A reamer speed and feed calculator is most useful when the user already has reamer-specific cutting data and needs to translate it into CNC values. Reaming is a finishing process, so hole allowance, alignment, runout and tool condition deserve as much attention as the numerical RPM and feed.
The calculator gives RPM from cutting speed and reamer diameter, then converts feed per revolution to linear feed. That matches the way many reaming references are expressed and makes the output easy to compare with a CNC block or setup sheet.
Start with the basic calculation, then go deeper
Run the smallest calculation that matches the job. Use the advanced version when additional process or machine variables need to be checked.
Quick Reaming Calculator
Run the common calculation for this machining task.
Spindle Speed
Enter the values you know. The result is calculated in your browser.
Calculation only. Verify toolmaker data, material grade, engagement, machine limits, workholding and actual cutting conditions before production.
Advanced Reaming Calculation
Add the main process variables and machine checks for a fuller calculation.
Feed Per Rev
Enter the values you know. The result is calculated in your browser.
Calculation only. Verify toolmaker data, material grade, engagement, machine limits, workholding and actual cutting conditions before production.
What this reamer speed and feed calculator calculates
Enter the reamer diameter, selected cutting speed, feed per revolution, RPM and programmed feed. Record the starting hole diameter and target final size as well. A reamer can only perform predictably if the starting hole leaves the intended amount of material for the finishing operation.
Formulas and unit handling
Use the standard RPM relationship for the reamer diameter, then feed = RPM × feed/rev. The formulas are simple; the finishing process is not. Reamer geometry and material compatibility control the source cutting data and therefore determine the input range that should be used.
RPM = (1000 × Vc) ÷ (π × D).Use the source unit shown in your tooling reference before converting.Feed rate = RPM × feed per revolution.Use the source unit shown in your tooling reference before converting.Feed/rev = feed rate ÷ RPM.Use the source unit shown in your tooling reference before converting.Final size depends on allowance, tool condition, runout and alignment as well as cutting data.Use the source unit shown in your tooling reference before converting.Step-by-step workflow
Technical context for this search
Reamer calculations should start with the reamer’s actual cutting diameter and a manufacturer-approved speed/feed range. The pre-drilled hole is part of the process, but it is not the diameter used in the RPM formula. This distinction prevents a common mistake where the drill size is accidentally carried into the reamer calculation.
The feed-per-rev value is especially important because reaming is a finishing operation. Excessively low feed can promote rubbing, while excessive feed can raise load and affect finish. Neither a generic drilling chart nor a general milling chip-load table should be used to choose the reamer feed unless the toolmaker explicitly provides the equivalence. The page therefore emphasizes source-data matching before calculation.
Hole allowance and alignment can dominate dimensional results. Measure the pilot hole, inspect runout and confirm the reamer enters concentrically. A good RPM/feed pair cannot compensate for a pre-hole that is outside the intended allowance or a spindle/tool interface that is not aligned.
For troubleshooting, compare first-hole size and finish with the source condition and the recorded allowance. If holes grow over a batch, inspect tool wear and runout before making a large cutting-condition change. A measured history makes it possible to distinguish a cutting-data issue from a tooling or machine issue.
Calculation audit checklist
| Check | What to verify |
|---|---|
| Operation check | Confirm that the job is actually reaming before entering values. The calculator pair on this page was selected for the reamer speed and feed calculator search intent, so switching to another operation may require a different feed convention. |
| Source check | Use the exact tooling or process reference behind reamer speed and feed calculator. Record the tool or process identifier, material and source units before converting anything; the site calculates from supplied values rather than selecting proprietary cutting data. |
| Input check | Verify the primary inputs used by the spindle-speed and feed-per-rev calculators. A field can be numerically valid while still being the wrong variable for the operation, especially when moving between chip load, feed/rev, feed rate and surface speed. |
| Unit check | Keep metric and imperial values separated through the calculation. Recheck diameter, cutting speed and feed units on the Reamer Speed and Feed Calculator page before accepting the result, and only round after the relationship has been verified. |
| Machine check | Compare the theoretical output with machine spindle, feed, travel and process limits. A calculated value is not a machine capability statement, and a controller limit can make the effective cutting condition different from the selected target. |
| Tool/setup check | Review tool condition, runout, overhang, workholding and coolant or lubrication where relevant to reaming. These variables are outside the arithmetic model but can dominate the actual cutting result. |
| First-cut check | Treat the first part or first hole as a validation event. Record chips, sound, load, finish and dimensional result alongside the calculated RPM/feed so later changes can be traced to evidence rather than memory. |
| Recordkeeping check | For repeat work, save the source reference, selected inputs, calculated values and final programmed values together. The Reamer Speed and Feed Calculator calculation then becomes a reproducible setup record instead of a one-time online number. |
Worked example
With a 10 mm reamer at 25 m/min and 0.15 mm/rev, the calculator gives about 796 RPM and 119 mm/min. The number is a conversion of selected inputs; the actual suitability depends on the reamer series and workpiece material.
Practical setup checks
Good reaming results usually begin with a good pilot hole. If the starting hole is tapered, misaligned or too small, a correct speed/feed calculation cannot repair the geometry. Measure the pilot hole where required, control runout and keep the reamer aligned with the spindle and workpiece.
Common mistakes
- Treating reaming like drilling.
- Ignoring allowance.
- Using feed values from another reamer series.
- Skipping runout checks.
- Not measuring the first hole.
Troubleshooting the calculated condition
For oversize or tapered holes, inspect alignment, runout and starting-hole quality. For rough finish, inspect feed, coolant and tool condition. If torque increases, verify allowance and material compatibility before reducing speed blindly.
How to cross-check tool data
Use the reamer manufacturer’s table for the exact tool and material. The calculator exists to turn those values into consistent CNC RPM and feed values and to provide a visible formula trace.
Frequently asked questions
Does reamer RPM use the reamer diameter?
Yes. The rotating diameter in the speed formula is the reamer cutting diameter.
Is reamer feed usually per revolution?
Yes. Feed per revolution is a common reference format for reaming conditions.
What causes oversize holes even when the formula is correct?
Runout, alignment, starting-hole condition, tool wear, allowance and material behavior can all change final size.
Should reaming speed be taken from a drilling chart?
No. Use the reamer manufacturer’s own data for the actual tool.
This page calculates relationships from the values supplied by the user. It does not inspect the machine, tool condition, workholding or material state. Verify production cutting values against the exact tooling reference and the actual setup before running the cut.