Countertop slab calculator: how many slabs do you need?
Estimated slabs = total countertop area ÷ (slab area × your yield assumption), rounded up. Enter your numbers below for an instant planning estimate — computed right here in your browser, nothing uploaded, no sign-up.
How much of each slab ends up as usable countertop after cutting waste and offcuts. 75–85% is typical for a mixed multifamily job; a lower number is the more conservative planning assumption. What's a good yield number? →
How this number is calculated
Three inputs go into the estimate:
- Total countertop area. Either entered directly in square feet, or as piece count × an average piece size — both reduce to the same total.
- Slab area. Slab width × length, converted to square feet. 130″ × 78″ is a common slab size and this calculator's default; enter your own if your supplier runs a different size — typical dimensions by material are in the slab sizes reference.
- Yield assumption. The percentage of each slab's area you expect to use after cutting waste, kerf, and offcuts — folded into one number here rather than modeled separately, which is what makes this a planning tool and not a nest.
Want a count based on your actual piece sizes instead of an area-and-yield assumption? The free web estimator packs real piece dimensions onto slabs and returns a slab count and yield percentage for up to three unit types. For a full job — real DXFs, up to 18 unit types, an independent validator, and an AlphaCAM-ready export — see pricing for the free trial.
How many slabs for a whole apartment building?
A multifamily job isn't one countertop area — it's a unit mix, and the slab count follows from how those unit types nest, not from square footage alone. Two jobs with the same total area can need a different number of slabs depending on piece shapes and how tightly they pack. That's why the honest way to size a building is per unit type, not one lump area.
A worked example from a real, anonymized job: Ridgeline Flats — 108 units across 3 unit types. Nested with StoneNest's validator at the shipped 0.133″ kerf default, it came to 132 slabs at 81.6% yield. To rough that in on this page, you'd take the job's total countertop area and divide by a slab at a yield assumption in the 75–85% range — but the 132 is the count an actual nest produced, and it's the number you'd bid against.
More on the batch approach real shops use: multifamily countertop estimating and how many slabs your job needs.
FAQ
How is the slab count on this page calculated?
Estimated slabs = total countertop area ÷ (slab area × your yield assumption), rounded up. Slab area comes from the width and length you enter (130″ × 78″ by default — a common slab size); the yield percentage estimates how much of that area ends up as usable countertop after cutting waste. The result is always rounded up, not down, so the estimate errs toward more slabs rather than fewer.
What yield percentage should I use?
75% is the default here and a conservative starting point. For a mixed multifamily job, 75–85% is a reasonable range depending on piece mix and how much of the job is irregular or oversized pieces — see the slab yield guide for what moves that number up or down. When in doubt, use a lower yield number; it produces a higher, safer slab estimate.
Is this the same as StoneNest's full nesting engine?
No. This calculator does simple area-and-yield arithmetic — it doesn't know your actual piece shapes, slab kerf, or how individual pieces pack together, so it can't refuse an invalid layout the way a real nest can. For a per-unit slab count computed from real piece sizes, use the free web estimator; for a full DXF-based nest with an independent validator, use the desktop app.
Does this calculator upload my numbers anywhere?
No. It runs entirely in your browser — nothing you type here is sent to a server. That matches how the free web estimator and the desktop app both work.
How many slabs do I need for a 100-unit apartment building?
It depends on the unit mix, not just the unit count — a studio and a three-bed carry very different countertop area, so start from your unit types, not one lump number. As a reference point, a real 108-unit job across 3 unit types (Ridgeline Flats) nested to 132 slabs at 81.6% yield with a 0.133″ kerf. For your own job, put the unit mix through the free web estimator for a per-mix count, then run the full building — every unit type, validated and exportable — on the desktop app.
Can this size a 50-unit or 200-unit multifamily job?
Use it as a first-pass check at any scale: enter the job's total countertop area and a 75–85% yield assumption for a rough slab count. But a bid-ready count for a whole building comes from nesting the actual unit DXFs — the multifamily estimating guide walks through how shops batch a job by unit type rather than sizing it from one area figure.
Get a slab count from your real piece sizes
This page is a planning estimate. Try the free web estimator with your own unit counts, or start the 7-day free trial for full DXF import, export, and the validator gate.