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 Calder · Updated 20 September 2026 · 5 products, all 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) | — | Check price → |
| INIU B5 20000mAh Power Bank | 20,000 mAh | 22.5 W | 1x USB-C (in/out), 2x USB-A | £22.41as of 20 Sep 2026, 12:29 BST · DetailsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product. | Check price → |
| Anker Nano Power Bank 10000mAh | 10,000 mAh | 30 W | Built-in USB-C cable + USB-C + USB-A | £39.99as of 20 Sep 2026, 12:29 BST · DetailsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product. | Check price → |
| Anker Power Bank 20K (87W, Built-In USB-C Cable) | 20,000 mAh | 87 W | Built-in USB-C cable, USB-C port and USB-A (87W total); recharges over USB-C | £39.98as of 20 Sep 2026, 12:29 BST · DetailsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product. | 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 | £21.99as of 20 Sep 2026, 12:29 BST · DetailsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product. | Check price → |
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Anker 737 Power Bank (PowerCore 24K)
4.5Who 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 B5 20000mAh Power Bank
4.5Who 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, USB-C in and out plus two USB-A outputs, 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 in and out, plus two USB-A) and a readable charge-level display
- 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.
as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Anker Nano Power Bank 10000mAh
4.3Who 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.
as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Anker Power Bank 20K (87W, Built-In USB-C Cable)
4.0Who it's for: Keeping phones and tablets topped up through a multi-day power cut.
A dependable mid-capacity bank that will recharge a typical phone three to four times, making it a sensible anchor for a home power-cut kit. USB-C Power Delivery means modern phones charge quickly and the bank itself refills far faster than the old micro-USB designs.
- 20,000mAh capacity charges most phones three to four times before it needs a refill
- Built-in USB-C cable plus a USB-C port and USB-A charge three devices at once, useful for a household
- Anker is a well-established brand with a solid safety and reliability record
- Lower capacity than the old PowerCore 26800 it replaces, so fewer charges per fill
- 87W is shared across the ports, so charging several devices at once slows each of them
Don't buy if You need to run a laptop or want the most charges per fill, in which case step up to Anker's 25K 165W laptop bank instead.
as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Belkin BoostCharge 20K Power Bank
3.8Who 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
- 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.
as of 20 Sep 2026, 12:29 BST · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.The Power Cut Action Card
One page for the kitchen drawer: what to do first, what to have ready, how long food keeps, and how to stay warm without risking carbon monoxide. Free, no catch.
Download it straight away. We'll also send the occasional briefing when something genuinely matters — severe weather, live incidents, real price drops. Nothing else.
We verify every product's specifications against at least two independent sources, re-check its UK price and stock on a schedule where we can track it automatically, 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 →
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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.