As a rough guide, a
- 2lb (900g) loaf tin is about 21cm long, 11cm wide and 7cm high (8 x 4 x 3 inches approx) and a
- 1lb (450g) loaf tin is 16cm long, 11cm wide and 7cm high (6 x 4 x 3 inches).
They do vary quite a bit from brand to brand but this should help you understand what you have got if you have one already.