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? →

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estimated slabs
    This is a rough planning estimate, not a bid-ready count. It divides total area by an assumed usable area per slab — it doesn't know your real piece shapes, slab kerf, or how individual pieces actually pack together, so two jobs with the same total area can need a different number of real slabs. For a per-unit count, use the free estimator on your own piece sizes, or the full app for a validated, DXF-based count. Verify any number from this page before it goes into a bid.

    How this number is calculated

    Three inputs go into the estimate:

    1. Total countertop area. Either entered directly in square feet, or as piece count × an average piece size — both reduce to the same total.
    2. 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.
    3. 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.
    Slabs needed = ceil(total area ÷ (slab area × yield%)) — always rounded up, never down, so the estimate leans toward more slabs rather than fewer.

    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.

    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.

    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.

    Try it now → See pricing