OpenFront Troop Growth & the 42% Rule
Your army grows every tick toward a ceiling set by your land and cities. Understanding that ceiling — and the slowdown as you approach it — explains most 'why is my army so small' moments.
Quick answer: two things matter — your maximum army (land tiles plus city levels) and how full you are relative to it. Growth per tick is roughly a base amount plus a sublinear term in your current troops, multiplied by the fraction of your ceiling you have not filled. The ceiling, not the clock, is what limits you.
What sets your ceiling
| Input | Effect on maximum army | Notes |
|---|---|---|
| Tiles owned | Sublinear growth with area — doubling tiles does not double the ceiling | Expansion still matters, with diminishing returns per tile |
| City levels | +250,000 maximum troops per city level (live build) | The largest single lever available for gold |
| Player type | Bots and AI nations use their own multipliers; difficulty scales AI ceilings | Relevant in single-player and lobbies with bots |
How growth behaves
- Small army, room to grow — growth is fastest relative to your army; this is the expansion phase, when reinvesting troops into land is cheapest.
- Mid-game — growth continues, but the unfilled fraction of your ceiling shrinks, so troop income slows while your appetite for spending rises.
- Near the ceiling — growth approaches zero. More troops then have to come from more land or more cities, not from waiting.
- After a war — a spent army refills quickly because you are far from your ceiling again; this is the recovery window other players will try to exploit.
The 42% rule — what it actually is
Players commonly say an army around 42% of its maximum is where growth per troop is most efficient, and that pushing far above that is wasteful. The figure is a community heuristic derived from observed growth curves — it is not hard-coded, and the developers do not document it as a designed threshold. Use it as a mental model for 'growth slows as you fill up', not as a switch that flips at a specific percentage.
- Where the intuition is right — growth is genuinely strongest while a large fraction of your ceiling is unfilled.
- Where it misleads — the slowdown is continuous, and the right army size depends on the war you are fighting, not on a fixed share of your ceiling.
- How to use it — as a hint that long periods spent at 80–100% of your ceiling usually mean you need more land or more cities. Buildings
Practical implications
- Build cities when your army sits near its ceiling and you cannot expand safely — the same fix as taking land, paid for in gold.
- Do not measure yourself against a neighbour's army alone; compare land and city levels, which is what their ceiling is made of.
- After a successful war your army refills quickly — decide in advance whether you are consolidating or pushing again, because your neighbours will assume the former.
FAQ
Common questions about this topic.
Is the 42% rule official?
No. It is a community heuristic describing where growth per troop feels most efficient. The game does not document it as a designed threshold.
What is the maximum army based on?
Tiles owned (sublinearly) plus a bonus per city level — 250,000 maximum troops per city level in the live build.
Why does my army stop growing?
Because it is near your ceiling. The fix is more land or more city levels, not waiting.
Can I buy troops with gold?
No — troops grow toward your ceiling; gold buys buildings that raise the ceiling or fund your economy. Custom lobbies can enable infinite-troop host settings.