Reverse Charging Calculator – Phone to Phone Battery Transfer
Calculate battery transfer rates, total transfer time, and remaining charge levels during wireless reverse charging between smartphones with our free reverse charging calculator. This battery sharing calculator helps you understand how much charge you can transfer from your phone to another device, accounting for efficiency losses inherent in wireless reverse charging technology. Plan your phone-to-phone charging intelligently.
Reverse Charging Calculator
Calculate battery transfer between devices
Reverse Charging Calculator Features
- Calculates how much battery is transferred from donor device to receiver device
- Accounts for reverse wireless charging efficiency percentage
- Shows remaining battery in the donor device after transfer
- Calculates estimated time required to complete the reverse charging process
- Displays the maximum transferable mAh from the donor phone
- Useful for planning emergency charging between devices
How to Use Reverse Charging Calculator
- Enter the donor phone’s battery capacity in mAh (e.g., 5000) in the “Donor Battery” field
- Enter the amount of charge needed by the receiver device in mAh (e.g., 1000) in the “Receiver Needs” field
- Enter the reverse charging efficiency percentage (e.g., 70) in the “Efficiency” field
- Enter the reverse charging speed in watts (e.g., 5) in the “Charging Speed” field
- Click the Calculate button
- View the donor’s remaining battery, time to charge, and transferable mAh in the results
- Click Reset to calculate a different scenario
Frequently Asked Questions
Reverse wireless charging (also called reverse power share) allows a smartphone to wirelessly charge another device — like earbuds, smartwatches, or another phone — using its own battery as the power source.
Wireless reverse charging is typically 30–50% efficient due to coil alignment, heat generation, and energy conversion losses. This means transferring 1000mAh to another device may drain 2000–3000mAh from the host phone.
Samsung Galaxy S/Note/Z series, Huawei Mate/P series, Google Pixel 7/8 series, and OPPO/OnePlus flagship phones support reverse wireless charging. Check your phone’s official specifications to confirm.
Always keep at least 30–40% battery on the host phone to avoid putting it in a low-charge state. Most phones also automatically stop reverse charging when host battery drops below 20%.
Yes, wired OTG (USB On-The-Go) charging is significantly more efficient (85–90%) compared to wireless reverse charging (30–50%). However, wireless offers convenience and doesn’t require cables.
Most phones support reverse charging at 5–10W, which is significantly slower than regular fast charging. Charging speed depends on both the host phone’s output and the receiving device’s supported input.
Occasional reverse charging won’t cause significant harm. However, frequent use as the primary charging method for accessories can accelerate battery wear on the host phone over time.
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