Enter a speed in meters per minute to convert to surface feet per minute (SFM), or enter SFM to convert back. Both measure the same linear cutting speed; SFM is the standard in North American machining while m/min is used in ISO-metric environments.
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| m/min to SFM (ft/min) | SFM (ft/min) to m/min |
|---|---|
| 5 m/min = 16.4042 ft/min | 50 ft/min = 15.2400 m/min |
| 10 m/min = 32.8084 ft/min | 75 ft/min = 22.8600 m/min |
| 20 m/min = 65.6168 ft/min | 100 ft/min = 30.4800 m/min |
| 30 m/min = 98.4252 ft/min | 150 ft/min = 45.7200 m/min |
| 50 m/min = 164.0420 ft/min | 200 ft/min = 60.9600 m/min |
| 75 m/min = 246.0630 ft/min | 250 ft/min = 76.2000 m/min |
| 100 m/min = 328.0840 ft/min | 300 ft/min = 91.4400 m/min |
| 150 m/min = 492.1260 ft/min | 400 ft/min = 121.9200 m/min |
| 200 m/min = 656.1680 ft/min | 500 ft/min = 152.4000 m/min |
| 250 m/min = 820.2100 ft/min | 600 ft/min = 182.8800 m/min |
| 300 m/min = 984.2520 ft/min | 800 ft/min = 243.8400 m/min |
| 400 m/min = 1,312.3360 ft/min | 1,000 ft/min = 304.8000 m/min |
| 500 m/min = 1,640.4200 ft/min | 1,200 ft/min = 365.7600 m/min |
| 600 m/min = 1,968.5040 ft/min | 1,500 ft/min = 457.2000 m/min |
| 800 m/min = 2,624.6720 ft/min | 2,000 ft/min = 609.6000 m/min |
| 1,000 m/min = 3,280.8400 ft/min | 2,500 ft/min = 762.0000 m/min |
| 1,200 m/min = 3,937.0080 ft/min | 3,000 ft/min = 914.4000 m/min |
| 1,500 m/min = 4,921.2600 ft/min | 3,500 ft/min = 1,066.8000 m/min |
| 2,000 m/min = 6,561.6800 ft/min | 4,000 ft/min = 1,219.2000 m/min |
| 2,500 m/min = 8,202.1000 ft/min | 5,000 ft/min = 1,524.0000 m/min |
| Formulas: ft/min = (m/min) x 3.28084 and m/min = (ft/min) / 3.28084. | |
M/Min To SFM Formula
The following formula converts meters per minute (m/min) to surface feet per minute (SFM). The conversion factor is the exact number of feet in one meter.
SFM = M/Min * 3.28084
Variables:
- SFM = surface feet per minute (ft/min)
- M/Min = speed in meters per minute
- 3.28084 = feet per meter (derived from 1 / 0.3048, the exact SI definition)
Reverse conversion: M/Min = SFM x 0.3048. For quick mental math, m/min x 3.3 gives SFM within 0.6% accuracy, useful for rough shop-floor estimates.
What is SFM in Machining?
SFM (surface feet per minute) is the linear speed at which a cutting tool contacts a workpiece surface. It governs heat generation, chip formation, tool wear, and surface finish more directly than spindle RPM, because the same RPM produces very different cutting speeds depending on tool diameter. North American machinists and tooling manufacturers specify cutting speeds in SFM; European and Asian counterparts use m/min (surface meters per minute, or SMM). Converting between them is essential whenever European-made CNC machines run tooling with American speed specifications, or vice versa.
SFM links to RPM through tool diameter: RPM = (SFM x 3.82) / Diameter(in). In metric terms: RPM = (1000 x m/min) / (3.14159 x Diameter(mm)). A 12 mm carbide end mill cutting aluminum at 244 m/min (800 SFM) requires approximately 6,480 RPM; the same speed on a 25 mm cutter drops to 3,104 RPM. This diameter dependence is why SFM or m/min, not RPM, is the universal language for specifying cutting conditions across different tool sizes.
Recommended Cutting Speeds by Material
Tool material and workpiece material together determine the correct SFM range. Carbide tooling tolerates higher heat than HSS, enabling 3x to 5x higher speeds. The table below shows standard industry ranges in both SFM and the equivalent m/min, making it directly useful when your machine display and your tool catalog use different unit systems.
| Material | HSS (SFM) | HSS (m/min) | Carbide (SFM) | Carbide (m/min) |
|---|---|---|---|---|
| Aluminum alloys | 300 – 1,000 | 91 – 305 | 800 – 2,000+ | 244 – 610+ |
| Free-machining steel | 150 – 300 | 46 – 91 | 400 – 800 | 122 – 244 |
| Medium carbon steel | 100 – 200 | 30 – 61 | 300 – 600 | 91 – 183 |
| Alloy steel | 80 – 150 | 24 – 46 | 250 – 500 | 76 – 152 |
| Stainless steel (304/316) | 40 – 100 | 12 – 30 | 150 – 350 | 46 – 107 |
| Gray cast iron | 50 – 125 | 15 – 38 | 200 – 450 | 61 – 137 |
| Brass / Bronze | 200 – 400 | 61 – 122 | 400 – 800 | 122 – 244 |
| Copper | 150 – 300 | 46 – 91 | 300 – 600 | 91 – 183 |
| Titanium alloys | 50 – 100 | 15 – 30 | 100 – 250 | 30 – 76 |
| Ranges are guidelines for turning and milling operations. Exact values depend on depth of cut, feed rate, coolant use, and specific alloy grade. Verify against tooling manufacturer data sheets for production settings. | ||||
Titanium requires especially low SFM not because it is the hardest material, but because it has poor thermal conductivity (about 6 W/m-K vs. 50 W/m-K for carbon steel). Heat generated at the cutting edge cannot dissipate into the workpiece, concentrating at the tool tip and accelerating wear. Aluminum sits at the opposite extreme: high thermal conductivity and low hardness allow very high SFM, limited mainly by the machine’s top RPM when using small-diameter tools.
