400 mAh Is How Many Wh?
Quick Answer: 400 mAh = 1.48 Wh (at 3.7V)
Popular mAh to Wh Conversions
See Also
- 100 mAh to Wh — 0.37 Wh
- 200 mAh to Wh — 0.74 Wh
- 300 mAh to Wh — 1.11 Wh
- 500 mAh to Wh — 1.85 Wh
- 600 mAh to Wh — 2.22 Wh
- 700 mAh to Wh — 2.59 Wh
- 800 mAh to Wh — 2.96 Wh
- 900 mAh to Wh — 3.33 Wh
- 1,000 mAh to Wh — 3.7 Wh
- 1,100 mAh to Wh — 4.07 Wh
- 1,200 mAh to Wh — 4.44 Wh
- 1,300 mAh to Wh — 4.81 Wh
- 1,400 mAh to Wh — 5.18 Wh
Frequently Asked Questions
How many Wh is 400 mAh?
400 mAh equals 1.48 Wh at 3.7V (Li-ion nominal voltage). The exact Wh depends on the battery voltage: Wh = mAh × V / 1,000.
How do I convert 400 mAh to Wh?
Multiply 400 by the battery voltage, then divide by 1,000. At 3.7V: 400 × 3.7 / 1,000 = 1.48 Wh.
Is 400 mAh allowed on a plane?
At 3.7V, 400 mAh = 1.48 Wh. Airlines allow lithium batteries up to 100 Wh in carry-on luggage. Batteries between 100–160 Wh require airline approval. Batteries over 160 Wh are prohibited on passenger aircraft.
Formula: Wh = mAh × V / 1,000. Results assume nominal battery voltage.
Conversion factors verified against NIST, BIPM
Based on SI definitions (BIPM).
Last reviewed: March 2026
