You might have a misunderstanding about battery capacity when it comes to different units. Most of the time, in mobile phones, power bank, mobile’s battery mostly defined by mAh (milliamp-hours). For Microsoft Surface family it might have noticed that the battery capacity is defined as mWh (milliwatts-hours).

In this tip, we will guide you how to convert from mWh to mAh and vice-versa.

1 Surface Battery Capacity Here is the list of the battery capacity of all Microsoft Surface in measured of both Wh and mAh: Surface Model Watt Hours Milliampere Hour, Volts Est. Battery Life Surface Surface RT 31.5 Wh 4,257 mAh, 7.4 V 8 hours Surface Power Cover 30.0 Wh 4,054 mAh, 7.4 V - Surface 2 31.5 Wh 4,257 mAh, 7.4 V 10 hours Surface 3 27.5 Wh 7,270 mAh, 3.78 V 10 hours Surface Go 26.12 Wh 3,411 mAh, 7.66V 9 hours Surface Go 2 27 Wh - 10 hours Surface Pro Surface Pro 42.0 Wh 5,676 mAh, 7.4 V - Surface Pro 2 42.0 Wh 5,676 mAh, 7.4 V - Surface Pro 3 42.2 Wh 5,547 mAh, 7.6 V 9 hours Surface Pro 4 38.2 Wh 5,087 mAh, 7.5 V 9 hours Surface Pro (2017) 45.0 Wh 5,940 mAh, 7.57 V 13.5 hours Surface Pro 6 45.0 Wh 5,940 mAh, 7.57 V 13.5 hours Surface Pro 7 43.2 Wh 5,702 mAh, 7.57 V 10.5 hours Surface Pro X 38.2 Wh 5,039 mAh, 7.58 V 13 hours Surface Laptop Surface Laptop 45.2 Wh 5,970 mAh, 7.57 V 14.5 hours Surface Laptop 2 45.2 Wh 5,970 mAh, 7.57 V 14.5 hours Surface Laptop 3 13” 45.8 Wh 6,041 mAh, 7.58 V 11.5 hours Surface Laptop 3 15” 45.8 Wh 6,041 mAh, 7.58 V 11.5 hours Surface Book Surface Book 69.0 Wh 9,187 mAh, 7.5 V 12 hours — clipboard 18.0 Wh 2,387 mAh, 7.5 V 3 hours — base 51.0 Wh 6,800 mAh, 7.5 V 9 hours SB with Performance Base 81.0 Wh 10,787 mAh, 7.5 V 16 hours — clipboard 18.0 Wh 2,387 mAh, 7.5 V 3 hours — base 63.0 Wh 8,400 mAh, 7.5 V 13 hours Surface Book 2 13" i5 69.0 Wh 9,187 mAh, 7.5 V 17 hours — clipboard 18.0 Wh 2,387 mAh, 7.5 V 5 hours — base 51.0 Wh 6,800 mAh, 7.5 V 12 hours Surface Book 2 13" i7 75.3 Wh 10,027 mAh, 7.5 V 17 hours — clipboard 18.0 Wh 2,387 mAh, 7.5 V 5 hours — base 57.3 Wh 7,640 mAh, 7.5 V 12 hours Surface Book 2 15" 90.0 Wh 12,000 mAh, 7.5 V 17 hours — clipboard 23.0 Wh 3,066 mAh, 7.5 V 5 hours — base 67.0 Wh 8,933 mAh, 7.5 V 12 hours 2 How to Convert mWh to mAh? In order to convert from mWh (milliwatt-hours) to mAh (milliamp-hours), we have a formula as below: (mAh) = (mWh) / (V) Example: Surface Pro 3 has a battery capacity of 42 Wh or 42,000 mWh has battery capacity in mAh as below: 42,000 mWh / 7.5 V = 5,600 mAh So, Surface Pro 3 has a battery capacity of 5,600 mAh.

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