Loan Countertop Estimator
Countertops are quoted per square foot but bought by the slab — and the gap between those two numbers is where budgets wobble. Measure the runs, get square feet, slab count and an installed cost at your rate.
Standard counter depth is 25.5 in (24-in cabinets plus a small overhang); islands run 36–42 in deep. A full granite or quartz slab is roughly 110–120 × 70–76 in, but seams, sink cutouts and unusable edges bring the honestly usable area to about 40–50 sq ft — 45 is the planning figure fabricators use.
How it works
Square footage = Σ (length × depth) ÷ 144 across both sections. Slab count = area ÷ usable sq ft per slab, rounded up — because a slab is bought whole even when the last piece is a windowsill. Cost = area × your installed rate, which for stone and quartz typically bundles templating, fabrication, edging and installation; the per-sq-ft rate, not the slab count, drives the quote in most shops, but the slab count drives it in remnant yards and whole-slab pricing, so the estimator shows both.
Formula & worked example
Formula: Square feet = (length₁ × depth₁ + length₂ × depth₂) ÷ 144, in inches. Slabs = area ÷ usable sq ft per slab, rounded up. Cost = area × installed price per sq ft.
Worked example: A 96-in run with a 60-in return, both 25.5 in deep: (2,448 + 1,530) ÷ 144 = 27.62 sq ft — 1 slab at 45 usable sq ft, and $1,795.62 installed at $65 per sq ft.
When to use this
- Budgeting a stone or quartz counter replacement before fabricator quotes.
- Deciding between remnant-yard pricing (per slab) and shop pricing (per sq ft).
- Sizing an island addition to an existing kitchen.
- Checking a fabricator's square-footage figure against your own tape measurements.
How to use it, step by step
- Measure each run's length and depth in inches, overhangs included.
- Enter the second run or island with its own depth (islands run deeper).
- Set usable slab size: 45 sq ft is the honest planning figure.
- Enter your quoted or researched per-sq-ft installed rate.
- Compare the slab count against any whole-slab quote you receive.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Run lengths & depths | Counter sections in inches | Runs 48–144 in, depth 25.5 in |
| Usable slab size | Sq ft honestly usable per slab after cutouts | 40–50 sq ft, 45 typical |
| Price per sq ft | Installed rate incl. fabrication | $55–$100 stone/quartz |
Another worked example
A galley plus island: 120-in run at standard depth, and a 72 × 39 in island. Areas: 21.25 + 19.50 = 40.75 sq ft. At a conservative 40 sq ft usable per slab that is 2 slabs, and at a premium $85 per sq ft the installed estimate is $3,463.75 — the island's depth is what pushes it over one slab.
Frequently asked questions
How many square feet is a standard kitchen counter?
The default here — a 96-in run plus a 60-in return, both 25.5 in deep — is 27.62 sq ft: one slab at 45 usable sq ft, and $1,795.63 installed at $65 per sq ft. Most kitchens land between 25 and 45 sq ft.
How many slabs do I need?
Divide your square footage by about 45 usable sq ft per slab and round up. The example in the detail section — 40.75 sq ft including an island — fits one 45-sq-ft slab on paper, but at a 40 sq ft usable figure it takes 2: layout and vein direction, not raw area, often make the call.
What does countertop cost per square foot installed?
Laminate $20–$40, butcher block $40–$70, granite and quartz $55–$100+, marble and exotics beyond. The rate usually includes templating, fabrication and install; sinks, faucets and backsplashes are separate lines.
Is an island measured differently?
Only by depth: islands run 36–42 in deep instead of 25.5, so the same 72-in length yields 20.25 sq ft at island depth against 12.75 at counter depth. The estimator's second section takes its own depth for exactly this reason.
Do fabricators charge for the sink cutout area?
Generally yes — quotes are written on the gross square footage of the pieces fabricated, cutouts included. Ask explicitly; a shop that deducts cutouts is offering a real discount worth comparing.
🍳 Counters inside a whole kitchen remodel?
The Kitchen Remodel Estimator budgets the full job by tier — and shows the countertop share of the total.
What is the standard countertop depth?
25.5 in for wall runs — 24-in base cabinets, a ¾-in door face and a small overhang. Bathroom vanities run 21–22.5 in deep. Islands and peninsulas are the exception, at 36–42 in with seating overhangs of 12–15 in on one side.
Are quartz and granite priced the same way?
Both price per installed sq ft in most shops, with quartz often more consistent (engineered pricing) and granite spread wider (common stones cheap, exotics dear). Remnant yards price per slab or per remnant piece — where the slab count in this estimator becomes the deciding number.