Gross Die Per Wafer Calculator
Gross die per wafer is the first number in any wafer cost model. This calculator uses the standard analytic formula so you can compare die sizes, wafer sizes and scribe lanes in seconds, before a stepper map is available.
Your numbers
Nominal wafer diameter.
Die width without scribe lane.
Die height without scribe lane.
Street width added to each die pitch, saw kerf plus guard.
Unusable ring at the wafer edge.
Your results
This is the analytic approximation. A stepper map with real reticle field placement, flat or notch and partial die rules gives the exact count, which can differ by a few percent.
Gross die per wafer vs die width (square die)
Sweeps Die width from 2 to 20, holding your other inputs fixed.
Cost per die from live fab data
Want die counts, starts and sort yield pulled from your ERP or MES automatically? Ask for an expert review of your data sources.
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How to use the calculator
Pick the wafer diameter, then enter the die width and height without the scribe lane. Enter the scribe lane (street) width, which is added to both dimensions to get the die pitch, and the edge exclusion ring that cannot hold good die. The result updates as you type. The chart sweeps square die width from 2 to 20 mm at your other settings, which is a quick way to see how steeply the count falls as die grow. Use the usable diameter output to check your edge exclusion assumption against the process design rules.
The formula behind it
The estimate is DPW = pi x (d/2)^2 / A minus pi x d / sqrt(2A), where d is the usable diameter and A is the die pitch area including scribe lanes. The first term is how many die fit by area. The second term subtracts the partial die lost around the circular edge. The result is rounded down. Area utilization compares die silicon area with the full wafer area, so it also shows the loss from scribe lanes and edge exclusion.
- A = (die width + scribe) x (die height + scribe)
- d = wafer diameter minus twice the edge exclusion
- Exact counts depend on reticle field layout and alignment
Worked example and common mistakes
A 8 mm by 8 mm die on a 300 mm wafer with 0.1 mm scribe and 3 mm edge exclusion gives about 950 gross die and roughly 85 percent area utilization. Typical mistakes: entering die size that already includes the scribe lane, using the notch as an extra exclusion, and treating the gross count as a sellable count. Gross die still needs a yield model before it becomes good die, and non square die or dies stepped in multi project wafers need a real map.
Frequently Asked Questions
How many die fit on a 300 mm wafer?
It depends on die size. A 5 mm square die gives roughly 2,600 gross die, a 10 mm square die roughly 600, with scribe lanes and a few millimeters of edge exclusion. Use the calculator for your exact dimensions.
Is the result exact?
No. It is an analytic estimate that is usually within a few percent of a real stepper map. Reticle field size, shot placement and how partial edge die are handled change the exact count.
What should I enter for scribe lane width?
Use the street width from your design rules, which covers the saw kerf plus guard structures and test keys. Typical values run from tens of microns for plasma or laser dicing up to 100 microns or more for blade dicing.
Does edge exclusion matter?
Yes, more for large die. Edge exclusion of 2 to 5 mm removes a ring where film uniformity and defectivity are worse. Doubling it can cost a noticeable share of die on a 150 mm wafer.
If die counts, lot starts and sort results live in different systems, Netray can build a read-only view over your ERP and MES data so cost per die uses actuals instead of spreadsheet assumptions.
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