What Size Power Bank Do I Need? (Simple Guide for 2026)

Choosing a power bank comes down to one thing: matching capacity to your use case. This guide helps you pick the right size fast,
without guessing.

If you’re buying mainly for flights, check power bank rules for Ryanair and Aer Lingus
before choosing a larger capacity.

Quick answer

• Everyday choice: 10,000mAh
• Heavy use or travel days: 20,000mAh
• Multi-day and multiple devices: 30,000mAh to 50,000mAh
• Emergency kit / maximum backup: 80,000mAh to 120,000mAh

Jump straight to sizes:
5,000mAh,
10,000mAh,
20,000mAh,
30,000mAh,
50,000mAh,
120,000mAh.

What does mAh mean in real life?

mAh is the size of the power bank’s battery. You won’t get 100% of that into your phone due to normal conversion losses.
In real use, expect roughly 60% to 75% of the advertised capacity as usable charge.

If you want a more exact breakdown, see how many times a power bank can charge your phone.

Pick the right size by use case

5,000mAh

Best for: pocket backup, quick top-ups, MagSafe convenience.

Real-world expectation: one rescue charge (often partial to near-full depending on your phone).

Shop:
5,000mAh power banks |
MagSafe power banks

10,000mAh

Best for: everyday use, work, college, general carry in a bag.

Real-world expectation: usually 1 to 2 solid phone charges.

Recommended size for most people: yes.

Shop:
10,000mAh power banks

20,000mAh

Best for: heavy phone users, hotspot, maps, long shifts, travel days, sharing with someone.

Real-world expectation: usually 2 to 3 phone charges.

Shop:
20,000mAh power banks

30,000mAh to 50,000mAh

Best for: multi-day use, festivals, camping, road trips, charging multiple devices.

Real-world expectation: several phone charges over days, plus earbuds and other small devices.

Shop:
30,000mAh power banks |
50,000mAh power banks

120,000mAh

Best for: emergency kits, long trips, group charging, keeping power in the car.

Real-world expectation: lots of charges across multiple devices, but these units are heavy.

Shop:
120,000mAh power bank

Cheat sheet

Common mistakes (quick fixes)

• Buying too small: if you use hotspot or travel, 10,000mAh can feel tight. Go 20,000mAh.
• Buying too big for daily carry: 50,000mAh is great, but not pocket-friendly. Keep it for bag/car use.
• Ignoring charging speed: if it feels slow, it may be the cable or the power bank input/output limits.

If charging feels unusually slow, see why power banks charge slowly and how to fix it.

My recommendation

If you want the safest choice, buy 10,000mAh.
If you’re heavy-use or travelling, buy 20,000mAh.
If you want multi-day independence, buy 50,000mAh or higher.