Sandblasting calculator for blast jobs on steel, concrete and wood. It works out nozzle hours, abrasive pounds and bags, compressor CFM, and the job cost and quote from your rates.
Pick the surface condition to fill a typical blast rate, or type your own.
Abrasive and Air Supply
Job Cost and Quote
Cost Breakdown Chart
Nozzle Air and Abrasive Chart
Clemco chart values for one nozzle at 100 psi, abrasive scaled from the chart basis of 100 lb/ft³ to your bulk density. The last column adds one breathing hood and your 50% reserve.
| Nozzle | Air (CFM) | Abrasive (lb/hr) | Compressor (hp) | With Hood and Reserve |
|---|---|---|---|---|
| #2, 1/8 in | 20 | 123 | 5 | 60 CFM |
| #3, 3/16 in | 45 | 264 | 10 | 98 CFM |
| #4, 1/4 in | 81 | 494 | 18 | 152 CFM |
| #5, 5/16 in | 137 | 812 | 31 | 236 CFM |
| #6, 3/8 in | 196 | 1,152 | 44 | 324 CFM |
| #7, 7/16 in | 254 | 1,584 | 57 | 411 CFM |
| #8, 1/2 in | 338 | 2,024 | 75 | 537 CFM |
Step-by-Step Math
- Blasting time = A ÷ (R × N) = 1,000 sq ft ÷ (75 sq ft/hr × 1) = 13.3 hr.
- Abrasive = time × flow × N × (1 + allowance) = 13.3 hr × 494 lb/hr × 1 × 1.10 = 7,245 lb, or 7.25 lb per sq ft.
- Air = (81 CFM nozzle + 20 CFM hood) × 1 = 101 CFM; with 50% reserve = 152 CFM, about 33.7 hp of compressor.
- Cost = labor $867 + equipment $600 + abrasive $1,449 + disposal $217 + setup $250 = $3,383.
- Quote = $3,383 × 1.25 = $4,229, or $4.23 per sq ft.
- Result: 7,245 lb of Abrasive.
Sandblasting Calculator Example: 1,000 sq ft of Rusty Steel
A 1,000 sq ft steel surface with light rust or old paint, blasted with one #4 nozzle at 100 psi, takes about 13.3 hours of nozzle time and 7,245 lb of abrasive. That is 145 bags of 50 lb, or 7.25 lb per square foot.
The air side needs a compressor of at least 152 CFM, about 34 hp. At $65 an hour for labor, $45 for equipment, $0.20 per lb of media and $60 per ton for disposal, the job costs $3,383 and quotes at $4,229 with a 25% markup.
Every sandblasting calculator answer starts from two rates: how fast one nozzle cleans the surface, and how fast it throws abrasive. Time comes from the first; media, air and most of the cost follow from time.
T is the blasting time in hours, A is the surface area, R is the cleaning rate of one nozzle in sq ft per hour, and N is the number of nozzles working at once. At 75 sq ft/hr, 1,000 sq ft takes 1,000 ÷ 75 = 13.3 hours.
That figure is nozzle-on time, not time on site. Setup, masking, pot refills and cleanup come on top. At 8 hours of actual blasting a day, the example fills 1.67 days, and a second nozzle with its own blaster cuts it to 6.7 hours.
How Much Blast Media per Square Foot
Plan on 5 to 10 lb of abrasive per square foot. Target Products gives that range and notes it moves with nozzle size and pressure; its own estimates use 7.5 lb per square foot. In metric, that range is 24 to 49 kg per square meter.
M is the abrasive to order, F is the abrasive flow of one nozzle in lb per hour, and W is the allowance for spills, rebound and the last bag that never empties. With 13.3 hours at 494 lb/hr and a 10% allowance, M = 7,245 lb.
A sandblasting calculator that ties media to blasting time gives a better number than a flat lb-per-sq-ft rule, because it reacts to nozzle size and pressure. Heavy rust that halves the cleaning rate doubles the hours, and the abrasive doubles with them.
Cleaning rate rises with the nozzle. A #7 at 100 psi throws 1,584 lb/hr, 3.2 times a #4, and cleans about 3.2 times the area. Light rust at 75 sq ft/hr on a #4 runs about 240 sq ft/hr on a #7, close to the 230 BlastOne uses as its base rate.
| Area (sq ft) | At 5 lb/sq ft (lb) | At 7.5 lb/sq ft (lb) | At 10 lb/sq ft (lb) | 50 lb bags at 7.5 lb/sq ft | 100 lb bags at 7.5 lb/sq ft |
|---|---|---|---|---|---|
| 100 | 500 | 750 | 1,000 | 15 | 8 |
| 250 | 1,250 | 1,875 | 2,500 | 38 | 19 |
| 500 | 2,500 | 3,750 | 5,000 | 75 | 38 |
| 1,000 | 5,000 | 7,500 | 10,000 | 150 | 75 |
| 2,000 | 10,000 | 15,000 | 20,000 | 300 | 150 |
| 5,000 | 25,000 | 37,500 | 50,000 | 750 | 375 |
Nozzle flow charts are measured with abrasive that weighs 100 lb per cubic foot. A lighter media meters out fewer pounds per hour through the same nozzle, so scale the chart flow by your media's bulk density before you order.
A sandblasting calculator result far outside 5 to 10 lb per sq ft usually means the cleaning rate does not suit the nozzle.
BlastOne's worn-nozzle compendium uses 800 lb per hour per blaster against a 100 sq ft per hour baseline on a #7 nozzle, which works out to about 8 lb per square foot, inside the same 5 to 10 lb band.
How Many CFM to Sandblast
A #4 nozzle at 100 psi uses 81 CFM, and a #6 uses 196 CFM, per the Clemco compressed air and abrasive consumption chart.
Add about 20 CFM for the blaster's supplied-air hood, then add reserve. Two nozzles with two hoods double the air, so a sandblasting calculator for a two-man crew starts at 202 CFM before reserve.
Q is the compressor size in CFM and r is the reserve as a decimal. The Paint Booth compressor guide cites Clemco's 50% reserve and 20 CFM hood figure. For one #4 nozzle that gives (81 + 20) × 1.5 = 152 CFM.
| Nozzle | Orifice (in) | Air at 90 psi (CFM) | Air at 100 psi (CFM) | Abrasive at 100 psi (lb/hr) | Compressor at 100 psi (hp) | With hood and 50% reserve (CFM) |
|---|---|---|---|---|---|---|
| #2 | 1/8 | 18.5 | 20 | 123 | 5 | 60 |
| #3 | 3/16 | 41 | 45 | 264 | 10 | 98 |
| #4 | 1/4 | 74 | 81 | 494 | 18 | 152 |
| #5 | 5/16 | 126 | 137 | 812 | 31 | 236 |
| #6 | 3/8 | 173 | 196 | 1,152 | 44 | 324 |
| #7 | 7/16 | 240 | 254 | 1,584 | 57 | 411 |
| #8 | 1/2 | 309 | 338 | 2,024 | 75 | 537 |
The reserve is there because nozzles wear open. A #4 that wears to the size of a #5 draws 137 CFM instead of 81, which is 69% more air. A compressor sized with no reserve loses nozzle pressure as soon as the liner starts to wear.
A sandblasting calculator sizes the compressor for the nozzle you plan to run, not the one you will end with. Size the air for the next nozzle up when the job is long or the media is hard, since that is where the nozzle will be by the last day.
What Pressure Is Good for Sandblasting
Run 100 psi at the nozzle for steel work. BlastOne's compendium rates 100 psi as 100% efficiency for any orifice size, with output falling to 86% at 90 psi, 74% at 80 psi and 47% at 50 psi.
Pressure at the compressor is not pressure at the nozzle. Long hose, small couplings and a worn nozzle all drop it, so check it with a needle gauge pushed into the hose right behind the nozzle while abrasive is flowing.
Low pressure costs twice. The surface cleans more slowly, so labor hours rise, and a sandblasting calculator that holds the cleaning rate fixed will under-call those hours. At 80 psi and 74% efficiency, the 1,000 sq ft job grows from 13.3 to 18.0 hours.
Media use climbs too, because abrasive flow falls less than cleaning speed. The same job goes from 7.25 to 8.09 lb per square foot at 80 psi, so a weak compressor costs abrasive as well as labor.
Softer substrates need less. Wood, brick, fiberglass and detail work are usually blasted with a small nozzle at lower pressure, where a light touch matters more than speed, so the steel figures above do not carry over.
Sandblasting Cost per Square Foot and per Hour
Hired sandblasting runs about $1.50 to $7 per square foot in the US, and blasting labor runs about $50 to $80 an hour, with complex work up to $300 an hour, per HomeAdvisor's sandblasting cost guide, updated June 2026.
| Surface or method | Price per sq ft (USD) | Price per m² (USD) |
|---|---|---|
| Tile | 1.50-3.00 | 16-32 |
| Stucco | 1.50-3.50 | 16-38 |
| Wood | 2.00-3.00 | 22-32 |
| Brick | 2.50-3.00 | 27-32 |
| Concrete | 2.50-3.50 | 27-38 |
| Asphalt | 2.00-5.00 | 22-54 |
| Wrought iron | 4.00-8.00 | 43-86 |
| Wet sandblasting | 1.70-3.25 | 18-35 |
| Dry sandblasting | 2.00-4.50 | 22-48 |
| Dry ice blasting | 3.50-5.00 | 38-54 |
The per-square-meter column is the US price times 10.764 sq ft per m². It is a unit change, not a local rate, so a quote in the UK or anywhere else still depends on local labor, media and disposal prices. Treat these ranges as a check on a sandblasting calculator quote, not a substitute for one.
The $4.23 per sq ft from the 1,000 sq ft example sits inside HomeAdvisor's range. Its hourly figure is higher than a labor rate because it wraps media, equipment, disposal and markup into each blasting hour: $4,229 ÷ 13.3 hr = $317 per hour.
How to Price a Sandblasting Job
Build the price from five costs, then add markup. Pricing straight from a per-square-foot range misses the jobs where rust, access or disposal push the real cost to one end of it.
C is the job cost, L is labor per blaster-hour, E is equipment and fuel per nozzle-hour, p is the media price per lb, d is disposal per lb and S is setup, masking and cleanup. The quote is C × (1 + markup).
In the example, labor is $867, equipment $600, abrasive $1,449, disposal $217 and setup $250, for $3,383. Media and disposal together are 49% of cost, so the abrasive price on your supplier's quote moves the bid more than any other single number.
This five-cost method is what a sandblasting cost estimator or pricing sheet runs on, and it shows what changes when the job does. Doubling the area doubles everything except setup; switching from light rust to heavy rust roughly doubles hours, media and disposal at once.
Disposal depends on what came off the surface. Old lead or chromate paint can turn spent abrasive into a hazardous waste stream that costs far more per ton than plain spent grit, so test the coating before you price it.
Steel grit changes the media math. It goes back through the pot many times, so the grit to buy and to dispose of is the blasted weight divided by the number of uses. At 20 uses, the 7,245 lb that passes through the nozzle needs only 362 lb of new grit.
The trade-off is equipment. Recycling needs a recovery system to sweep, sieve and return the grit, and that cost belongs in the hourly equipment rate. A sandblasting calculator with recycled grit should still check the 5 to 10 lb per sq ft band on blasted weight, not purchased weight.
Grit Size and Surface Profile
The best grit size is the one that leaves the profile your coating calls for. Coarser grit cuts a deeper anchor pattern; finer grit leaves a shallower one and a smoother finish. The coating data sheet gives the profile in mils.
The Clemtex job estimation guide pairs slag abrasive grades with profiles: grade #6 for about 1.5 mils, #4 for 2 mils, #3 for 2.5 mils and #2 for 3 mils. It also lists cleanliness grades from brush-off blast (SSPC-SP 7) to white metal (SSPC-SP 5).
Grit size does not enter a sandblasting calculator directly, but the grade you pick sets the bulk density and how fast the media breaks down, so it changes the flow and the pounds per square foot.
Cleanliness grade changes time and media as much as rust does. A white metal blast removes every trace of rust and scale, so it cleans fewer square feet per hour than a commercial blast on the same steel.
What is the scale for abrasive hardness?
Abrasive hardness is usually given on the Mohs scale, from 1 for talc to 10 for diamond. Harder media cuts faster and breaks down less, while softer media such as walnut shell or baking soda strips coatings without cutting into the base material.
Surface Area to Blast for Walls, Plates, Pipes and Tanks
A flat wall or plate is length times width, doubled if both faces get blasted. A 40 ft by 12 ft wall is 480 sq ft on one side and 960 sq ft on both.
A pipe or tank shell is π × outside diameter × length. A tank 12 ft across and 40 ft long has 1,508 sq ft of outer shell, not counting the heads; blasting the inside too roughly doubles it, since the inner surface is almost the same size.
Add structural steel, flanges and stiffeners as separate areas. Edges and corners take longer per square foot than open plate, so a sandblasting calculator run on flat area alone will under-call time on complex steelwork.
Blasting is often the step before welding repairs or coating. If the work includes new welds, the Welding Calculator estimates the filler and weld metal, and punched parts can be sized first with the Punch Force Calculator.
Silica Sand and Sandblasting Safety Rules
Dry blasting with silica sand throws respirable crystalline silica into the air. In the US, OSHA's silica standards set a permissible exposure limit of 50 micrograms per cubic meter averaged over an 8-hour day, which drives the hood, air and containment you need.
That is why many contractors blast steel with coal slag, garnet, steel grit or other low-silica media. The media change alters bulk density and flow rate, so rerun the sandblasting calculator with the new density and flow rather than reusing a silica-sand figure.
What Is a Sandblasting Calculator?
A sandblasting calculator estimates the blasting hours, abrasive tonnage, compressor size and job price for a surface from its area, cleaning rate, nozzle size and nozzle pressure. It turns one set of job inputs into a material order and a quote.
How do I estimate time for a sandblasting job?
Divide the area by the cleaning rate times the number of nozzles. A sandblasting calculator gives that nozzle time; add setup, refills and cleanup, which are not part of nozzle time. For 1,000 sq ft at 75 sq ft per hour with one nozzle, that is 13.3 hours of blasting before the extras.
BlastOne's blast time guide uses 230 sq ft per hour per nozzle at 100 psi for near-white blasting as its base, and notes that a second operator roughly doubles the area per hour.
How to calculate powder factor in blasting?
Powder factor belongs to explosive rock blasting, not abrasive blasting. It is the weight of explosive divided by the volume or weight of rock broken, such as lb of explosive per cubic yard, and it plays no part in a sandblasting estimate.