August 28, 2026
TECH SUPPLY SHED
August 28, 2026
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TECH SUPPLY SHED
5,000 vs 10,000 vs 20,000mAh Power Banks: Which Size Do You Actually Need?
Choosing the right power bank capacity is the single most important decision you'll make when buying a portable charger — get it wrong and you'll either run out of juice halfway through the day or lug around unnecessary bulk. This guide breaks down the real-world difference between 5,000mAh, 10,000mAh, and 20,000mAh power banks so you can pick the one that actually matches your life in NZ.
| Capacity | Best For | Typical Phone Charges | Ideal Use Case |
|---|---|---|---|
| 5,000mAh | Light travellers, commuters | 1-1.5x | Daily top-up, pocket carry |
| 10,000mAh | Most people | 2-3x | Weekend trips, busy days, two devices |
| 20,000mAh | Heavy users, multi-device, travel | 4-6x | Long-haul travel, camping, keeping a tablet alive |
5,000mAh Power Banks: The Pocket-Sized Pick-Me-Up
A 5,000mAh power bank is roughly the size of a credit-card wallet and weighs next to nothing - usually under 130g. That makes it the go-to for commuters, students, and anyone who finds a full-size power bank too bulky to carry every day.
What will a 5,000mAh power bank actually charge?
A modern iPhone or mid-range Android sits between 3,200mAh and 4,500mAh. Factor in the 80-85% charging efficiency typical of lithium-ion cells and you're getting roughly one full charge - sometimes a little more, sometimes a little less depending on your phone. If you're just topping up from 30%, one 5K bank will easily carry you through several days of top-ups.
Who should buy a 5,000mAh power bank?
This size suits commuters who charge once during the day, light smartphone users who don't run intensive apps, and anyone packing carry-on only who wants to avoid airline checked-baggage rules on larger cells. MagSafe-compatible 5K options - like the Mophie Powerstation Plus 5K or Cygnett MagSlim 5K - snap directly to the back of your iPhone so you can charge wirelessly without ever pulling a cable out of your bag.
10,000mAh Power Banks: The Sweet Spot for Most People
The 10,000mAh power bank is the bestselling capacity tier for good reason - it hits the optimal balance between charging capacity, portability, and price. At around 180-220g, it fits comfortably in a jacket pocket or day bag and delivers enough power for the vast majority of real-world use cases.
What will a 10,000mAh power bank actually charge?
Expect two to three full charges for a standard smartphone, or one full charge of a flagship phone (iPhone Pro Max, Samsung Galaxy Ultra) plus a significant top-up. It's also enough to charge two phones simultaneously once, making it ideal for couples or anyone who carries a work and personal device.
Who should buy a 10,000mAh power bank?
The 10K category is the right call for most people: weekend hikers, festival-goers, business travellers on short trips, students who need backup during long days on campus, and anyone who just wants one reliable bank that covers them without having to think about it. The Cygnett Encore 10K features a smart screen showing exact charge percentage - a handy feature when you need to know if there's enough left for one more full charge. The Cygnett ChargePro 10K goes the other direction with a fabric-textured shell and minimal footprint if a clean, understated look matters more than the display.
20,000mAh Power Banks: Maximum Capacity for Maximum Demands
A 20,000mAh power bank is serious kit. These units weigh 350-450g and won't fit in a jeans pocket, but they deliver four to six full smartphone charges and can keep a tablet running for hours. If you're travelling, working remotely off-grid, or supporting multiple family members on a long-haul flight, a 20K bank is the right tool.
What will a 20,000mAh power bank actually charge?
Four to five full charges on a mid-size smartphone, two full charges for a 10-inch tablet, and enough left over to top up a pair of wireless earbuds. Models like the Cygnett ChargePro 20K and Belkin BoostUp Charge 20K support 30W USB-C output, meaning your laptop can draw meaningful charge too - useful for keeping a thin-and-light topped up during a long layover.
Who should buy a 20,000mAh power bank?
Long-haul travellers, outdoor adventurers, anyone who regularly charges more than two devices, and NZ travellers heading to remote destinations where power points aren't guaranteed. Note that most 20,000mAh power banks exceed airline carry-on limits for watt-hours - check your airline's policy before you fly. Most 20K lithium-ion banks sit at 74Wh, which is under the standard 100Wh carry-on limit, but always verify before travel.
How to Choose the Right Power Bank Capacity
Think about your longest day without power access
The right capacity is determined by your worst-case scenario, not your average day. If you commute for 30 minutes each way and work at a desk with USB ports, a 5K covers you easily. If you're ever in a situation where you need your phone for navigation, communication, and photography for 12+ hours straight, a 10K minimum is the smarter choice.
Count your devices, not just your phone
Many people now carry a phone, wireless earbuds, and a smartwatch. A 5K bank might only top up your phone once while also charging earbuds, leaving your watch flat. If you carry multiple devices, add up their total battery capacity to size your power bank correctly. As a rough guide: phone (4,000mAh) + earbuds (500mAh) + watch (300mAh) = 4,800mAh consumed per full cycle, so a 10K bank gives you roughly two complete device top-ups.
Consider the output wattage, not just the capacity
A 20,000mAh bank with only 10W output will charge your phone slowly - slower than if it were plugged into the wall. Look for USB-C PD (Power Delivery) support and at least 18W output for modern smartphones, and 30W if you want meaningful laptop charging. Capacity and output speed are independent specs; check both before you buy.
Check your airline's watt-hour limit if you travel
New Zealand's Civil Aviation Authority and most international airlines follow IATA rules: power banks up to 100Wh are permitted in carry-on bags without airline approval. Power banks between 100Wh and 160Wh require approval. To convert: Wh = mAh x Voltage / 1,000. At 3.7V nominal, a 20,000mAh bank = 74Wh (fine), a 27,000mAh bank = 99.9Wh (borderline), and a 30,000mAh bank = 111Wh (requires approval). Most 20K banks are safe; anything larger, double-check.
Decide between wireless and wired charging
Magnetic wireless power banks - MagSafe-compatible models from Mophie and Cygnett MagSlim - are genuinely useful if you hate cable management. They snap to the back of your iPhone and charge without pulling out a cable. The trade-off is efficiency: wireless charging typically converts 60-70% of stored energy versus 85%+ for wired, so your effective capacity is lower. They're also limited to 5K-15K in most cases, as the weight of a 20K wireless bank becomes impractical to hold on the back of your phone.
FAQ
Is 5,000mAh enough for a day trip in NZ?
For most users, yes. If you're spending a day in Auckland, Wellington, or Queenstown and your phone starts at 100%, a 5,000mAh bank gives you a full recharge if your battery runs to zero - enough for a standard 12-hour day of moderate use. If you're shooting photos heavily or running GPS navigation all day, consider stepping up to 10,000mAh.
Can a 10,000mAh power bank charge a laptop?
Partially. A 10,000mAh bank at 30W USB-C PD output can add 20-40% charge to a thin-and-light laptop (MacBook Air, Dell XPS 13, Surface Pro). It won't fully charge a 15-inch gaming laptop. If laptop charging is a priority, a 20,000mAh bank with 45W+ output is a better investment.
How long does it take to recharge a 20,000mAh power bank?
At 10W input (standard USB-A wall adapter), expect 8-10 hours. With a 30W USB-C PD wall charger - check if your bank supports fast input - you can cut that to 4-5 hours. Always use the fastest-input adapter your power bank supports to avoid leaving it plugged in overnight repeatedly.
Are power banks allowed on NZ domestic flights?
Yes - power banks up to 100Wh in carry-on bags are allowed on Air New Zealand and other NZ domestic carriers. All standard 5K, 10K, and 20K power banks fall well under this threshold. They must be carried in the cabin - never in checked baggage.
What's the difference between mAh and Wh on a power bank?
mAh (milliamp-hours) measures charge storage; Wh (watt-hours) measures energy storage and accounts for voltage. Airlines and regulators use Wh because it's a more accurate measure of stored energy. To convert: multiply mAh by the cell voltage (typically 3.7V) and divide by 1,000. A 10,000mAh bank at 3.7V = 37Wh. Always check the Wh figure printed on the power bank itself for airline compliance.
Top Brands at Tech Supply Shed NZ
Belkin
Belkin's BoostUp Charge range is engineered for reliability - their 20K USB-C model delivers 15W output with a clean LED indicator and no-fuss cable compatibility. A consistent performer for travellers and daily commuters alike.
Cygnett
Cygnett is one of the most comprehensive power bank ranges available in NZ. From the MagSlim magnetic 5K for iPhone users to the ChargePro 20K with fabric-textured shell and USB-C PD output, Cygnett covers every use case and budget level. Their Encore series adds a smart percentage-display screen that removes the guesswork from knowing how much charge remains.
Mophie
Mophie Powerstation power banks are the premium choice for Apple ecosystem users. Their 5K and 10K Powerstation Plus models include a built-in cable and MagSafe-compatible magnetic attachment, making wireless charging genuinely frictionless for iPhone users. Build quality is excellent and the design is compact relative to capacity.
Browse the full power banks range at Tech Supply Shed NZ, or explore related categories including wireless chargers and charging cables to complete your setup.
