- D
- Diameter: of the cutter or drill, or of the workpiece on a lathe
- n
- Spindle speed in revolutions per minute (rpm)
- v
- Cutting speed: how fast the cutting edge moves through the material, in m/min or surface feet per minute (SFM)
Cutting speeds by material
| Material | HSS (m/min) | Carbide (m/min) | HSS (SFM) | Carbide (SFM) |
|---|---|---|---|---|
| Aluminium | 90 | 300 | 295 | 984 |
| Brass and bronze | 60 | 180 | 197 | 591 |
| Plastics | 60 | 150 | 197 | 492 |
| Mild steel | 30 | 120 | 98 | 394 |
| Cast iron | 20 | 90 | 66 | 295 |
| Alloy and tool steel | 15 | 80 | 49 | 262 |
| Stainless steel | 12 | 70 | 39 | 230 |
Plastics means acrylic, nylon and acetal; alloy and tool steel are annealed (not hardened). Reduce the speeds for small or old machines, long tools, no coolant or interrupted cuts. Carbide needs a rigid machine to use its higher speeds.
Spindle speed (rpm): HSS, metric tools
| Tool | Aluminium (rpm) | Brass and bronze (rpm) | Plastics (rpm) | Mild steel (rpm) | Cast iron (rpm) | Alloy and tool steel (rpm) | Stainless steel (rpm) |
|---|---|---|---|---|---|---|---|
| 1 mm | 28648 | 19099 | 19099 | 9549 | 6366 | 4775 | 3820 |
| 2 mm | 14324 | 9549 | 9549 | 4775 | 3183 | 2387 | 1910 |
| 3 mm | 9549 | 6366 | 6366 | 3183 | 2122 | 1592 | 1273 |
| 4 mm | 7162 | 4775 | 4775 | 2387 | 1592 | 1194 | 955 |
| 5 mm | 5730 | 3820 | 3820 | 1910 | 1273 | 955 | 764 |
| 6 mm | 4775 | 3183 | 3183 | 1592 | 1061 | 796 | 637 |
| 8 mm | 3581 | 2387 | 2387 | 1194 | 796 | 597 | 477 |
| 10 mm | 2865 | 1910 | 1910 | 955 | 637 | 477 | 382 |
| 12 mm | 2387 | 1592 | 1592 | 796 | 531 | 398 | 318 |
| 16 mm | 1790 | 1194 | 1194 | 597 | 398 | 298 | 239 |
| 20 mm | 1432 | 955 | 955 | 477 | 318 | 239 | 191 |
| 25 mm | 1146 | 764 | 764 | 382 | 255 | 191 | 153 |
The diameter is the cutter or drill for milling and drilling, the workpiece for turning. If your machine can't reach the speed, run at its top speed and reduce the feed to match (feed = rpm × flutes × feed per tooth).
Spindle speed (rpm): carbide, metric tools
| Tool | Aluminium (rpm) | Brass and bronze (rpm) | Plastics (rpm) | Mild steel (rpm) | Cast iron (rpm) | Alloy and tool steel (rpm) | Stainless steel (rpm) |
|---|---|---|---|---|---|---|---|
| 1 mm | 95493 | 57296 | 47746 | 38197 | 28648 | 25465 | 22282 |
| 2 mm | 47746 | 28648 | 23873 | 19099 | 14324 | 12732 | 11141 |
| 3 mm | 31831 | 19099 | 15915 | 12732 | 9549 | 8488 | 7427 |
| 4 mm | 23873 | 14324 | 11937 | 9549 | 7162 | 6366 | 5570 |
| 5 mm | 19099 | 11459 | 9549 | 7639 | 5730 | 5093 | 4456 |
| 6 mm | 15915 | 9549 | 7958 | 6366 | 4775 | 4244 | 3714 |
| 8 mm | 11937 | 7162 | 5968 | 4775 | 3581 | 3183 | 2785 |
| 10 mm | 9549 | 5730 | 4775 | 3820 | 2865 | 2546 | 2228 |
| 12 mm | 7958 | 4775 | 3979 | 3183 | 2387 | 2122 | 1857 |
| 16 mm | 5968 | 3581 | 2984 | 2387 | 1790 | 1592 | 1393 |
| 20 mm | 4775 | 2865 | 2387 | 1910 | 1432 | 1273 | 1114 |
| 25 mm | 3820 | 2292 | 1910 | 1528 | 1146 | 1019 | 891 |
The diameter is the cutter or drill for milling and drilling, the workpiece for turning. If your machine can't reach the speed, run at its top speed and reduce the feed to match (feed = rpm × flutes × feed per tooth).
Spindle speed (rpm): HSS, inch tools
| Tool | Aluminium (rpm) | Brass and bronze (rpm) | Plastics (rpm) | Mild steel (rpm) | Cast iron (rpm) | Alloy and tool steel (rpm) | Stainless steel (rpm) |
|---|---|---|---|---|---|---|---|
| 1/16 in | 18046 | 12031 | 12031 | 6015 | 4010 | 3008 | 2406 |
| 1/8 in | 9023 | 6015 | 6015 | 3008 | 2005 | 1504 | 1203 |
| 3/16 in | 6015 | 4010 | 4010 | 2005 | 1337 | 1003 | 802 |
| 1/4 in | 4511 | 3008 | 3008 | 1504 | 1003 | 752 | 602 |
| 5/16 in | 3609 | 2406 | 2406 | 1203 | 802 | 602 | 481 |
| 3/8 in | 3008 | 2005 | 2005 | 1003 | 668 | 501 | 401 |
| 1/2 in | 2256 | 1504 | 1504 | 752 | 501 | 376 | 301 |
| 5/8 in | 1805 | 1203 | 1203 | 602 | 401 | 301 | 241 |
| 3/4 in | 1504 | 1003 | 1003 | 501 | 334 | 251 | 201 |
| 1 in | 1128 | 752 | 752 | 376 | 251 | 188 | 150 |
The diameter is the cutter or drill for milling and drilling, the workpiece for turning. If your machine can't reach the speed, run at its top speed and reduce the feed to match (feed = rpm × flutes × feed per tooth).
Spindle speed (rpm): carbide, inch tools
| Tool | Aluminium (rpm) | Brass and bronze (rpm) | Plastics (rpm) | Mild steel (rpm) | Cast iron (rpm) | Alloy and tool steel (rpm) | Stainless steel (rpm) |
|---|---|---|---|---|---|---|---|
| 1/16 in | 60153 | 36092 | 30077 | 24061 | 18046 | 16041 | 14036 |
| 1/8 in | 30077 | 18046 | 15038 | 12031 | 9023 | 8020 | 7018 |
| 3/16 in | 20051 | 12031 | 10026 | 8020 | 6015 | 5347 | 4679 |
| 1/4 in | 15038 | 9023 | 7519 | 6015 | 4511 | 4010 | 3509 |
| 5/16 in | 12031 | 7218 | 6015 | 4812 | 3609 | 3208 | 2807 |
| 3/8 in | 10026 | 6015 | 5013 | 4010 | 3008 | 2673 | 2339 |
| 1/2 in | 7519 | 4511 | 3760 | 3008 | 2256 | 2005 | 1754 |
| 5/8 in | 6015 | 3609 | 3008 | 2406 | 1805 | 1604 | 1404 |
| 3/4 in | 5013 | 3008 | 2506 | 2005 | 1504 | 1337 | 1170 |
| 1 in | 3760 | 2256 | 1880 | 1504 | 1128 | 1003 | 877 |
The diameter is the cutter or drill for milling and drilling, the workpiece for turning. If your machine can't reach the speed, run at its top speed and reduce the feed to match (feed = rpm × flutes × feed per tooth).
About this chart
Starting cutting speeds for common materials, and the spindle speed (rpm) they give for common tool sizes. Choose HSS or carbide, and mm or inch tools, above the chart.
These are safe starting points for general-purpose tools with coolant or cutting fluid: adjust by the sound, the chips and the finish, and use the tool maker's figures where you have them. For a feed rate, or a size not listed, use the speeds and feeds calculator.
How it's worked out:
- rpm = cutting speed (m/min) × 1,000 ÷ (π × diameter in mm), or SFM × 12 ÷ (π × diameter in inches)
- SFM (surface feet per minute) = m/min × 3.281
The cutting speeds are conservative starting points from the low-to-middle of the usual published ranges for uncoated HSS and carbide tooling, the same as the calculator's. Speeds are rounded to the nearest whole rpm; any speed close to these is fine.
Last checked 31 October 2026 · Last rev. 31 October 2026 · 9f55