Best power banks to keep your phone alive (2026)
In a power cut, your phone is your lifeline — for news, for 999, and (increasingly) because your landline now needs mains power too. A power bank is the cheapest, simplest way to keep it alive for days, and for most households it's all the backup power you actually need. Here's how to pick one that holds its charge and delivers it fast.
By Tom Rowland · Updated 18 July 2026 · 5 products, price-tracked
Before you buy
Size it to your phone. A modern phone battery is roughly 4,000–5,000mAh, so a 10,000mAh bank gives about two full charges and a 20,000–26,800mAh bank gives four or five — enough to keep a household's phones going through a multi-day outage. Remember the rated capacity isn't all usable: real-world output is typically 60–70% of the label after conversion losses.
Then charging speed and ports. Look at the maximum output in watts and whether it supports your phone's fast-charging standard (USB-C Power Delivery for most modern phones); a higher-wattage bank like the Anker 737 can even top up a laptop. Multiple ports (at least one USB-C plus a USB-A) let you charge a phone and a second device at once — useful for a household.
Two practical points reviews skip. Keep it charged — a power bank left flat for months is no use in an outage, so top it up every few months. And if you want it to charge your phone and recharge itself at the same time (pass-through), check the spec, as not all support it. For grab bags, a compact 10,000mAh model that charges via USB-C is the easiest to keep topped up.
Top pick: Anker 737 Power Bank (PowerCore 24K). A genuinely capable 24,000mAh pack that will recharge phones many times over and fast-charge most laptops via its 140W USB-C port. The clear digital display showing charge left and time remaining is a real plus in an emergency, though it is heavy and priced well above ordinary phone banks.
| Power bank | Capacity | Max output | Ports | Price | |
|---|---|---|---|---|---|
| Anker 737 Power Bank (PowerCore 24K)TOP PICK | 24,000 mAh | 140 W | 2x USB-C, 1x USB-A (3 ports) | £100.00at usual price | Check price → |
| INIU B6 20000mAh Power Bank | 20,000 mAh | 22.5 W | 1x USB-C (in/out), 2x USB-A | £23.00at usual price | Check price → |
| Anker Nano Power Bank 10000mAh | 10,000 mAh | 30 W | Built-in USB-C cable + USB-C + USB-A | £35.00at usual price | Check price → |
| Anker PowerCore 26800 Power Bank | 26,800 mAh | 30 W | 3x USB-A out, 2x micro-USB in (no USB-C) | £55.00at usual price | Check price → |
| Belkin BoostCharge 20K Power Bank | 20,000 mAh | 15 W | 1x USB-C (15W), 2x USB-A (12W); USB-A to USB-C cable in box | £22.00at usual price | Check price → |
ⓘ We may earn a commission when you buy through our links — it never affects what we recommend, and we buy everything we test.
Anker 737 Power Bank (PowerCore 24K)
Who it's for: Keeping a laptop and phones running through a multi-day power cut or off-grid trip.
A genuinely capable 24,000mAh pack that will recharge phones many times over and fast-charge most laptops via its 140W USB-C port. The clear digital display showing charge left and time remaining is a real plus in an emergency, though it is heavy and priced well above ordinary phone banks.
- 140W USB-C output is enough to charge most USB-C laptops, not just phones
- Smart display shows exact percentage remaining and charge time - useful when you're rationing power
- 86.4Wh keeps it under the 100Wh airline limit, and Anker build quality is dependable
- Expensive and heavy (around 630g) - it's a lot of pack to carry
- Overkill if you only ever top up a phone
Don't buy if You just want to keep a phone topped up - a £20-30 10,000mAh bank does that job for a fraction of the price and weight. And remember this charges USB devices only; it won't run mains appliances like a fridge or kettle, which needs a portable power station instead.
INIU B6 20000mAh Power Bank
Who it's for: Keeping phones and tablets topped up during a power cut or a long day away from the mains.
A genuinely good-value 20,000mAh pack that delivers close to its rated capacity, with a clear battery display, a handy pull-out phone stand and an unusually long three-year warranty. For most households wanting a reliable backup for phones and tablets, it is hard to beat at the price.
- High real-world efficiency — independent testing shows it delivers a large share of its rated capacity, unlike many cheap banks
- Three outputs (USB-C plus two USB-A), a readable charge-level display and a built-in phone stand
- Three-year warranty is well above the norm at this price
- 22.5W output is modest — fine for phones and tablets but slow to recharge the bank itself and not enough for most laptops
- At around 340g it is a chunky thing to carry every day
Don't buy if You need to fast-charge or run a laptop, or want the quickest possible recharge — step up to INIU's 65W model (the B62) instead. If you only ever top up a single phone, a lighter 10,000mAh bank will cost less and weigh half as much.
Anker Nano Power Bank 10000mAh
Who it's for: Keeping a phone and small devices topped up during a short power cut or away from the mains.
A compact, well-made power bank from a brand with a strong safety record, and the built-in USB-C cable means there's one less thing to lose from a grab bag. The 10,000mAh capacity is enough for roughly one-and-a-half to two phone charges, so treat it as a sensible everyday-and-short-outage top-up rather than a way to ride out a long blackout.
- Built-in USB-C cable plus separate USB-C and USB-A ports, so you can charge without hunting for a lead
- Genuinely pocket-sized and light, which suits a grab bag or bedside drawer
- 30W output charges a modern phone quickly and can trickle a small tablet
- Trusted brand with a good reputation for battery safety and honest capacity
- 10,000mAh only covers around one-and-a-half to two phone charges, not larger devices for long
- The built-in cable is USB-C only, so older Lightning or micro-USB kit needs the separate ports and your own lead
Don't buy if You want to keep devices running through a multi-day outage or power anything larger than phones and tablets. For that, size up to a higher-capacity bank or a proper portable power station rather than relying on this.
Anker PowerCore 26800 Power Bank
Who it's for: Keeping phones and tablets topped up through a multi-day power cut.
A dependable, high-capacity workhorse that will recharge a typical phone five or six times, making it a sensible anchor for a home power-cut kit. Just note it is an older USB-A design, so it charges phones at moderate speed and takes several hours to refill itself.
- Large 26800mAh capacity charges most phones five to six times before it needs a refill
- Three USB-A ports charge three devices at once, useful for a household
- Anker is a well-established brand with a solid safety and reliability record
- No USB-C and no Power Delivery, so it will not fast-charge modern phones or run a laptop
- Recharges slowly over micro-USB, taking roughly six-plus hours even with both inputs in use
Don't buy if You need to charge a laptop or want quick USB-C recharging of the bank itself, in which case choose the PowerCore 26800 PD 45W or a newer USB-C model instead.
Belkin BoostCharge 20K Power Bank
Who it's for: Keeping phones, tablets and earbuds topped up through a power cut or a long day out.
A dependable, no-drama 20,000mAh bank from a trusted brand that will recharge a typical phone three or four times. Just don't expect fast charging or enough grunt to run a laptop.
- Large 20,000mAh capacity reliably recharges a modern phone three to four times
- Three ports (one USB-C, two USB-A) charge several devices at once, and a charging cable is included
- Belkin's reputation and two-year warranty make it a low-risk buy at around £22
- Modest 15W maximum output is slow by 2026 standards, and that power is shared across ports when charging multiple devices
- No high-wattage USB-C Power Delivery, so it won't meaningfully charge a laptop
Don't buy if You need to fast-charge a laptop or want rapid 45W+ USB-C PD top-ups — look at a higher-output bank instead.
Get price-drop alerts on these
We track every price daily. Tell us which and we'll email you when it drops.
We verify every product's specifications against at least two independent sources, track its UK price and stock on a schedule, and cross-check safety-relevant claims against official guidance. Where we've bought and used a product ourselves we say so on its review; where we haven't, our verdict is a considered spec-and-evidence comparison, not a hands-on test — and commissions never change a ranking either way. Read our full methodology →
Guides that go with this
The free number to save today, what to have ready, food safety, staying warm safely, and the compensation you …
The UK's old copper phone network is being switched off by January 2027. What the digital switchover means, wh…
A calm, sourced look at the 'national blackout' scenario: why it's a low-likelihood risk the grid is engineere…
Common questions
What size power bank do I need for a power cut?
For keeping phones going over a day or two, a 20,000–26,800mAh bank gives around four to five full phone charges. A compact 10,000mAh model (about two charges) is fine for one person or a grab bag. Bear in mind only about 60–70% of the rated capacity is usable.
Is a power bank enough, or do I need a power station?
For phones, a tablet and a torch — the realistic power-cut need — a power bank is enough and far cheaper. You only need a power station if you want to run real appliances, medical equipment or charge many devices repeatedly over a long outage.
Why does my power bank deliver less than its rated capacity?
Conversion and voltage losses mean you typically get about 60–70% of the printed mAh figure as actual charge into your device. So a 20,000mAh bank delivers the equivalent of roughly 13,000–14,000mAh — normal, not a fault.
What charging features should I look for?
A high maximum output in watts, support for your phone's fast-charging standard (usually USB-C Power Delivery), and at least two ports so you can charge more than one device. A higher-wattage bank can also top up a tablet or laptop.
How do I keep a power bank ready for an emergency?
Charge it fully and top it up every couple of months, because power banks slowly self-discharge and a flat one is useless when you need it. Store it somewhere you'll remember, ideally with the right cable attached.
Can a power bank charge my phone and itself at the same time?
Some support 'pass-through' charging, letting them recharge from the mains while charging your phone — but not all do, and it can generate heat. If that matters to you, check the specification before buying.