Energy Converter

How to use Energy Converter

1. Open Energy Converter in your browser — it loads instantly and works offline once cached.
2. Enter your values in the input fields. Every field is labelled so you know exactly what to type.
3. The result updates automatically as you type — there is no "submit" round-trip to a server.
4. Adjust any input to compare scenarios and see how the outcome changes in real time.
5. Copy or note the result. Nothing you enter is stored or sent anywhere.

Why use Energy Converter?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full unit conversion suite, so related energy tasks are one click away.

What people use Energy Converter for

• Converting between joules, calories, kWh and BTU.
• Comparing energy figures quoted in different units.
• Converting a food energy value between kcal and kJ.

Energy Converter: limits and things worth knowing

• A food 'calorie' is really a kilocalorie: 1 kcal is 4,184 joules. Nutrition labels showing both kcal and kJ use this factor, and the lowercase calorie is a thousand times smaller.
• 1 kWh is 3.6 million joules, which is why electricity is billed in kWh rather than joules.
• Energy and power are different quantities. A watt is a joule per second, so a 100 W device running for an hour uses 0.1 kWh.
• BTU persists in heating and air conditioning; 1 BTU is about 1,055 joules.

Is it private and secure?

Your privacy is built in. Energy Converter runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Why Browser-Based Tools Are Safer for Your Files — Most online converters upload your files to a server. Client-side tools don't. Here's why that difference matters for privacy.