Angling your tank to live longer in world of tanks?

The formula for calculating the effective armor rating in world of tanks is:

Armor tickness/cos(impact angle)

With an Angle of > 70% always leading to a ricochet, this leads to this table:

Impact Angle    Effective Armour Thickness
    0°                 100%
   10°                 101.54%
   20°                 106.42%
   30°                 115.47%
   40°                 130.54%
   50°                 155.57%
   60°                 200%
   70°                 292.38%
  > 70°                Ricochet

(source: world of tanks effective armor rating)

Which angle to chose depends a lot on the tank you're driving and how it is armored. But in general, having at least a slight angel towards your opponent is a good idea.

For example, if you're driving a tank with 100mm front armor and 80mm side armor, a 45% angle on both front armor would give you an effective front armor of 141mm and effective side armor of 113mm. In this example having the opponent hit your side at an angle would still give a lower chance of penetration than hitting the front armor at a straight angle.

However if the situation is the same, but the tank you're driving only has 60mm side armor this means the effective rating of the side armor would be 85mm, which means you're giving your opponent an opportunity at an easier penetration, in this case it would be still good to present yourself at an angle, but less than 45%. (a 30% angle in this case would give you 115mm front armor and 120mm side armor)

different angling degrees are needed for each tanks to reliably side scrape against enemies or to effectively angle your lower front plate.

tip:

how thick is your side armor? will it get overmatched?

Overmatching occurs when the caliber of shell exceeds your armor thickness 3 times eg: 122mm soviet guns can pen your paper paper thin side armor of 30mm etc

you can get a good overview of the strenghts and weakness of your tank on tanks.gg, it has a live view that shows you how to effectively angle your tank

[edit] 29 Nov 2016

overmatching system will be reworked by wargaming by update 9.17 As of now, things suggested by the WG video can be somewhat translated into a buff to paper armor tanks, sidescraping with paper armor tanks will be possible and there wont be armor overmatch happening.