and 1 watt = 1 joule per second, so 1,000 × 3,600 = 3,600,000 J. To convert joules to kWh, divide by 3,600,000.

How many BTUs are in a kWh?

One kWh equals about 3,412.14 BTU (International Table). The conversion: 1 BTU_IT ≈ 1,055.06 J, and 1 kWh = 3,600,000 J, so 3,600,000 ÷ 1,055.06 ≈ 3,412.14. To convert BTU to kWh, divide by 3,412.14; to go the other way, multiply.

How do I convert kcal to kJ?

Multiply kilocalories by 4.184. For example, 500 kcal × 4.184 = 2,092 kJ. This uses the thermochemical calorie (1 cal = 4.184 J exactly). Note the food-label "Calorie" (capital C) is actually a kilocalorie, so a 500-Calorie meal is 500 kcal = 2,092 kJ.

What is the difference between kW and kWh?

Kilowatts (kW) measure power — the rate at which energy is used or produced at an instant. Kilowatt-hours (kWh) measure energy — the total amount used over time. A 1 kW heater running for 2 hours consumes 2 kWh. Your electricity bill charges for kWh, not kW.

What is a BTU?

A British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit. The International Table BTU used here equals 1,055.06 joules. BTUs are common in the US for heating/cooling ratings (e.g., a 12,000 BTU air conditioner ≈ 3.52 kWh of cooling energy).

What is a therm?

A therm (US) is 100,000 BTU, about 105.5 megajoules or 29.3 kWh. Natural gas is commonly billed in therms in the United States. One therm of gas contains roughly the same energy as 29.3 kWh of electricity — useful when comparing gas vs. electric heating costs.

What is a tonne of oil equivalent (toe)?

A tonne of oil equivalent (toe) is a standardised energy unit equal to 41.868 gigajoules (about 11.63 MWh), defined by the IEA/OECD. It lets analysts compare national energy statistics across fuels — oil, gas, coal, and electricity — on one scale.

What is an electron volt (eV)?

An electron volt is the energy one electron gains crossing a 1-volt electric potential, exactly 1.602176634×10⁻¹⁹ joules (SI 2019). It is the standard energy unit in atomic and particle physics because everyday units like joules are far too large at that scale.

How many kWh are in a gallon of gasoline?

About 33.7 kWh per US gallon, the EPA/DOE "gallon gasoline equivalent" used for comparing EV efficiency (MPGe). So a 60 kWh EV battery holds roughly the energy of 1.8 gallons of gasoline — the efficiency difference is why EVs travel much farther per kWh.

How do I calculate my electricity cost?

Multiply energy used (kWh) by your tariff: cost = kWh × price per kWh. Energy in kWh = watts × hours ÷ 1,000. Example: a 1,200 W air conditioner running 8 hours/day for 30 days uses 1,200 × 8 × 30 ÷ 1,000 = 288 kWh; at $0.15/kWh that costs $43.20.

How many minutes of running burn 500 calories?

Roughly 40–45 minutes for a 70 kg person, using the simplified MET formula (kcal/min = MET × 3.5 × weight ÷ 200) with running at 9.8 METs: 500 ÷ 12.0 ≈ 41.6 minutes. This is a simplified estimate — real burn varies with speed, terrain, fitness, and body composition.

How many kWh are in a cubic meter of natural gas?

About 10.55 kWh per cubic meter (higher-heating-value basis). So 100 kWh of heat equals roughly 9.5 m³ of gas. Actual energy content varies by gas composition and supplier, so treat this as a planning estimate, not a billing figure.

What is the difference between this hub and the energy-units converter?

The legacy energy-units tool is a one-dimensional unit converter: enter a number, pick two units. This hub is a complete energy workspace: the same 12-unit converter plus an electricity cost calculator with appliance comparisons, a food-energy (kcal/kJ) tool with exercise equivalents, battery/fuel equivalents (gasoline gallons, natural gas m³), and a mini home energy audit — each with formulas, sources, and worked examples.

How is this different from the electrical-unit-converter?

The electrical-unit-converter (#282) covers electrical base quantities — volts, amps, ohms, watts — plus Ohm's law, resistor color codes, and wire ampacity. This hub covers energy itself (joules and derivatives: kWh, BTU, calories, eV, toe) and its real-world applications: cost, food, fuel, and home usage. No overlap in scope.

How do I convert watts to kWh?

Energy (kWh) = power (W) × time (hours) ÷ 1,000. A 100 W bulb running 5 hours uses 100 × 5 ÷ 1,000 = 0.5 kWh. You cannot convert watts directly to kWh without a time period, because watts are power (a rate) and kWh are energy (an amount).

Is this converter accurate, and is my data private?

Conversion factors are fixed published values: SI definitions (joule, eV exact), thermochemical calorie 4.184 J, BTU(IT) 1,055.06 J, IEA toe 41.868 GJ, EPA 33.7 kWh/gallon gasoline equivalent. Fuel and exercise figures are labelled estimates. All calculations run 100% in your browser — no data ever leaves your device.

Energy Unit Converter

1Quick Energy Converter

≡Conversion factors (per unit, in joules)

2Energy Cost Calculator

⚖Appliance comparison (30 days)

3Food Energy: kcal ↔ kJ

🏃Burn it off (MET-based, simplified)

4Battery & Fuel Equivalents

5Mini Home Energy Audit

💡Quick-win saving tips

Worked examples

Example 1 — 10,000 BTU → kWh (air-conditioner rating)

Example 2 — Monthly cost of a 1,200 W air conditioner

Example 3 — A 500 kcal meal in kJ, and running it off

Methodology

Core formulas

Conversion factors & sources

Scope boundaries (anti-cannibal)

Frequently asked questions

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