In Rust every player-built structure slowly loses health unless a tool cupboard (TC) next to it holds enough resources to pay its upkeep. Once the cupboard runs dry – or if there never was one – decay starts, and a piece at full health disappears after a time that depends on its building grade: about 1 hour for twig, 3 hours for wood, 5 for stone, 8 for sheet metal and 12 for armoured (Facepunch’s default server settings, checked October 2026).
Decay removes health at a steady rate, so a wall that has already lost half its hit points has half the time left. Enter the grade and the current health, either as a percentage or as hit points (twig 10, wood 250, stone 500, sheet metal 1,000 and armoured 2,000 HP for walls and foundations), and the calculator gives the time remaining and the health lost per hour. If the cupboard still has upkeep for some hours, add them – decay only starts afterwards.
Community servers sometimes change the decay.scale setting: 2 makes decay twice as fast, 0.5 half as fast. Facepunch adjusts balance in its monthly updates, so check the in-game values if a patch changed decay.
How to use the Rust Decay Calculator
- Building grade
- Enter health as
- Current health
- Current hit points
- Server decay scale — 1 = default. 2 doubles the decay speed.
- Upkeep left in the tool cupboard — 0 if the cupboard is empty or missing.
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
The full-health decay time for the grade is scaled by the fraction of health left and divided by the server decay scale; any remaining upkeep time is added before decay begins.
Worked example
A stone wall at 70% health with an empty cupboard on a default server: 5 h × 0.70 = 3.5 h, or 3 h 30 min. It loses 500 ÷ 5 = 100 HP per hour. With 2 hours of upkeep still in the cupboard the wall survives 5 h 30 min; on a server with decay.scale 2 the decay part halves to 1 h 45 min.
Decay at full health (default server)
| Grade | Wall HP | Full decay | HP lost per hour |
|---|---|---|---|
| Twig | 10 | 1 h | 10 |
| Wood | 250 | 3 h | 83 |
| Stone | 500 | 5 h | 100 |
| Sheet metal | 1,000 | 8 h | 125 |
| Armoured | 2,000 | 12 h | 167 |
Inputs explained
| Field | What to enter |
|---|---|
| Building grade | Choose one: Twig (1 h, 10 HP), Wood (3 h, 250 HP), Stone (5 h, 500 HP), Sheet metal (8 h, 1,000 HP) … |
| Enter health as | Choose one: Percentage, Hit points |
| Current health | In % |
| Current hit points | A number |
| Server decay scale | A number. 1 = default. 2 doubles the decay speed. |
| Upkeep left in the tool cupboard | Units: h, min. 0 if the cupboard is empty or missing. |
What each result means
- Time until it decays away = ([Upkeep left in the tool cupboard] + [full]×[fr]÷[Server decay scale])×3600
- Decay time after upkeep runs out = [full]×[fr]÷[Server decay scale]×3600
- Time left in hours = [Upkeep left in the tool cupboard] + [full]×[fr]÷[Server decay scale]
- Current hit points = [fr]×[mx]
- Health lost per hour of decay = [mx]÷[full]×[Server decay scale]
- Full decay time for this grade = [full]÷[Server decay scale]×3600
Formula
Time left = upkeep time + full decay time × (current HP ÷ max HP) ÷ decay scale · full decay: twig 1 h, wood 3 h, stone 5 h, sheet metal 8 h, armoured 12 h
Worked example
Inputs — Building grade: Stone (5 h, 500 HP); Enter health as: Percentage; Current health: 100 %; Server decay scale: 1; Upkeep left in the tool cupboard: 0 h.
Results — Time until it decays away = 5:00:00; Decay time after upkeep runs out = 5:00:00; Time left in hours = 5 h; Current hit points = 500 HP; Health lost per hour of decay = 100 HP/h; Full decay time for this grade = 5:00:00.
Key terms
- Decay
- Steady loss of health on unprotected structures.
- Upkeep
- Resources in the tool cupboard that pay to prevent decay.
- Tool cupboard (TC)
- The block that grants building privilege and holds upkeep.
- Building grade
- Twig, wood, stone, sheet metal or armoured.
Frequently asked questions
How long does stone take to decay in Rust?
About 5 hours from full health once the tool cupboard is empty (default settings).
How long does twig last?
About 1 hour from full health – twig decays fastest.
How do I stop decay?
Keep wood, stone, metal fragments and high-quality metal in the tool cupboard to pay upkeep for the grades you built.
Does a half-damaged wall decay faster?
It decays at the same rate, but has half the health left, so it disappears in half the time.
What does decay.scale do?
It multiplies decay speed on a server; 0 turns decay off and 2 doubles it.
How much health does a stone wall have?
500 HP; wood has 250, sheet metal 1,000 and armoured 2,000.
Does a destroyed TC protect my base?
Facepunch's wiki notes that a destroyed cupboard with resources inside uses up to 24 hours of upkeep, delaying decay.