Can you charge a MacBook Air 15″ (M4) with a Steam Deck 45W?
Worked out from the manufacturers’ specifications. Have a different charger? Pick it below the answer.
It charges at normal speed. Fast charging needs 70 W or more.
Estimated from the manufacturer’s stated fast-charge time, with the device idle.
Try another charger
How long to 50% with each charger
Shorter bar is faster. The highlighted row is the charger on this page.
Want it faster?
Full speed needs 70 W or more. These chargers get there:
MacBook Air 15″ (M4) charging specs
- Fast charging needs
- 70 W
- Max input (approx.)
- 70 W
- In the box
- 35W Dual
- Battery
- 66.5 Wh
- Steam Deck 45W
- 45 W · USB-C
Sources: Apple: MacBook Air (15-inch, M4, 2025) tech specs · Apple: Fast charge your MacBook Air or MacBook Pro · Steam Deck tech specs. Checked 2026-10-17.
Quick answers
Is it safe to charge the MacBook Air 15″ (M4) with the Steam Deck 45W?
Yes. USB Power Delivery negotiates power, so the MacBook Air 15″ (M4) only takes what it can handle and the charger only gives what it can supply. A weaker charger is slower, not dangerous.
How many watts does the MacBook Air 15″ (M4) need for fast charging?
70 W or more. Fast-charge capable with the 70W USB-C Power Adapter.
How long does the MacBook Air 15″ (M4) take to charge with the Steam Deck 45W?
About 43 min to 50% and 2 h 5 min to full, estimated with the device idle.