Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Canon ELPH 180 and Canon 170 IS side-by-side from the front, back and top in their relative dimensions. Canon ELPH 180 has external dimensions of 95 x 54 x 22 mm (3.74 x 2.13 x 0.87″) and weighs 126 g (0.28 lb / 4.44 oz) (including batteries). Canon 170 IS has external dimensions of 100 x 58 x 23 mm (3.94 x 2.28 x 0.91″) and weighs 141 g (0.31 lb / 4.97 oz) (including batteries).
Below you can see the front view size comparison of Canon ELPH 180 and Canon 170 IS. Canon ELPH 180 is clearly the smaller of the two cameras. Its body is 5mm narrower, 4mm shorter and 1mm thinner than Canon 170 IS.
Here is the back view size comparison of Canon ELPH 180 and Canon 170 IS.
Now lets look at the top view comparison of Canon ELPH 180 and Canon 170 IS.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon ELPH 180 is 15g lighter than the Canon 170 IS but we don't think this will make a significant difference.
Unfortunately neither Canon PowerShot ELPH 180 nor Canon PowerShot ELPH 170 IS (IXUS 170) provides any type of weather sealing in their body, 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 Compact Cameras with Weather Sealing
LCD Screen Size and Features
Canon ELPH 180 and Canon 170 IS's LCD screens has the same diagonal size of 2.7".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.