Energy Unit Converter
Effortlessly switch between any energy units. Our tool provides instant and accurate conversions for your needs.
Fast, Free, Private Energy Unit Converter (Offline)
Convert energy units instantly J, kJ, cal, kcal, Wh, kWh, eV, BTU, therm, and ft⋅lbf. 100% client side, lifetime free, unlimited use. No uploads, no sign ups, truly private.
Top, fast, best-in-class, and unlimited. Your information is 100% confidential and secure.
Why people love this energy converter
Offline & secure
Runs entirely in your browser. Your values never leave your device.
Unlimited & free forever
No accounts, no limits convert as much as you want.
Fast & simple
Pick units, type a value, get results instantly with clear precision.
Works everywhere
Modern browsers on Windows, Mac, Linux, and mobile devices.
No data collected
100% client-side processing keeps your data private.
Accurate results
Reliable conversion factors with smart rounding for readability.
Popular uses worldwide
Physics & engineering
Convert J↔kJ, J↔eV for experiments, simulations, and reports.
Electrical & solar
Wh/kWh calculations for batteries, panels, and consumption.
HVAC & energy audits
BTU, therm, and kWh conversions for heating/cooling loads.
Nutrition & fitness
cal/kcal to J for diet tracking and metabolic studies.
Mechanical systems
ft⋅lbf conversions for torque and work calculations.
Education
Learn energy units with clear, instant conversions.
How to convert energy units
- Select your “From” unit (e.g., joule).
- Enter a value (e.g., 5000).
- Select your “To” unit (e.g., kilowatt-hour).
- See instant results and the 1 unit summary below.
- Use “Reset” to start again.
Tip: Edit either side both fields update intelligently.
Supported units
Best practices
- Confirm whether you need energy (Wh/kWh) vs power (W/kW).
- Be consistent with calories: kcal for nutrition; cal for physics.
- Round only at the end if you’ll do further calculations.
- Keep original values for auditing and records.
Frequently Asked Questions
Is it private and secure?
Yes. Everything runs locally in your browser no uploads, no tracking, no servers.
Is it free and unlimited?
Yes. Lifetime free, unlimited conversions, and no sign ups.
Which units are supported?
J, kJ, cal, kcal, Wh, kWh, eV, BTU, therm, and ft⋅lbf.
Does it work offline?
Yes. Your browser caches the app after the first visit.
How accurate are results?
We use precise conversion constants with smart rounding.
What’s kW vs kWh?
kW is power (rate). kWh is energy (power × time). This tool converts energy units.
Global availability (GEO)
Built for users worldwide: USA, UK, Canada, Australia, India, EU (Germany, France, Spain, Italy, Netherlands), Middle East (UAE, Saudi Arabia), Asia (Singapore, Malaysia, Philippines, Indonesia, Japan, South Korea), Africa (Nigeria, South Africa, Egypt), and Latin America (Brazil, Mexico, Argentina).
Also searched as: energy unit converter, convert joule to kilowatt hour, J to kWh, kWh to J, calorie to joule, kcal to kJ, BTU to kWh, eV to J, therm to kWh, foot pound to joule.
Multilingual: convertidor de energía (ES), convertisseur d’énergie (FR), Energieeinheiten umrechnen (DE), convertitore di energia (IT), conversor de energia (PT), конвертер энергии (RU), エネルギー換算 (JA), 能量换算 (ZH), 에너지 단위 변환기 (KO), enerji birimi dönüştürücü (TR), przelicznik energii (PL), energie-eenheden omrekenen (NL), chuyển đổi năng lượng (VI), konverter energi (ID), ตัวแปลงหน่วยพลังงาน (TH), محول وحدات الطاقة (AR), ऊर्जा इकाई परिवर्तक (HI).
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