So... ask:
Dimension = 19 x 18 pixels • Filesize = 380 bytes each

Why not
Dimension = 12 x 18 pixels • Filesize = 220 bytes each

It's all in the question:
Dimension = 12 x 18 pixels • Filesize = 220 bytes each

Certainly a question:
Dimension = 13 x 17 pixels • Filesize = 280 bytes each

Don't mind asking:
Dimension = 10 x 16 pixels • Filesize = 200 bytes each

A straight question:
Dimension = 11 x 20 pixels • Filesize = 240 bytes each