King Bed is in the UK, a bed 152 x 198 cm (60 x 78 in).
In the US, one that measures 193 x 203 cm (76 x 80 in).
Other definition:
King bed is the size of the bed at a hotel. Standard king bed dimensions are 193 x 203 cm (76 x 80 in) while California King measures 180 x 210 cm (72 x 84 in).