Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Canon SX1 IS and Canon SX20 IS side-by-side from the front, back and top in their relative dimensions. Canon SX1 IS has external dimensions of 128 x 88 x 88 mm (5.04 x 3.46 x 3.46″) and weighs 615 g (1.36 lb / 21.69 oz) (including batteries). Canon SX20 IS has external dimensions of 128 x 88 x 87 mm (5.04 x 3.46 x 3.43″) and weighs 600 g (1.32 lb / 21.16 oz) (including batteries).
Below you can see the front-view size comparison of the Canon SX1 IS and the Canon SX20 IS. Canon SX1 IS has the same height and width with Canon SX20 IS. On the other hand, with a thickness of 88mm, it is 1mm thicker.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon SX20 IS is 15g lighter than the Canon SX1 IS but we don't think this will make a significant difference.
Weather Sealing
Unfortunately neither the Canon PowerShot SX1 IS nor Canon PowerShot SX20 IS provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Bridge Cameras with Weather Sealing
LCD Screen Size and Features
Canon SX1 IS's 2.80" LCD screen is slightly larger than Canon SX20 IS's 2.5" screen.