Hey everyone! 👋 Anyone who builds electronics knows the question: “How long will this battery actually last?” Most online battery calculators only divide capacity by current. That gives a number that looks right on paper, but real batteries run out much sooner. Cold weather, aging cells and efficiency losses all shorten the runtime, and projects usually power several components at once, not just one. So we built a calculator that gets closer to real-world results. The first version only calculated runtime from capacity and load. While building it, we added Capacity and Power modes, so you can work backwards from the runtime you need. Then we added a device library with common parts like Arduino boards, sensors, LEDs and motors, plus multi-device totals. Finally, we added advanced settings for temperature, aging, efficiency, series/parallel cells, C-rate and safety margin. It’s 100% free with no signup, for hobbyists and professionals alike. What components should we add to the library next? 🙌

Battery Life Calculator

Runtime, capacity & power for any battery project

Runtime, capacity & power for any battery project