Calculate Machining Speed and Feed Without Mixing Units
Find spindle RPM, cutting speed, table feed, chip load, feed per revolution, cutting time and geometric removal rate for milling, drilling or turning. Enter current cutting data for the exact tool and material, then let the calculator handle metric and imperial conversions.
Last updated: August 2, 2026- Nine solve modes
- Milling, drilling and turning
- Metric and imperial units
- Optional RPM limit
Machining Speed and Feed Calculator
Choose a process or inverse calculation. Use cutting speed and feed values from the current chart for your exact tool, geometry, coating, work material and cutting conditions.
Enter the required values and select Calculate.
Calculated outputs
All derived rows use unrounded values. The displayed precision never feeds another calculation.
| Quantity | Result | Basis |
|---|---|---|
| — | Calculate to view outputs | — |
Calculation steps
- Choose a process or inverse solve mode.
- The calculator will normalize all active inputs before applying the operation-specific formula.
Results are theoretical starting values. Confirm current cutting data and every rated speed limit before machining.
How to Use This Speed and Feed Calculator
Estimated time: About 2 minutes for a complete entry and result review.
- Choose the process or unknown. Select milling, drilling, turning, RPM, cutting speed, feed rate, chip load, feed per revolution or cutting time.
- Get current cutting data. Use the exact toolmaker chart for your tool, work material, hardness, coating, engagement and coolant condition.
- Enter the effective diameter. Use the cutting diameter at the contact point, which may differ from the nominal tool diameter.
- Choose every unit. Metric and imperial inputs are normalized before a formula is evaluated.
- Enter a rated RPM limit when relevant. Use the lowest applicable limit for the machine, spindle, tool, holder, chuck and workholding.
- Calculate and inspect each output. Review RPM, feed, chip quantity, time or removal rate and the shown substitutions.
- Validate the starting values. Check rigidity, runout, overhang, power, torque, chip evacuation and the manufacturer’s instructions before cutting.
Speed and Feed Formulas
Cutting speed is the tangential speed at the selected diameter. The same physical relationship works in either unit system:
For the metric form, vc is in metres per minute, D is in millimetres and n is revolutions per minute. For inches and surface feet per minute:
Milling table feed uses feed per tooth and the effective number of cutting edges:
Drilling and single-point turning normally use feed per revolution:
Nine Supported Calculation Modes
| Mode | Main formula | Required data |
|---|---|---|
| Milling setup | n = 1000vc/(πD); vf = fznz | Cutting speed, diameter, teeth and chip load |
| Drilling setup | n = 1000vc/(πD); vf = fnn | Cutting speed, drill diameter and feed/rev |
| Turning setup | n = 1000vc/(πD); vf = fnn | Cutting speed, work diameter and feed/rev |
| Spindle speed | n = 1000vc/(πD) | Cutting speed and diameter |
| Cutting speed | vc = πDn/1000 | Diameter and RPM |
| Milling feed | vf = fznz | RPM, teeth and chip load |
| Chip load | fz = vf/(nz) | Table feed, RPM and teeth |
| Feed/revolution | fn = vf/n | Linear feed and RPM |
| Cutting time | T = L/vf | Cutting travel and linear feed |
Milling, Drilling and Turning Use Different Feed Inputs
| Process | Diameter basis | Feed basis | Removal-rate model |
|---|---|---|---|
| Milling | Effective cutter diameter at the cut | Feed per tooth × RPM × effective teeth | Width × axial depth × table feed |
| Drilling | Drill outside diameter | Feed per revolution × RPM | Full circular hole area × penetration feed |
| Turning | Workpiece diameter at the cutting point | Feed per revolution × RPM | Cutting speed × radial depth × feed/rev |
Do not multiply a drill manufacturer’s feed-per-revolution value by the number of drill lips. For milling, do not assume the printed flute count is always the effective cutting-edge count. Follow the toolmaker’s definition for the selected tool and operation.
Worked Example: 10 mm Four-Flute Milling Cutter
Suppose the selected cutting data is 100 m/min with a 10 mm effective diameter, four effective teeth and 0.05 mm/tooth.
- Calculate spindle speed: n = (1000 × 100)/(π × 10) ≈ 3183.098862 RPM.
- Calculate table feed from the unrounded RPM: vf = 0.05 × 3183.098862 × 4.
- The theoretical table feed is approximately 636.6197724 mm/min.
- If the lowest rated limit is 3000 RPM, keep the same entered chip load by using 0.05 × 3000 × 4 = 600 mm/min.
If the cut is 5 mm wide and 2 mm deep, the rectangular milling removal rate at the uncapped feed is approximately 6366.197724 mm³/min, or 6.366197724 cm³/min. This geometric volume does not prove that the spindle has enough power or that chip evacuation is adequate.
RPM Limits and Feed Adjustment
A formula can return a speed above a rated limit. Compare the theoretical RPM with the machine, spindle, cutting tool, holder, chuck and workholding ratings. Use the lowest applicable value. Never treat a calculated RPM as permission to exceed a component rating.
When the entered maximum is lower than the theoretical RPM, the calculator shows both values and recomputes linear feed from the limited RPM. This preserves the entered feed per tooth in milling or feed per revolution in drilling and turning. Silently reducing RPM while leaving the original feed unchanged would raise chip load or feed per revolution.
Constant-surface-speed turning needs extra care. RPM rises as the workpiece diameter decreases, so the control must have a suitable maximum RPM. A single-diameter result describes one point, not the full facing pass.
Effective Diameter, Teeth and Chip Thickness
A square end mill often uses its nominal cutting diameter in a simple peripheral calculation. Ball-nose cutters, round inserts, tapered tools and angled cutting edges can have a smaller effective diameter at the actual depth of cut. Use the toolmaker’s effective-diameter guidance when this difference matters.
Feed per tooth is a programmed feed quantity. It does not always equal maximum chip thickness. Radial engagement, entering angle, tool geometry, runout and chip-thinning effects alter the chip formed by each edge. This calculator applies the basic feed equation and does not add radial chip-thinning, ball-nose or circular-interpolation corrections.
Runout can make one flute remove more material than another. Long overhang, weak workholding or low machine rigidity can also require different starting data. Formula accuracy does not replace setup judgment.
Cutting Time and Material Removal Rate
Cutting time is travel divided by linear feed. Include the intended approach, breakthrough or overtravel in the entered distance. The result excludes rapid moves, spindle acceleration, tool changes, probing, peck retractions, dwell, handling and other cycle events.
The three setup modes show a geometric material removal rate. Milling uses width × depth × table feed. Full-diameter drilling uses circular hole area × penetration feed. Turning uses cutting speed × radial depth × feed per revolution. The drilling model does not fit annular cutters, pilot holes, step drills or boring without an operation-specific area.
Removal volume is not a power, torque, force or tool-strength check. Dense work material also removes more mass for the same volume. Verify spindle capability, holder grip, chip evacuation, coolant delivery, workholding and tool load separately.
Unit Conversion and Display Precision
The calculator normalizes length to millimetres, cutting speed to metres per minute, linear feed to millimetres per minute and time to minutes. One inch equals exactly 25.4 mm, so one SFM equals exactly 0.3048 m/min and one IPM equals exactly 25.4 mm/min.
π is irrational, so RPM and surface-speed results are numerical approximations. The tool retains an unrounded internal value for every derived result and rounds only the displayed text. Choosing more digits changes presentation, not input quality or machining certainty.
Report precision that matches the source data. A broad catalog range or an estimated effective diameter does not support twelve meaningful digits, even when the calculator displays them.
Common Speed and Feed Calculation Mistakes
- Mixing SFM with millimetres. Select each unit explicitly instead of combining an imperial cutting speed with the metric formula.
- Using nominal diameter blindly. Ball-nose, tapered and angled tools may need an effective diameter at the cutting depth.
- Multiplying drilling feed twice. A drill feed listed per revolution already applies to one spindle revolution.
- Rounding RPM before feed. Keep the unrounded theoretical or limited RPM through the feed calculation.
- Capping RPM without changing feed. Recalculate linear feed to preserve the intended chip load or feed per revolution.
- Ignoring rated limits. Tool, holder, chuck, workholding and spindle limits can differ. Use the lowest applicable rating.
- Treating a formula as a recommendation table. Cutting data changes with material condition, tool grade, geometry, coating, engagement, coolant, rigidity and overhang.
- Calling cutting time a cycle time. The simple travel/feed result excludes non-cutting machine and handling events.
Related Engineering Calculators
Use these published tools for connected motion, load and power checks.
Speed and Feed Calculator FAQs
What is the formula for spindle RPM?
With cutting speed in m/min and diameter in mm, RPM equals 1000 times cutting speed divided by π times diameter. With SFM and inches, RPM equals 12 times SFM divided by π times diameter.
How do I calculate milling feed rate?
Multiply feed per tooth by spindle RPM and the effective number of cutting teeth: table feed equals fz × n × z. Keep all length units consistent.
How do I calculate chip load from IPM?
Divide table feed in IPM by RPM and effective teeth. The result is inches per tooth. This programmed feed quantity does not automatically equal maximum chip thickness.
Should drilling use feed per tooth or feed per revolution?
General drilling data is commonly stated per revolution. Do not multiply a catalog feed-per-revolution value by the drill’s two cutting lips unless the manufacturer explicitly defines the value per tooth.
What diameter should I use for turning?
Use the workpiece diameter at the cutting point. During facing or constant-surface-speed work, diameter changes, so one RPM result represents only the entered diameter.
Why does the calculator reduce feed when RPM is limited?
Linear feed depends on RPM. Recalculating feed from the lower RPM preserves the entered feed per tooth for milling or feed per revolution for drilling and turning.
Does this calculator recommend settings by material?
No. Broad material labels do not capture hardness, tool grade, coating, geometry, engagement, coolant, overhang or rigidity. Enter current data for the exact tool and application.
Does feed per tooth equal actual chip thickness?
Not in every cut. Radial engagement, entering angle, runout and tool geometry can change maximum chip thickness. Apply operation-specific corrections from the toolmaker when needed.
What does the cutting-time result include?
It includes only entered cutting travel divided by linear feed. It excludes rapids, acceleration, tool changes, peck retractions, dwell, probing, handling and other cycle events.
Are calculated speeds safe to run directly?
No. Treat them as theoretical starting values. Confirm current toolmaker data and the rated limits of the machine, spindle, tool, holder, chuck and workholding before machining.
Method and Review Basis
- Sandvik Coromant milling formulas, cutting speed, RPM, feed per tooth, table feed and milling removal rate.
- Sandvik Coromant drilling formulas, drilling speed, feed per revolution and full-hole removal rate.
- Sandvik Coromant turning formulas, workpiece-diameter speed, linear feed and turning removal rate.
- Haas Automation metric speeds and feeds formulas, practical milling formula notation.
- Haas Machinist’s CNC Reference Guide, cutting-time and shop-reference context.
- NIST SI length guidance, exact inch-to-millimetre relationship and unit basis.
Machining and engineering disclaimer: Results are theoretical starting values, not safe operating instructions. Verify current cutting data and rated limits for your tool, holder, spindle, machine, chuck or workholding, and material before machining. This page does not assess tool strength, spindle power, torque, vibration, runout, chip evacuation, coolant, workholding or process safety.