Rust Decay Calculator

See how long a base holds once the Tool Cupboard runs dry. Work out what the cupboard needs each day with the upkeep calculator.

One piece

Grau Health left: 100%

Faces outside Inside the base

Upkeep left in the Tool Cupboard

hours

The cupboard shows this when you open it. 0 = it's already empty.

Starts decaying

–

Gone in

–

Layered walls

Layers

The outer wall decays at full speed; the ones behind it decay at a tenth of the speed until they're exposed. Pick a grade for each layer, outside first.

Full decay times, no upkeep

Grau	Outside	Inside
Ramos	1 h	10 h
Madeira	3 h	30 h
Stone	5 h	50 h
Chapa de Metal	8 h	80 h
Blindado	12 h	120 h

Special cases

C4 placed outside your building privilege	destroyed after 24 hours
Player-built boats	start decaying after 24 hours, then take 12 hours
Legacy wood shelters	decay unless the owner uses the door once a day (TC upkeep inside its range)
Monument blockers (since Sep 2026)	start decaying if not destroyed within 24 hours
Power Plant heavy fuses	last 4× longer when 10 or fewer players are online
Hot air balloons stuck on something	decay much faster

How decay works

A building joined to a Tool Cupboard that holds enough upkeep doesn't decay at all.
When one resource runs out, only the pieces built from it start to decay - a stone base with no stone in the TC decays even with wood and metal left.
With no upkeep, a piece facing the open air goes from full health to nothing in the times below. Pieces inside the base decay at a tenth of that rate.
Bases decay from the outside in: once an outer wall is gone, the wall behind it is exposed and decays at the full rate.
Doors, window bars and floor or wall frame inserts cost upkeep and decay like building pieces. High external walls have cost 20% upkeep since August 2026.
Deployables inside a Tool Cupboard's range don't decay; outside it, they decay only when nothing shelters them from above.

Limits

Times are vanilla server defaults; servers change them with the decay.* settings, and official Hardcore doubles upkeep.
Facepunch doesn't say whether health drops evenly over time - this assumes it does.
How the game decides what counts as inside isn't published, so the layered-wall estimate is a guide, not a promise.
Current decay times for ordinary deployables (boxes, furnaces, sleeping bags) aren't published - the last official figures are from 2016.

Confidence: confirmed for grade times, the 10% inside rate and outside-in order; unconfirmed for even health loss and the inside test. Checked 2026-11-13. Sources: Facepunch - Devblog 189 (Building 3.0: upkeep and decay); Facepunch - Devblog 190 (doors need upkeep; deployables protected); Facepunch Rust wiki - the Tool Cupboard; Facepunch commit - inside blocks decay at 10%; Facepunch - Power Trip (high walls 20% upkeep, 2026-08-06); Facepunch - Shipshape (boat decay); Facepunch - Eye in the Sky (C4 decay, 2023-03-02); Facepunch - Breach and Clear (monument blockers, 2026-09).

How long until a Rust base decays: pick a building grade, its health and whether it faces outside, add the upkeep left in your Tool Cupboard, and see when each piece - and each layer of a honeycombed wall - falls.

Perguntas frequentes

With no upkeep, an outside piece goes from full health to destroyed in 1 hour for twig, 3 for wood, 5 for stone, 8 for sheet metal and 12 for armored. Pieces inside decay at a tenth of that rate, so the core of a base lasts much longer.

Not while the cupboard holds enough upkeep. When a resource runs out, the pieces built from it start to decay, starting with the outside.

Yes. Each wall behind the outer one only decays at 10% speed until the wall in front of it is gone, so every extra layer adds most of a full decay time.