How do you calculate a breakage reserve?

Multiply slabs handled by replacement cost per slab by the breakage rate, then add claims handling. For 200 slabs at $850 each with a 3% breakage rate plus $500 handling, that is 200 x 850 x 0.03 + 500 = $5,600.

What is a normal slab breakage rate?

Well-run shops run 1-3% across granite and quartz. Fragile quartzite, marble, and large-format porcelain can hit 5-8%. The example uses 3%, a realistic blended figure for a mixed-material shop.

What is the reserve cost per slab?

Total reserve divided by slabs handled. Here $5,600 over 200 slabs is $28 per slab, which is the breakage allowance you should embed in each slab's landed cost.

Does the reserve cover the labor lost on a broken slab?

Only if you build it in. The variable $5,100 covers replacement material; the fixed $500 claims-handling piece covers admin and reorder. Rework labor and a rush reorder freight should be added if they are significant.

Breakage reserve vs insurance deductible — how do they relate?

The reserve funds routine, expected breakage that never rises to a claim. Insurance covers catastrophic events above your deductible. Most shop breakage falls under the deductible, so the reserve is what actually pays for it.

How often should I update the breakage rate?

Recalculate every quarter using actual broken-slab counts. A rate drifting from 3% toward 5% signals a handling, rigging, or transport problem worth investigating before it grows.

Stone, Countertops & Engineered Surfaces calculator

Breakage reserve Calculator

Breakage Reserve is the pool of money a stone shop sets aside to cover slabs that crack, chip, or shatter during handling, fabrication, transport, and install. Owners, estimators, and insurers use it because natural stone and even sintered surfaces fail at a predictable rate, and a single broken quartzite slab can wipe out the margin on several jobs. The reserve converts a historical breakage percentage into a real dollar figure so it can be baked into pricing instead of hitting the P&L as a surprise. It also adds a fixed claims-handling cost for the admin, reorder, and rescheduling burden every breakage event carries beyond the slab itself.

What this calculator does

Estimates a breakage reserve covering slabs lost to cracking or chipping during handling, transport, and installation.
A fabrication-shop owner setting aside a reserve against slab breakage on a large project.
It computes the total breakage reserve, the reserve cost per slab, and the split between variable breakage exposure and fixed claims-handling overhead.

Formula used

Breakage reserve $ = slabs handled x replacement cost x breakage rate% + claims handling
Reserve per slab = total reserve / slabs handled

Inputs explained

Slabs handled:
Replacement cost per slab:
Slab breakage rate:
Claims handling cost:

How to use the result

Use it when pricing in a breakage allowance, setting an annual reserve budget, or evaluating whether a fragile material like quartzite justifies a surcharge.
It uses a flat average breakage rate; thin material, long overhangs, and large-format porcelain break far above the average and need their own rate.

Common questions

How do you calculate a breakage reserve? Multiply slabs handled by replacement cost per slab by the breakage rate, then add claims handling. For 200 slabs at $850 each with a 3% breakage rate plus $500 handling, that is 200 x 850 x 0.03 + 500 = $5,600.
What is a normal slab breakage rate? Well-run shops run 1-3% across granite and quartz. Fragile quartzite, marble, and large-format porcelain can hit 5-8%. The example uses 3%, a realistic blended figure for a mixed-material shop.
What is the reserve cost per slab? Total reserve divided by slabs handled. Here $5,600 over 200 slabs is $28 per slab, which is the breakage allowance you should embed in each slab's landed cost.
Does the reserve cover the labor lost on a broken slab? Only if you build it in. The variable $5,100 covers replacement material; the fixed $500 claims-handling piece covers admin and reorder. Rework labor and a rush reorder freight should be added if they are significant.
Breakage reserve vs insurance deductible — how do they relate? The reserve funds routine, expected breakage that never rises to a claim. Insurance covers catastrophic events above your deductible. Most shop breakage falls under the deductible, so the reserve is what actually pays for it.

Last reviewed 2026-05-12.