Pick a power bank by matching your device’s wattage, capacity in Wh, ports, and safety marks, then weigh size, price, and any travel rules.
Shopping for a portable charger looks simple—until specs start flying. Milliamp hours, watts, ports, and fast-charge logos all change how well a pack serves your phone, tablet, laptop, or camera. This guide keeps choices clear so you buy once and stay powered anywhere.
Power Bank Basics You Need First
Before comparing models, lock in a few terms found on every spec sheet. You’ll make faster choices and avoid paying for features you never use.
Capacity And Why Watt-Hours Matter
Battery size is often printed in milliamp hours (mAh). Real runtime tracks watt-hours (Wh), which accounts for voltage. Convert with: Wh = (mAh × 3.7) ÷ 1000. Packs around 10,000 mAh hold about 37 Wh; 20,000 mAh sits near 74 Wh. Expect some loss during conversion and cables, so usable energy is lower than the label.
Output Power And Fast Charging
Output is expressed in watts (W). Phones tend to sip 18–30 W with fast charge. Many tablets sit near 20–30 W. Slim notebooks may need 45–65 W, while bigger laptops often want 65–100 W. Buy for your highest-draw device so the pack never rate-limits your day.
Ports, Cables, And Standards
USB-C is the modern default. A good pack should offer USB-C PD (Power Delivery) for two-way fast charge and, ideally, PPS for Samsung phones. If you carry older accessories, one USB-A port can help, but treat it as a backup. Keep a short, certified USB-C cable in the pouch; the cable can bottleneck charge speed.
Quick Specs Decoder (Save This)
Use this table to translate the terms you’ll see while browsing. It keeps your eye on what affects real-world use.
| Spec | What It Means | What To Look For |
|---|---|---|
| Capacity (mAh / Wh) | Size of stored energy | 10,000 mAh for phones; 20,000–27,000 mAh for tablets; 30,000+ for laptops (within Wh rules) |
| Max Output (W) | Peak charging rate | 18–30 W for phones, 45–65 W for most laptops, 100 W for demanding notebooks |
| USB-C PD / PPS | Fast-charge standards | USB-C with PD 3.x; PPS if you use recent Samsung or similar |
| Ports | Ways to connect gear | At least one USB-C with input/output; extra USB-A if needed |
| Recharge Input (W) | How fast the pack refills | USB-C input 18–60 W shortens downtime |
| Safety Marks | Independent testing | UL 2056 listing, IEC 62133 for cells, full protections |
| Size & Weight | Pocket vs. bag carry | Under 250 g for pocket carry; 400–700 g for laptop-class packs |
| Features | Extras that matter | Pass-through, low-power mode for earbuds, clear LED or display |
Find Your Wattage Need
Match the pack’s advertised wattage to the charger rating your device expects. You’ll find this on the original power brick or on the maker’s site. If your ultrabook charger says 65 W, pick a pack that can deliver 65 W on a single USB-C port, not just a shared total across two ports.
Phone And Small Tablet
Most recent phones fast-charge at 18–30 W. A compact 10,000–12,000 mAh pack with 20–30 W USB-C PD will handle a full day or two. Heavy video or GPS use? Step to 20,000 mAh for headroom without much bulk.
Large Tablet
Pick 20,000–27,000 mAh and 30 W or higher. If the tablet supports PPS, match a pack that lists PPS in the spec.
Laptop
Check the adapter rating. Slim models often need 45–65 W. Workstations may expect 90–100 W. Choose a pack that meets the single-port wattage and has enough capacity to add real runtime—usually 20,000–30,000 mAh.
Travel Rules And Safety Signals
Portable batteries follow baggage rules. Spare lithium packs belong in cabin bags, with terminals protected from shorting. Airlines often set limits in watt-hours: up to 100 Wh is usually fine; 100–160 Wh may require airline approval; above that isn’t allowed for passengers.
Look for independent testing on the spec sheet or packaging. Wording like “Tested to UL 2056” indicates a safety review of the finished pack. IEC 62133 covers cell safety. Avoid crushed or swollen packs and recycle damaged units.
Need the technical reference? The USB Implementers Forum publishes the USB Power Delivery spec that enables safe high-wattage charging over USB-C. For flyers, IATA’s guidance explains watt-hour limits and carry-on rules. Links are below inside the article.
How To Choose The Right Power Bank (Quick Method)
Use this six-step filter to trim the list, then compare two or three finalists.
1) List Your Devices And Chargers
Write down each device and the wattage of its wall charger. If any item needs 65 W, that sets your minimum output. Mark devices you charge at the same time.
2) Pick A Capacity Range
Use the Wh math. Phones: 10,000–12,000 mAh (about 37–45 Wh). Tablets: 20,000–27,000 mAh (around 74–100 Wh). Laptops: 20,000–30,000 mAh (74–111 Wh). If you fly often, stay under 100 Wh.
3) Match The Port Standard
Choose USB-C with PD 3.x on at least one port; PPS if your phone supports it. If you carry legacy gear, one USB-A port is handy.
4) Check Refill Speed
A pack that accepts 45–60 W via USB-C refills in hours, not overnight, when paired with a capable wall charger.
5) Confirm Safety And Build
Scan for over-temperature, short-circuit, and overcharge protection. Look for UL 2056 listing and IEC 62133 for the cells.
6) Weigh Size, Weight, And Price
Everyday carry packs live in a pocket; laptop packs live in a backpack. Balance grams against your longest day away from outlets. Skip features you never use.
Real-World Checks Before You Buy
Spec sheets don’t tell the whole story. These quick checks protect your money and your devices.
Honest Capacity Claims
Respectable makers show both mAh and Wh. If only mAh appears with no Wh, be cautious.
Single-Port Wattage
Total output of “65 W” can be split across ports. You want the rating for one USB-C port while the others sit idle.
Cable Quality
Not all USB-C cables carry 5A or support e-markers for high wattage. Pair the pack with a cable rated for the job.
Displays And Buttons
A clear readout saves guesswork. A percentage display beats four dots when you plan long shoots or travel legs. A low-power mode helps with earbuds.
Capacity Planner: Pick The Right Size
Use your heaviest day as the baseline, then find the closest match below.
| Use Case | Recommended Capacity | Why It Fits |
|---|---|---|
| City Errands + Calls | 10,000–12,000 mAh | One to two phone refills without bulk |
| Travel Day With Tablet | 20,000–27,000 mAh | Phone + tablet top-ups, still cabin-friendly |
| Work Trip With Laptop | 25,000–30,000 mAh | Meaningful laptop runtime plus phone refills |
| Camera Shoots | 20,000–30,000 mAh | Fast USB-C PD for cameras and lights |
| Group Carry | 30,000 mAh+ | Multiple phones; confirm Wh limits if flying |
Wattage Ranges At A Glance
Phones often aim for 18–30 W on PD/PPS. Large tablets sit near 20–45 W. Ultrabooks sit at 45–65 W, while creator and gaming rigs can pull 90–100 W over USB-C. If a pack claims 140 W, check the single-port rating.
Travel Notes You’ll Be Glad You Read
If you fly, keep spare batteries in carry-on bags and protect terminals. Many carriers cap packs at 100 Wh without approval; 100–160 Wh may need a green light. Rules can change by airline.
For standards and rules from the source, see the USB-IF’s USB Power Delivery documentation and IATA’s lithium battery guidance. These pages outline charge profiles, watt-hour limits, and baggage placement.
Care, Charging Habits, And Lifespan
Keep packs dry and shaded. Avoid leaving one in a hot car. Partial cycles are fine. If storage runs long, leave the pack near half charge and cycle it monthly.
Use wall chargers that match the refill input rating. If your pack allows 45–60 W input, a matching PD charger shortens downtime. Clean ports with a soft brush.
Troubleshooting Common Head-Scratchers
My Phone Charges Slowly
Check the cable first. Then confirm you’re on the USB-C port with PD or PPS. If the pack shares wattage across ports, unplug extras.
The Pack Turns Off With Earbuds
Many packs auto-sleep at low currents. Trigger low-power mode if available, or use a short cable.
The Pack Feels Hot
Warm during fast charge is normal. Hot to the touch is not. Stop use and let it cool. If it swells or shows damage, recycle it.
Checklist Before You Click Buy
- Capacity in Wh matches your travel and runtime needs
- Single-port USB-C output meets your highest charger rating
- USB-C PD on board; PPS if your phone supports it
- Refill input wattage high enough for quick top-ups
- Safety marks: UL 2056, IEC 62133; full protections listed
- Clear display or LEDs, low-power mode, and solid build
- Size and weight suit pocket or bag carry
- Reasonable warranty and responsive seller
Bottom Line Recommendation
Match wattage to your hungriest device, pick capacity by day length and travel plans, insist on USB-C PD with a quality cable, and choose a pack with proven safety marks. Do that, and your phone, tablet, and laptop stay charged without drama at home, on campus, or at 35,000 feet.