Power banks are sold on one big number, milliamp-hours, but the number that decides whether your laptop charges is watts. Plenty of 20,000mAh banks will not charge a laptop at all, while a smaller one with a 65W port will. Here is how to read the labels so you buy once.
mAh: how much energy is in the tank
Milliamp-hours describe capacity at the battery's internal voltage, usually 3.7V. Real-world rules of thumb after conversion losses:
- 10,000mAh: roughly two full charges of a modern phone. Fits in a jacket pocket.
- 20,000mAh: four phone charges, or one 13-inch laptop charge plus a phone.
- 25,000mAh: about the largest size still allowed in carry-on luggage; one to one-and-a-half laptop charges.
Expect to get about 60 to 70 percent of the rated mAh into your device; the rest is lost converting voltage and as heat. That is normal for every brand.
Watts: how fast it can deliver that energy
Watts are what matter for laptops. USB-C Power Delivery (PD) negotiates a voltage and current between the bank and the device. If the bank cannot supply roughly what your laptop charger supplies, the laptop either charges very slowly, holds steady while in use, or refuses the connection altogether.
Match the bank to your laptop charger
- Phones and tablets: 20 to 30W. The 10,000mAh Anker at 30W is ideal.
- MacBook Air, thin Windows ultrabooks, iPad Pro: 30 to 65W chargers. A 45W bank will charge them slowly while idle; 65W like the INIU laptop bank charges at near full speed.
- 14- to 16-inch work and creator laptops: 65 to 100W chargers. Pick a 100W-rated bank such as the INIU 25,000mAh.
- Gaming laptops with barrel chargers: most cannot charge over USB-C at all, or only trickle. A power bank will not run them at full performance.
Total output vs per-port output
Read the fine print. "165W total" on the Anker laptop bank means three ports sharing that budget; its listing states each USB-C port can do 100W, so a laptop and phone charge together at full speed. Cheaper multi-port banks often drop to 15 to 20W per port as soon as a second device is plugged in.
The 100Wh airline rule
Transport Canada and airlines allow power banks in carry-on only (never checked), and generally up to 100Wh without approval. Convert with Wh = mAh x 3.7 / 1000: a 25,000mAh bank is about 92.5Wh, which is why 25,000mAh is the largest "travel" size you will see. The Anker 25,000mAh listing explicitly notes it complies with the airline limit.
Six power banks compared
| Product | Key specs (from the listing) | Price (CAD) | Who it's for |
|---|---|---|---|
|
Anker Power Bank, 10,000mAh, 30W USB-C Portable Charger rated 4.5/5 by 23,400 buyers |
10,000mAh, 30W USB-C output | $69.99 | Phone users who want a fast, pocketable top-up. |
|
INIU 20000mAh Power Bank, 45W Fast Charging Travel Portable Charger rated 4.4/5 by 29,000 buyers |
20,000mAh, 45W fast charging | $70.99 | Weekend trips: two to four phone charges and emergency laptop top-ups. |
|
INIU Laptop Power Bank, 20000mAh, 65W Fast Charging rated 4.3/5 by 3,900 buyers |
20,000mAh, 65W fast charging, laptop-rated | $90.99 | Ultrabook and tablet owners who need a real laptop charge on the go. |
|
INIU 25000mAh Laptop Power Bank, 100W Fast Charging rated 4.4/5 by 5,100 buyers |
25,000mAh, 100W fast charging, laptop-rated | $121.99 | Owners of 14- to 16-inch laptops whose chargers are rated 65 to 100W. |
|
UGREEN 145W Laptop Power Bank 25000mAh, 3-Port USB-C Portable Charger rated 4.4/5 by 8,000 buyers |
25,000mAh, 145W, 3-port USB-C | $195.99 | Charging a laptop and a phone at the same time without either slowing down. |
|
Anker Laptop Power Bank, 25,000mAh, 3-Port, 165W Total Output rated 4.4/5 by 12,600 buyers |
25,000mAh, three 100W USB-C ports, 165W total; retractable built-in cable | $225.99 | Power users with a laptop, tablet and phone who travel light but charge heavy. |
Who each power bank is for
- Anker Power Bank, 10,000mAh, 30W USB-C Portable Charger — Phone users who want a fast, pocketable top-up.
- INIU 20000mAh Power Bank, 45W Fast Charging Travel Portable Charger — Weekend trips: two to four phone charges and emergency laptop top-ups.
- INIU Laptop Power Bank, 20000mAh, 65W Fast Charging — Ultrabook and tablet owners who need a real laptop charge on the go.
- INIU 25000mAh Laptop Power Bank, 100W Fast Charging — Owners of 14- to 16-inch laptops whose chargers are rated 65 to 100W.
- UGREEN 145W Laptop Power Bank 25000mAh, 3-Port USB-C Portable Charger — Charging a laptop and a phone at the same time without either slowing down.
- Anker Laptop Power Bank, 25,000mAh, 3-Port, 165W Total Output — Power users with a laptop, tablet and phone who travel light but charge heavy.
Buying checklist
- Find your laptop charger's wattage (printed on the brick) and buy a bank with a single USB-C port rated at or above it.
- For phones only, 30W is already more than most phones accept.
- Check whether the headline wattage is per port or total.
- Flying? Stay at or under 100Wh (about 27,000mAh); carry-on only.
- Built-in cables save you from a forgotten cable but are one more part to wear out; the Anker uses a retractable one rated for 20,000 retractions.
- A digital percentage display is more useful than four LEDs on a large bank.
- Recharge time matters on big banks: look for fast input (the Anker listing claims 30% in 22 minutes).
FAQs
Why does my 20,000mAh bank only charge my phone three times?
Conversion from 3.7V cells to 5V or higher USB output loses 25 to 40 percent. Three to four charges from 20,000mAh is normal.
Can a power bank charge a MacBook Pro?
Yes, if its USB-C port delivers enough watts. A 16-inch MacBook Pro ships with a 140W charger; a 100W bank will charge it, just more slowly under heavy load.
Can I charge the bank and my phone at the same time?
Many banks support pass-through charging, but not all, and it generates heat. Check the listing; when in doubt, charge the bank first.
Is it safe to leave a power bank in a hot or freezing car?
No. Lithium cells degrade in heat and will not charge below freezing. Keep it in your bag, not the glovebox, especially in a Canadian winter.
Does a bigger bank take forever to recharge?
It can. A 25,000mAh bank with slow input can take all night; models that advertise fast recharging and support 45W or more on the input port refill in two to three hours.
Ready to upgrade?
Browse the full Phone Chargers & Power Banks collection at Nova Toronto Electronics. We ship Canada-wide from Milton, Ontario: flat $7.95 shipping, free on orders over $79, and every order is covered by our 30-day return policy. Prices are in Canadian dollars before HST, so what you see is what a Canadian pays — no surprise duties or currency conversion.