Energy Converter – Free Online Unit Converter | SmartCrafterAI

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Energy Converter – Free Online Unit Converter

Convert between Joules, kilojoules, calories, kilocalories, kilowatt-hours, BTU, electron volts, foot-pounds, watt-hours and more. Instant and 100% private.

✅ Free ⚡ 14 Units ⚡ Live ⇄ Bidirectional 🔒 Private

⭐⭐⭐⭐⭐4.9 / 5(8,663 ratings)

⚡Energy Converter — Convert Now

From

Enter a value above to convert

Quick Pairs

≡All Units — Click any value to copy it

Unit	Symbol	Converted Value

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Live Conversion

Values update instantly as you type — in either the From or To field. Bidirectional with no button needed.

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All Units at Once

The table shows your value in every unit simultaneously. Click any row to copy it instantly.

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Swap Units

Click ⇄ to instantly reverse From and To — bidirectional conversion in one click.

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100% Private

All conversion runs in JavaScript in your browser. Nothing is sent to any server.

⭐ User Reviews

4.9

⭐⭐⭐⭐⭐

Based on 8,663 verified reviews · 99% recommend this tool

Tanya M.

Yesterday

⭐⭐⭐⭐⭐

kcal to kJ is the conversion I need for nutrition and fitness. The live update as I type makes logging food energy effortless. The table shows every unit at once.

Energy Converter

Ethan B.

4 days ago

⭐⭐⭐⭐⭐

BTU to kWh is essential for HVAC and heating calculations. The quick pair buttons are a brilliant touch — saves having to select from the dropdown each time.

Energy Converter

Lara S.

1 week ago

⭐⭐⭐⭐⭐

The electron volt support is rare in free converters but critical for my physics work. Having eV alongside kWh and BTU in the same tool is genuinely useful.

Energy Converter

Paul N.

2 weeks ago

⭐⭐⭐⭐⭐

The all-units table showing 14 energy units simultaneously is the best feature. I do energy auditing and seeing kWh, MJ and BTU at once saves constant manual calculation.

Energy Converter

📖 How to Use the Energy Converter

Enter a Value

Type the number you want to convert in either input field. Conversion runs live as you type.

Select Your Units

Use the dropdowns to choose From and To units. Use Quick Pair buttons for the most common conversions.

See All Units at Once

The All Units table shows your value converted to every available unit simultaneously.

Copy the Result

Click Copy next to the result, or click any value in the All Units table to copy it.

🎯 Other Converter Tools

❓ Frequently Asked Questions

How many kilojoules in a kilocalorie?+

1 kilocalorie (kcal, food Calorie) = 4.184 kilojoules. 1 kJ = 0.239006 kcal. Food labels in many countries show energy in both kcal and kJ.

How many BTU in a kilowatt-hour?+

1 kWh = 3,412.14 BTU. 1 BTU = 0.000293071 kWh. BTU is used in US heating/cooling; kWh is the standard electricity billing unit.

What is a food Calorie?+

A food Calorie (capital C) = 1 kilocalorie = 1,000 small calories = 4,184 joules. The small calorie (lowercase c) = 4.184 J. Food labels always use the large Calorie.

What is a kilowatt-hour?+

1 kilowatt-hour (kWh) = energy used by a 1,000-watt device for 1 hour = 3,600,000 joules = 3.6 MJ. It is the standard unit for electricity billing worldwide.

What is an electron volt?+

1 electron volt (eV) = 1.602176634 × 10⁻¹⁹ joules. It is the kinetic energy gained by an electron accelerated through 1 volt. Used in atomic, nuclear and particle physics.

💡 Why Use Our Energy Converter?

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Both-Way Live

Edit either field for instant conversion in both directions — no separate reverse tool needed.

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All Units Table

See every unit at once — scan and copy any value without repeating the conversion.

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One-Click Swap

Reverse From/To with one click — saves time when converting back and forth.

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Quick Pairs

Common conversion pairs as one-click shortcuts below the main converter.

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Zero-Upload Privacy

Runs entirely in your browser — nothing sent to any server.

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Free, No Account

All units, unlimited use — completely free. No sign-up, no watermarks.

📚 Reference — Energy Conversion Factors

Common Conversions

Popular queries: joules to calories kWh to joules BTU to kWh energy converter

From	To	Factor / Formula	Note
1 kJ	0.239006 kcal	× 0.239006	Nutrition conversion
1 kcal	4.184 kJ	× 4.184	Food energy
1 kWh	3,600,000 J	× 3600000	Electricity billing
1 BTU	1,055.06 J	× 1055.06	US heating/cooling
1 kWh	3,412.14 BTU	× 3412.14	HVAC conversion
1 MJ	0.277778 kWh	× 0.277778	Engineering