Estimate battery runtime based on capacity and device power consumption. Supports mAh/Wh conversion. No sign-up required · Data never leaves your device
Zero dependencies · Works offline🔋 Battery Parameters
⚡ Device Power Consumption
📊 Calculation Results
| Metric | Value | Description |
|---|---|---|
| Theoretical runtime | 10.00 hour | Ideal value without losses |
| Actual runtime | 8.50 hour | Adjusted for conversion efficiency |
| Battery energy | 18.50 Wh | Actual stored energy |
| Usable energy | 15.73 Wh | Energy after efficiency loss |
| Average power | 1.85 W | Device average power consumption |
🔁 Charge Count Estimator
📖 What Can the Battery Life Calculator Do?
The battery life calculator estimates theoretical and actual runtime based on battery capacity (mAh), nominal voltage (V), and device power consumption (mA/W). It supports Wh energy conversion, charge count estimation, and discharge rate calculation. Suitable for phones, power banks, IoT devices, drones, and more.
Key Features
- Dual-mode input: Supports both current (mA) and power (W) input modes
- Efficiency calculation: Accounts for voltage conversion efficiency, providing actual runtime (default 85%)
- Wh energy conversion: Automatically calculates the actual stored energy (Wh)
- Charge count estimation: Calculates how many times a power bank can charge a target device
- Discharge rate: Shows C-rate to evaluate battery discharge intensity
- Real-time calculation: Instant results as you type, no need to click
How to Use
- Enter battery parameters: Fill in battery capacity (mAh) and nominal voltage (V). Common lithium battery nominal voltage is 3.7V, some devices use 3.85V.
- Enter device power consumption: Select current (mA) or power (W) mode, enter the average power consumption during operation.
- Set efficiency: Voltage conversion efficiency defaults to 85%, adjustable based on actual conditions (80%-95%).
- View results: Automatically shows theoretical runtime, actual runtime, battery energy (Wh), and discharge rate.
- Charge estimation (optional): Enter target device battery parameters to calculate charge count.
Use Cases
Case 1: Phone Runtime Estimation
Given a phone battery of 5000mAh, 3.87V, standby consumption ~15mA, the estimated standby time is ~278 hours (~11.6 days).
Case 2: Power Bank Charge Count
A 10000mAh/3.7V power bank charging a 4000mAh/3.85V phone at 85% efficiency can charge ~2.3 times, helping plan trips.
Case 3: IoT Device Battery Selection
Sensor average consumption 2mA, needs to run for 6 months (4320 hours), requires at least 8640mAh battery capacity.
Case 4: Drone Flight Time
Drone battery 1500mAh/11.1V, flight consumption 12A, theoretical runtime ~7.5 minutes, ~6 minutes at 80% efficiency.
Extended Knowledge
Battery capacity is typically rated in mAh (milliamp-hours), but mAh is voltage-dependent — batteries with different voltages cannot be directly compared. Wh (watt-hours) = mAh × V / 1000, is an energy unit better suited for cross-voltage comparison. For example, airline regulations limit carry-on batteries to 100Wh. Lithium battery nominal voltage is typically 3.6V-3.87V (single cell), power banks are usually 3.7V. Discharge rate C = actual current / nominal capacity, 1C means full discharge in 1 hour, 2C means 30 minutes. High C-rate discharge accelerates battery aging.
FAQ
How is battery runtime calculated?
Battery runtime = battery capacity (mAh) / device consumption (mA). For example, a 5000mAh battery with 500mA consumption gives ~10 hours. Actual runtime is affected by voltage conversion efficiency, temperature, and other factors.
What's the difference between mAh and Wh?
mAh is a charge unit, Wh is an energy unit. Wh = mAh × voltage (V) / 1000. Wh better reflects actual stored energy since mAh values across different voltages aren't directly comparable.
Why does the calculated result differ from actual runtime?
Actual runtime is affected by voltage conversion efficiency (typically 80-95%), battery aging, ambient temperature, and device usage patterns. This tool provides theoretical values; we recommend estimating actual runtime at 80% efficiency.
How many times can a power bank charge my phone?
Charge count = power bank Wh × conversion efficiency / phone battery Wh. For example, a 10000mAh/3.7V power bank (37Wh) charging a 3000mAh/3.85V phone (~11.55Wh) at 85% efficiency gives ~2.7 charges.
What is the C discharge rate?
C-rate indicates charge/discharge speed. 1C = full discharge in 1 hour. A 2000mAh battery at 1C discharges at 2000mA (2A), at 2C it's 4A. Higher C-rate means more heat generation.