Each font sheet has 16 x 6 glyphs.

Inconsolata-8.png  and Inconsolata-8-bold.png  ... glyph is 6x14px
Inconsolata-10.png and Inconsolata-10-bold.png ... glyph is 7x17px
Inconsolata-12.png and Inconsolata-12-bold.png ... glyph is 8x21px