Wireless Charging Time Calculator
Calculate exactly how long wireless charging will take for your device. Enter battery size, wattage, and efficiency for an instant estimate.
Wireless charging time depends on battery size (mAh), charger wattage (W), and charging efficiency (typically 75-85%). Use our free calculator for your specific device.
How to Calculate Wireless Charging Time
Use our free Wireless Charging Time Calculator to get an instant estimate for your specific device and charger combination.
Simply enter:
- Battery capacity (mAh — found in your device specifications)
- Charger wattage (the rated output of your wireless charger)
- Charging efficiency (typically 75-85% for wireless; default is 80%)
- Charge range (starting and ending battery percentage)
The calculator handles the rest and shows you the estimated time, effective wattage, and a comparison across common charger speeds.
The Wireless Charging Time Formula
For those who want to understand the math:
Step 1: Convert battery capacity to Watt-hours.
Battery capacity (mAh) × nominal voltage (3.7V) / 1000 = Wh
Example: 4000 mAh × 3.7 / 1000 = 14.8 Wh
Step 2: Calculate effective charging power.
Charger wattage × efficiency = effective watts to battery
Example: 15W × 0.80 = 12W effective
Step 3: Calculate charging time.
Battery Wh ÷ effective watts = hours
Example: 14.8 ÷ 12 = 1.23 hours (~1 hour 14 minutes)
Quick Reference: Common Charging Times
| Phone Battery | 5W Charger | 10W Charger | 15W Charger |
| 3000 mAh | ~3.5 hours | ~2 hours | ~1.5 hours |
| 4000 mAh | ~4.5 hours | ~2.5 hours | ~2 hours |
| 5000 mAh | ~6 hours | ~3 hours | ~2.5 hours |
What Affects Wireless Charging Time?
Charger wattage — The primary factor. Doubling wattage roughly halves charge time.
Battery size — Larger batteries take longer. A 5000 mAh battery takes about 25% longer than a 4000 mAh at the same wattage.
Efficiency — Cheap chargers may only be 65-70% efficient, adding 15-20% to estimated times. Premium Qi2 chargers typically hit 80-85%.
Phone activity — Screen on, GPS active, or gaming draws power simultaneously, reducing net charging rate. Add 20-50% to estimates for active use while charging.
Temperature — Heat throttling reduces charging speed. Hot environments add significant time.
Battery level — Charging slows above 80-85% as the battery management system protects against overvoltage. The final 20% takes proportionally longer.
Use the Calculator
Open Wireless Charging CalculatorEnter your specific values for the most accurate estimate.