Unlike character level where you kill monsters for EXP, job level increases when you perform actions so it doesn't matter what monsters you fight, it only count actions you select. All commands you selected during the battle count as actions. For example, if you select Attack, it will count as 1 action, using magic Cure counts as another action and so on. Unfortunately, "Front" and "Rear" do not count as actions.
All jobs from level 1 to 14 need 5 actions to level up. After that, each job has different number of actions. Below is a list of number of actions in average needed for each job after level 14:
| Job | Number of Actions (Level 1 - 14) | Number of Actions (Level 14+) |
|---|---|---|
| Freelancer | 5 | 5 |
| Warrior | 5 | 7 |
| Monk | 5 | 7 |
| Thief | 5 | 6 |
| Black Mage | 5 | 10 |
| White Mage | 5 | 10 |
| Red Mage | 5 | 8 |
| Ranger | 5 | 7 |
| Knight | 5 | 8 |
| Scholar | 5 | 4 |
| Geomancer | 5 | 7 |
| Dragoon | 5 | 6 |
| Viking | 5 | 7 |
| Dark Knight | 5 | 7 |
| Evoker | 5 | 10 |
| Bard | 5 | 6 |
| Black Belt | 5 | 7 |
| Devout | 5 | 10 |
| Magus | 5 | 10 |
| Summoner | 5 | 8 |
| Sage | 5 | 10 |
| Ninja | 5 | 8 |
| Onion Knight | 5 | 13 |
Farming Strategy
The best location to farm job level is the grassland between Altar Cave and Ur. You don't need a powerful monster but a Goblin is enough.
Start by changing everyone to the same job so that they can level up at the same time, put everyone in the back row to reduce the damage, then start running around the grassland. Once the the battle, everyone use "Guard" for the first round, this will count as 1 action for everyone, then press the auto battle button for number of actions needed. For example, if you 7 actions to level up, you can guard until round 6 and kill the Goblin at round 7.
Watch the video below: