Maximal Vitality Per Level in FrontierVille

maximal energy gains at a rate of +1 every 2 levels until level 10. Then, a player will get +1 vitality every 5 levels.
At level 1 a player has 10 vitality, at level 2 it increases to 11.
At level 4 the maximal energy increases to 12, and so on until level 10 when a player has 15 vitality.
A player stays at 15 Max energy until level 15 when they'll receive +1 to their maximal, bringing them up to 16.
Aft level 15 they'll receive +1 every 5 levels, so at levels 20, 25, 30, 35, 40 and 45, +1 will be added.
After level 50, the player receives +1 to their max energy every 10 levels.
Remember that adding a spouse will give an extra 3 maximum vitality and a kid will add +1.
Some collections and quests will add to your max energy too, so read carefully when you complete a quest or collection.
You may also purchase Beef Jerky in the Market, which will +1 in addition to replacement your energy Bar.
Here is a chart that will show you the utmost vitality you will have on each level:

 

Level  Energy 
1 10
2 11
3 11
4 12
5 12
6 13
7 13
8 14
9 14
10 15
11 15
12 15
13 15
14 15
15 16
16 16
17 16
18 16
19 16
20 17
21 17
22 17
23 17
24 17
25 18