How to Work Out How Many Times a Power Bank Can Charge Your Phone
A quick, no-nonsense guide from PowerBanks.ie ☘️ — learn how to estimate your phone’s charge count, and try our free calculator to skip the maths.
🔢 The Simple Formula
Ever looked at a 20,000 mAh or 50,000 mAh power bank and wondered how many charges you’ll actually get? Here’s the short answer — you only need two numbers: your power bank’s capacity and your phone’s battery size.
(Power Bank Capacity × 0.85) ÷ Phone Battery Size = Estimated Full Charges
That 0.85 allows for the usual energy loss during charging. So, if you’re using a 20,000 mAh power bank on a phone with a 3,000 mAh battery:
(20,000 × 0.85) ÷ 3,000 = about 5 ½ charges
Grand for a weekend away or a few days camping without a socket in sight.
⚡ Wired vs Wireless Charging
Wired charging is more efficient — around 85–90%. Wireless drops closer to 70–75% because of heat and alignment loss. So, if you’re using MagSafe or Qi pads, knock off roughly one full charge from your estimate.
🧮 Don’t Fancy Doing the Maths?
We’ve already crunched the numbers for you — check our
It lists real-world charge counts for dozens of iPhones, Samsungs, Pixels and more
🎒 Choosing the Right Size
A 10,000 mAh is perfect for daily use or short trips.
20,000 mAh suits weekends or heavy phone users.
And if you’re camping or travelling off-grid, that 50,000 mAh beast will keep everything — phone, earbuds, camera, even torches — running for days.
💡 Quick Tip
Look for USB-C fast charging, built-in cables, or an emergency solar panel — features that make life easier outdoors.
☘️ PowerBanks.ie – Reliable power for every Irish adventure.
You’ve explained this better than anyone else I’ve read.