Building & renovation
How much abrasive do you need for sandblasting?
How many kg and bags of abrasive for sandblasting — from surface area, consumption per m² and bag size.
Quick answer
Abrasive is sold by the bag but jobs are priced by the square metre, and what decides the consumption is the state of the steel, not its size. On steel at 6–7 bar with a #5 nozzle:
Advanced settings
Bags to buy
7
- Abrasive needed
- 173 kg
Consumption depends on nozzle size, pressure, media type and operator skill. Garnet and aluminium oxide at ~6–7 bar typically use 8–12 kg/m² for paint on steel. Add loss for dust collection and spillage — recycle systems lower net use.
How it works
| What you are removing | Abrasive |
|---|---|
| Light rust | ~6 kg/m² |
| Paint | 8–12 kg/m² |
| Heavy mill scale | ~18 kg/m² |
Worked example: 15 m² of fence panels at 10 kg/m² with 15% loss → 15 × 10 × 1.15 = 172.5 kg, which is 7 bags of 25 kg. Open blasting outdoors sits at the high end of that loss figure; a recovery cabinet reuses the grit and cuts the total by a third or more.
Recycle cabinets reuse grit and cut net consumption 30–50%; open-blast outdoors loses more to dust and spillage. Garnet cuts faster than slag but costs more per kg — the calculator only sizes quantity; media choice is a separate decision. Always use proper sandblasting respirator and containment.
The choice of media is a health decision before it is a cost one. Abrasives containing free silica are restricted or banned for open blasting in many countries, because the dust that causes silicosis is far finer than anything an ordinary site dust mask stops — that work needs supplied-air breathing equipment, not a filter cartridge. Garnet, slag and glass alternatives exist for this reason. And plan the containment while you plan the kilos: grit and dust travel much further than people expect, and the classic bill after a facade job is not the abrasive but the neighbours' car paint and glazing downwind.
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Frequently asked questions
How many kg per m² for rust on steel?+
Light surface rust: ~5–8 kg/m². Medium paint + rust: ~10–12 kg/m² at 6–7 bar. Heavy scale or thick coatings: 15–20+ kg/m². Pressure, nozzle size and standoff distance change these numbers more than the metal grade.
25 kg bag — how many m² does it cover?+
At 10 kg/m² with 15% loss, one 25 kg bag covers roughly 2.2 m² (25 ÷ 11.5). At lighter 6 kg/m² rust work, about 3.6 m². Always round up — running out mid-job means downtime and moisture flash-rust.
Does recycled grit use less abrasive?+
Yes — cabinet systems recover and reuse media until it breaks down. Net new abrasive per m² can drop 30–50% versus open blast. Factor higher loss % (20–25%) for outdoor open blasting without recovery.
Garnet vs aluminium oxide consumption?+
Similar kg/m² at the same pressure, but garnet often finishes faster (fewer passes) so total time drops. Aluminium oxide is harder and lasts more recycle cycles in a cabinet. Enter your measured kg/m² from a test patch on scrap.
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