# Rust Decay Calculator URL: https://speedycalculator.com/calculators/other/rust-decay/ Last updated: 2026-10-30 > The Rust decay calculator tells you how long a building block, wall or door has left before decay destroys it, from its building grade (twig, wood, stone, sheet metal or armoured), its current health in percent or hit points, the server decay scale and any upkeep still in the tool cupboard. ## Inputs - 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 (h, min) — 0 if the cupboard is empty or missing. ## Results - Time until it decays away - Decay time after upkeep runs out - Time left in hours - Current hit points - Health lost per hour of decay - Full decay time for this grade ## 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 ``` ## Explanation 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) GradeWall HPFull decayHP lost per hourTwig101 h10Wood2503 h83Stone5005 h100Sheet metal1,0008 h125Armoured2,00012 h167 ### Inputs explained FieldWhat to enterBuilding gradeChoose 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 asChoose one: Percentage, Hit pointsCurrent healthIn %Current hit pointsA numberServer decay scaleA number. 1 = default. 2 doubles the decay speed.Upkeep left in the tool cupboardUnits: 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 ## 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. ## FAQ **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. ## Sources - [Facepunch Rust Wiki – The Tool Cupboard](https://wiki.facepunch.com/rust/The_Tool_Cupboard) - [Rust – official site](https://rust.facepunch.com/)