This page explains the measurement or planning assumption behind the result. When you need the project quantity itself, use Cabinet Run Layout Calculator.
A 3-inch pattern is product-line evidence, not a universal rule
KraftMaid currently describes wall and base cabinet widths that increase in 3 in increments, while also publishing specification books for exact product sizes. That supports a useful default example, but not a claim that every cabinet manufacturer follows the same ladder.
Audit cabinet boxes, not every dimension in the kitchen
The module check belongs to scheduled cabinet nominal widths. Appliance openings, filler strips, scribed panels, wall variation and custom modifications can legitimately produce dimensions that are not multiples of the cabinet increment.
Use the current catalog or quote
Availability changes by line, cabinet type and modification options. A width can align mathematically with the increment and still not be offered for the selected model, so the final schedule must be checked against current manufacturer documentation.
Metric systems need their own module input
Do not convert a 3 in U.S. catalog rule into a supposed metric standard. Enter the actual module or size schedule used by the cabinet system being planned.
Fillers solve fit; they are not “failed modules”
Installation guidance commonly uses filler strips at run ends or walls to close the field-measured gap and provide clearance. Their final width can be scribed to the actual wall and should remain separate from cabinet-box module auditing.
Planning workflow
Choose the cabinet line
Identify the manufacturer/product series before assuming a width pattern.
Read the size schedule
Confirm the nominal widths offered for the exact cabinet type.
Enter the applicable increment
Use 3 in only when the selected line supports that pattern.
Audit each scheduled width
Flag widths that do not align, then verify whether they are custom/special models or data-entry errors.
Keep fillers outside the module check
Use field-measured filler widths to close the run after cabinet boxes are scheduled.
A 3-inch audit catches a likely schedule typo
With a 3 in audit increment, 33, 30, 24, 15 and 9 in all land on whole modules. If one entry is typed as 31 in, the calculator flags that width for review; it does not claim the cabinet is impossible, because a custom or different product line may allow it.
Reference table
| Dimension | Increment audit? | Authority |
|---|---|---|
| Nominal cabinet width | yes | current manufacturer catalog/spec book |
| Appliance opening | no | appliance installation specification |
| Filler / scribe | no | field fit + cabinet installation guidance |
| Custom cabinet width | only if relevant | approved custom order / shop drawing |
Primary references for this planning guidance
These sources document the specific product or industry assumptions called out in this guide. Project specifications and the exact product instructions still take priority.
Supports: KraftMaid describes wall and base cabinet widths in its line as starting at 6 inches and increasing in 3-inch increments, while exact availability varies by cabinet type.
Boundary: This is evidence for one manufacturer product line, not a universal cabinet-width standard. Always use the current catalog or approved schedule for the selected cabinet system.
Supports: KraftMaid describes filler strips as trim used to fill gaps between cabinets and a wall or appliance and notes that fillers can be scribed for irregular walls.
Boundary: Filler location and final width remain product-, design- and field-condition specific. The calculator only preserves an entered filler width in the arithmetic.
Frequently asked questions
Why are many cabinet widths 3 inches apart?
Some cabinet lines organize stock or semi-custom widths in a repeating 3 in ladder. The reason is less important than verifying the current size schedule for the exact product line you plan to buy.
Is a 31-inch cabinet automatically wrong?
Not necessarily. It is off a 3 in module, but custom or different cabinet systems can use nonstandard widths. Treat the flag as a prompt to verify the schedule.
Should a filler be a multiple of 3 inches?
No universal rule requires that. Fillers are often cut or scribed to the actual remaining field gap and clearance need.
Does the calculator choose the best cabinet combination?
No. It audits a schedule you already know. Corners, functionality, storage, appliance landing space and design choices belong in the cabinet design process.
Planning note: Product coverage, yield, package size, installation instructions and project requirements take priority over generic examples. Verify the exact product and project before purchasing.