The official nominal capacity of the original standard Nokia BL-4U battery is 1000 mAh.
However, over its manufacturing lifespan, Nokia released three official capacity variants depending on the phone model it paired with:
1000 mAh: The standard baseline version used for older S40 and Symbian devices like the E66 and 5530 XpressMusic.
1110 mAh: Introduced in late 2011 alongside the Asha 300 series.
1200 mAh: The highest capacity official version released in mid-2013 for the Nokia 301.