Bar Stock Yield and Material Cost per Part Calculator
Material is often the largest cost in a turned part, and the quoted price per bar rarely equals the cost per part. This calculator accounts for cutoff width, bar-end loss and scrap so the material line in a quote is right.
Your numbers
Bar-feeder stub, chuck grip and facing allowance.
Parting tool or saw kerf.
Your results
Parts per bar vs part length
Sweeps Part length including facing stock from 20 to 100, holding your other inputs fixed.
Compare routing material to actual consumption
Optional: find parts where ERP material quantities are off.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the bar length, the unusable end per bar, the part length including any facing stock and the cutoff width. Add the bar price, the quantity you must ship and a scrap allowance. You get parts per bar, bars to buy, yield and material cost per good part. The chart shows how parts per bar steps down as the part gets longer, which helps when a small change in length saves a whole part per bar.
The formula
A bar yields n parts when n x part length + (n - 1) x cutoff width + end loss fits in the bar. Solving for n gives floor((bar - end loss + kerf) / (part + kerf)). Bars needed is started quantity divided by parts per bar, rounded up. Yield is the share of bar length that becomes parts, not counting the cutoff or remnants.
- Facing stock is part of the part length for this purpose
- Use the real bar-feeder remnant for your machine
- Round bars up; partial bars are still bought whole
Common mistakes
Dividing bar length by part length ignores the cutoff and over-promises yield. Forgetting bar-end remnants is the next most common error, and it hurts most on short bars. Buying standard 12 foot bars sawn to length can change parts per bar entirely, so test both stock lengths. Record the result in the routing material quantity so the ERP backflushes the right amount.
Frequently Asked Questions
Why is there a kerf term in the numerator?
Because the last part has no cut after it. With n parts you have n minus 1 cutoffs, so adding one kerf to the available length makes the floor division exact.
Does this work for sawed blanks?
Yes. Enter saw kerf as the cutoff width and set end loss to the offcut you cannot use. The formula is identical.
How should I treat bar diameter?
Length is the only geometry here. Cost per bar already reflects diameter and grade, so use the bar price from your supplier for that size.
What scrap allowance should I use?
Use your actual first-article and in-process scrap for similar parts. Short runs with tight tolerances usually need more allowance than long repeat runs.
Netray can compare the material quantity on your ERP routings with what the floor actually consumes, and flag parts where they differ.
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