Worked example: Furnace, Fire Crystal 8 → 9 — confirmed from real screenshots (last checked 2026-09-05)
A building's upgrade screen shows a progress bar for the climb to your next level — usually 5 segments — but the "Requires" list only ever shows the cost of your next segment, not what the remaining segments will cost. Working out the real total means adding up every one of them, not just the next one. Here's what that looks like for the Furnace's FC8 → FC9 climb: four identical segments, then a final segment with a different (lower Fire Crystal, higher Refined Fire Crystal) cost.
| Segment | Meat | Wood | Coal | Iron | Fire Crystal | Refined FC | Time |
|---|---|---|---|---|---|---|---|
| 1 | 140.0M | 140.0M | 29.0M | 7.2M | 280 | 30 | 13d |
| 2 | 140.0M | 140.0M | 29.0M | 7.2M | 280 | 30 | 13d |
| 3 | 140.0M | 140.0M | 29.0M | 7.2M | 280 | 30 | 13d |
| 4 | 140.0M | 140.0M | 29.0M | 7.2M | 280 | 30 | 13d |
| 5 (final) | 140.0M | 140.0M | 29.0M | 7.2M | 140 | 60 | 13d |
| Total | 700M | 700M | 145M | 36M | 1,260 | 180 | ~65d |
Time is per-segment with zero speedups applied, run sequentially. Source: confirmed segment-by-segment against real in-game screenshots — see this project's own research notes for the full methodology.
For the whole climb from level 30 to FC10, see Furnace FC1 to FC10: every level's cost, and for all seven buildings together, how many Fire Crystals you need for FC10. To add up any range with your own construction speed and buffs, use the free building upgrade cost calculator.
This is one worked example. FC Crazy reads screenshots of your actual account and works out your real total cost to your next upgrade across Furnace, Embassy, Command Center, and more — plus what's actually blocking you and what's worth claiming today.
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