What bonus you gain with every level of off/def?

For every upgrade for defense(armoury) or for attack(blacksmith),
one soldier gain 1.5% procents.

        Level               Procent

           1                   1,5
        2                   3
        3                   4,5
        4                   6
        5                   7,5
        6                   9
        7                   10,5
        8                   12
        9                   13,5
       10                  15
       11                  16,5
       12                  18
       13                  19,5
       14                  21
       15                  22,5
       16                  24
       17                  25,5
       18                  27
       19                  28,5
       20                  30

Example: an imperian which is upgraded at level 20 in blacksmith
will have the next power of attack:

70 + 70 * 30% (21 - the level 20 bonus in blacksmith) = 91.

The bonus from the hero it is added only for attack power of the troop
and it is not like a bonus from the blacksmith or the armoury.

Example: one imperian with level 20 in blacksmith, with a hero
with 20% attack bonus and with lvl 20 at offense from blacksmith:

70 + 70 * 30% (21 - bonus for level 20 in blacksmith)

+ 70 * 20% (14 - bonus from the hero) = 105
(the best attack on every unity of crop).

The same example is for armoury.

source: http://www.travian0.com

See also:

• Troop Efficiency Calculations
• Settler Graphic Pack for you travian
• Travian Calculations & Formulae
  
• Travian Script: Introduction
• Carebear Profile