Sandblasting CFM Chart & Nozzle Calculator
CFM needed for sandblasting at every nozzle size and pressure. Plus hose pressure loss, breathing air demand, and fuel burn.
Updated November 2026
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Sandblasting Nozzle Size Chart: CFM by Nozzle and PSI
Use this reference chart to quickly look up CFM requirements by nozzle size and working pressure. For exact calculations including hose loss, breathing air, and altitude derate, use the calculator above.
| Nozzle Size | Orifice | 60 PSI | 80 PSI | 100 PSI | 125 PSI | 140 PSI |
|---|---|---|---|---|---|---|
| #3 | 3/16" | 29 | 37 | 45 | 55 | 61 |
| #4 | 1/4" | 53 | 67 | 81 | 99 | 109 |
| #5 | 5/16" | 89 | 113 | 137 | 167 | 185 |
| #6 | 3/8" | 128 | 162 | 196 | 239 | 264 |
| #7 | 7/16" | 165 | 210 | 254 | 309 | 343 |
| #8 | 1/2" | 220 | 279 | 338 | 412 | 456 |
| #10 | 5/8" | 357 | 452 | 548 | 667 | 739 |
| #12 | 3/4" | 511 | 647 | 784 | 955 | 1057 |
Air at 100 PSI: #3–#8 from Clemco’s air consumption chart, #10 and #12 from Marco’s. Other pressures scale with absolute pressure, (PSI + 14.7) / 114.7, which matches the published charts within about 2% from 50 to 140 PSI. Pressures are at the nozzle. Worn nozzles draw more: a #6 worn to 7/16″ draws a #7’s 254 CFM, 29% more (Clemco nozzle wear chart).
Is your nozzle worn?
Push a nozzle gauge into the bore and enter what it reads. Replace the nozzle once it is 1/16″ over its original size, one nozzle number. This uses the nozzle, pressure, air line, blasters and altitude from the calculator above, and assumes every nozzle on the compressor is worn the same.
New #6 (3/8"). Inches (7/16 or 0.44) or a nozzle number (#7).
Nozzle time, not time on site
Optional. Leave blank to skip media dollars.
Cost of the wear, 1 blaster
Your compressor keeps up, but the extra air through the air line drops the nozzle to 99 PSI, about 1% less production.
Production loss is 1.5% per PSI under 100 at the nozzle, with no credit above 100. That is the production loss column of the “Pressure Loss in Compressor Air Line” chart (reprint), and GMA Garnet and BlastOne state the same rule. Bores between nozzle numbers are interpolated by orifice area between chart rows. Media pounds use Clemco’s chart rate for the bore at 100 lb per cu ft. As examples only (November 2026): Clemtex lists tungsten carbide nozzles at 300 to 1,000 hours and boron carbide at 750 to 1,500 hours (Clemtex), and its nozzle orifice gauge at $115 (Clemtex).
Data sources
- Nozzle CFM at 100 PSI: Clemco “Compressed-Air & Abrasive Consumption” (#3–#8), Marco blast nozzle guide (#10, #12)
- Pressure-flow relationship: choked nozzle flow, linear in absolute pressure; matches the Clemco, Marco and Empire charts
- Air line loss: Clemco “Pressure Loss in Compressor Air Line” (150 CFM, 100 PSI, Surface Finishing Co. reprint), scaled by flow squared. The 2″ figure is extrapolated (estimate). Minimum line sizes: Clemco “Minimum Compressor Air Line Diameter”
- Altitude: about 3% capacity loss per 1,000 ft (Powerex, “Compressor Sizing for Altitude”)
- Breathing air: 15 CFM per blaster, the Clemco Apollo 600 HP Type CE spec (20 CFM with a climate-control tube). The regulatory floor is 6 CFM for loose-fitting hoods (NIOSH, 42 CFR 84.162)
- Diesel fuel: 0.015 gal per CFM per hour at full load (Doosan Portable Power spec sheets, 185–825 CFM units)
- Compressor headroom: 25% is our own margin. Clemco’s system sizing table adds 50% reserve and 20 CFM per helmet, so it sizes larger
- Nozzle wear: Clemco “Effects of Nozzle Wear on Air Consumption” (No. 7, 7/16″: 254 CFM, 29% more than No. 6). Bores between nozzle numbers are interpolated by orifice area (diameter squared) between neighbouring chart rows, for air and media alike
- Production loss: 1.5% per PSI under 100 at the nozzle, the production loss column of the air line loss chart above (11.1 PSI lost, 16.6% production lost). Stated by GMA Garnet (“Blasting efficiency drops 1.5% for every 1 psi below 100”) and BlastOne. No source puts a number on production lost by a worn nozzle that still gets full pressure, so the calculator counts none
- Replace at 1/16″ over the original bore: Clemco nozzle copy (via Kleen Blast) and BlastOne
- Nozzle life and gauge price, as examples (November 2026): Clemtex nozzles (tungsten carbide 300–1,000 hours, boron carbide 750–1,500 hours), Clemtex nozzle orifice gauge ($115)
Results are estimates based on industry-published data. Verify against manufacturer specs for your specific equipment.
Common questions
What size compressor do I need for sandblasting?
It depends on your nozzle size. At 100 PSI a #5 nozzle needs about 137 CFM, a #6 needs 196 CFM, a #7 needs 254 CFM and a #8 needs 338 CFM (Clemco chart). Add 15 CFM per blaster for breathing air, allow for altitude, and add 25% headroom. One blaster on a #6 or #7 fits a 375 CFM compressor; a #8 needs 750 CFM. Two blasters on #6 or #7 nozzles need 750 CFM.
How much CFM does a #6 blast nozzle use?
A #6 (3/8") nozzle uses about 196 CFM at 100 PSI and about 239 CFM at 125 PSI. A blast nozzle runs choked, so air flow rises in step with absolute pressure (gauge PSI plus 14.7), not with its square root. Going from 50 to 100 PSI raises a #6 from about 111 to 196 CFM, 77% more air.
How much does hose length affect blast pressure?
It depends on the air line size and how much air runs through it. Loss rises with the square of the flow. With a #6 at 100 PSI, every 50 feet of air line costs about 19 PSI on 3/4", 4.1 PSI on 1", 1.2 PSI on 1-1/4" and 0.3 PSI on 1-1/2" (scaled from Clemco's air line loss chart). Clemco's minimum air line for a #6 is 1-1/2". Keep lines short and at least that wide.
How much diesel does a blast compressor burn?
About 0.015 gallons per CFM per hour at full load, based on Doosan spec sheets. A 375 CFM compressor burns about 5.6 gal/hr at full load and a 750 CFM unit about 11.3 gal/hr. Part-load burn is lower.
Does altitude affect compressor output?
Yes. Compressors lose about 3% of their capacity per 1,000 feet of elevation (Powerex). At 5,000 feet you need about 18% more rated capacity than at sea level to deliver the same air.
How much CFM do I need for sandblasting?
The CFM you need depends on your nozzle size. At 100 PSI: #5 needs 137 CFM, #6 needs 196 CFM, #7 needs 254 CFM. Add 15 CFM per blaster for breathing air, allow about 3% per 1,000 ft of altitude, and add 25% compressor headroom. See the CFM chart above for every nozzle size at multiple pressures.
When should I replace a blast nozzle?
Check the bore with a nozzle gauge and replace the nozzle once it is 1/16" over its original size (Clemco, BlastOne). That is one nozzle number: a #6 (3/8") worn to 7/16" has the bore of a #7 and draws a #7's air, 254 CFM at 100 PSI instead of 196, 29% more (Clemco nozzle wear chart).
How much does a worn nozzle cost?
It depends on whether your compressor keeps up. Two blasters on #6 nozzles share a 450 CFM compressor, which leaves 210 CFM per nozzle after breathing air. A new #6 needs 196 CFM and holds 100 PSI. Worn to 7/16", it needs 254, so the pressure at the nozzle falls to about 80 PSI. Production drops about 1.5% for every PSI under 100, so that is about 30% less blasting: about $179 per blaster per day at $100/hr and 6 blast hours. If the compressor has air to spare, the pressure holds and the worn nozzle costs extra air and media instead of production.
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