Battery Life Calculator
Free battery life calculator. Estimate how long your device battery will last based on capacity (mAh/Wh) and power consumption (mA/W). Perfect for phones, laptops, IoT devices, and DIY projects.
Real-world batteries are typically 80-90% efficient
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Know Your Battery Runtime
Whether you're designing an IoT device, planning a camping trip, or just curious about your phone's battery, our calculator gives you accurate runtime estimates based on capacity and power draw.
How is Battery Life Calculated?
Battery life depends on two factors: how much energy the battery stores (capacity) and how fast the device uses it (consumption). Capacity is measured in milliamp-hours (mAh) or watt-hours (Wh), while consumption is in milliamps (mA) or watts (W).
Battery Life Formula
Time (hours) = Capacity (mAh) ÷ Current (mA)Why Calculate Battery Life?
Device Design
Choose the right battery size for your project's power requirements.
Trip Planning
Know if your devices will last through a flight, hike, or power outage.
Compare Options
Evaluate different battery and device combinations before purchasing.
How to Use the Battery Life Calculator
Common Applications
Smartphone Usage
Estimate screen-on time based on your phone's battery and usage patterns.
Power Banks
Calculate how many charges you'll get from your portable charger.
IoT Projects
Size batteries for Arduino, ESP32, or Raspberry Pi projects.
Solar Systems
Design off-grid power systems with appropriate battery banks.
Frequently Asked Questions
Real-world factors include: discharge efficiency (80-90%), voltage drop as battery depletes, temperature effects, and variable power consumption. Use 80-85% efficiency for realistic estimates.