Concrete Grinding Cost Calculator

It calculates your direct grinding cost per m² / sqft — diamond tooling, fuel for the generator or LPG burner, generator hire (if you hire instead of own), equipment depreciation, routine servicing, and dust extraction consumables (HEPA filters, pre-filters, vacuum bags). These are the variable costs that scale directly with how much grinding the machine does, so they belong in the rate you charge per m² / sqft.

It deliberately leaves out labor, vehicle and trailer costs, mobilisation, water and slurry disposal if wet grinding, profit margin, and overheads (insurance, accounting, etc.). Those costs vary so much by region and business size that mixing them in would produce a misleading rate.

The correct workflow is: use this calculator to get a clean direct cost per m² or sqft, add your labor rate × time (use the Grinding Time Calculator for hours), add a fair share of overheads, then apply your target margin in the Profit Margin Calculator. The number you charge per m² / sqft on a quote is the sum of all those layers — not just the figure from this calculator.

When you don't own a generator and hire one for the day, switch the Generator toggle to Hired. You enter the day rate from the hire company, optionally a one-off delivery fee, and whether fuel is included.

The maths: (Hire Rate + Delivery) ÷ 8 hrs = hire cost per hour, which is then divided by your production rate to give you $/m² or $/sqft. The 8-hour day is a standard hire-day assumption — the day rate is a fixed charge regardless of how many hours you actually grind, but the calculator has to spread it across some duration to express it as $/area. On a full-day grind the figure is accurate; on a half-day grind the real per-area cost is higher because the same day rate covers less area, so treat the figure as conservative on short jobs.

Wet hire (fuel bundled into the day rate) hides the burn-rate / fuel-price fields. Dry hire keeps them — you pay for fuel on top of the day rate. When Hired is selected, the Generator Depreciation and Generator Servicing sections disappear because those costs sit with the hire company, not you.

Yes. HEPA filters, pre-filters, and vacuum bags are a real direct cost that scales with grinding hours, in the same shape as routine servicing. A full set of HEPA + pre-filter + bags usually runs $150–300 and needs replacing every 150–250 run-time hours on commercial-grade vacs. Skipping it under-costs every job by a small but consistent amount.

Fold the total cost of one complete consumable set into Consumables Cost, and the run-time hours between full replacement into Replacement Interval. Vacuum depreciation (the $4–8k purchase price of the extractor itself) is not modelled here — fold that into your overhead allocation unless you want to add a second depreciation line in Equipment Depreciation.

Diamond lifespan is the total m² or sqft a complete set of diamonds will grind before the segments are worn down to the steel and need replacing.

Manufacturers publish ballpark figures — typically 15,000–30,000 sqft (1,400–2,800 m²) for medium-bond metal-bonded diamonds on average-hardness concrete. Hybrids and PCDs have different lifespans entirely. The honest way to get your real number is to track a set from new to worn-out across two or three jobs and divide total area by sets used.

Key factors that move the number: concrete hardness (hard slabs can halve the life), grit (lower grits wear faster), bond match (wrong bond can destroy a set in a single job), and operator technique (overlapping passes and excessive head pressure shorten life).

For on-site grinding without grid power, propane is often cheaper to run than an electric grinder powered by a generator. A typical propane planetary burns ~1 gal/hr at $3.50/gal ≈ $3.50/hr. The same job on an electric grinder needs a diesel/petrol generator (typically 15–25 kVA) burning 2–3 gal/hr at $4.50–5/gal ≈ $9–15/hr — diesel generators are roughly 25–35% efficient at turning fuel into electricity, so you pay the conversion penalty in fuel.

Grid-tied electric is a different story — if you can plug into a building's 3-phase supply, electric is dramatically cheaper. But on most slab-prep jobs (new builds, no power, residential, warehouses) that isn't available, and a generator is the only way to run an electric grinder.

This calculator models the fuel cost directly. If you rent or transport a generator (or transformer) separately, fold that into your overhead allocation, not the per-hour fuel inputs.

Power cost as $/m² is only as accurate as your production rate input. The formula is (burn rate × fuel price) ÷ (production rate), so a 20% error in production rate moves the power cost by 20%.

Use the production rate that matches the prep level you're costing — light prep at 30 m²/hr is very different from heavy coating removal at 8 m²/hr. The Grinding Time Calculator can help you set realistic rates by pass type. Most contractors find power cost lands between 10% and 40% of total direct grinding cost (propane lower, generator-powered electric higher) — if your number is way outside that range, double-check your production rate or burn rate.

The calculator works in run-time hours — divide the purchase price by the total hours you realistically expect from the machine, then it converts to $/m² or $/sqft using your production rate.

Because the input is the machine's full purchase price spread across its whole life, this line recovers the entire cost of the grinder over the hours you run it — by the time it's worn out, the depreciation you've charged into jobs has paid for its replacement. It is not "valued in" anywhere else, so if you leave it out you're quietly funding the next machine out of your own pocket.

Industry averages suggest a quality propane or electric concrete grinder will give 3,000–8,000 run-time hours of useful life with proper maintenance. A heavy planetary built for daily commercial work sits at the top of that range; a lighter single-head used hard sits at the bottom. Many manufacturers publish an expected service-hour figure for their machines — start there and adjust based on how the machine is actually used.

If you prefer the accounting approach, you can instead divide annual depreciation (purchase price ÷ years to write off) by annual run-time hours. Both methods land at a similar $/hr figure if your assumptions are reasonable. The calculator then divides that by production rate to give $/area.

If you bought the machine on finance, a loan, or a lease, the interest is a real cost of owning it that straight-line depreciation doesn't capture — depreciation only spreads the purchase price, not the cost of the money used to buy it.

The simple way to fold it in: take the total interest you'll pay over the finance term, add it to the purchase price, and enter that combined figure as the amount to depreciate over the machine's run-time hours. For example, an $18,000 grinder with $3,000 of total interest behaves like a $21,000 machine for costing purposes — the depreciation line then recovers both.

Even if you paid cash there is an opportunity cost, because that money could have earned a return elsewhere, so some contractors add a few percent a year on the same basis. Keep it simple: the aim is that your per-area rate quietly recovers both the machine and the cost of financing it, so replacing it is self-funded.

Yes — use a weighted average that reflects the prep level you're costing. If a job is mostly medium grind with some heavy edge work, your effective rate sits between the two. The Grinding Time Calculator can help by letting you set pass type and number of passes for a realistic time estimate. For a quick check, time yourself across a representative 100 sqft / 10 m² area on the actual slab — that's usually more accurate than any spec sheet.

Yes for the calculation itself — diamonds, generator fuel (or LPG), and depreciation still apply. But wet grinding adds slurry disposal and water cost that this calculator doesn't cover. If you wet grind, add a per-job slurry disposal line to your final estimate. Diamond lifespan in wet grinding is also typically longer than dry, so use a separate lifespan figure if you do both.

Typical direct grinding cost (the four components in this calculator) ranges from about $0.08 to $0.28 per sqft ($0.85 to $3.00 per m²), depending on concrete hardness, prep level, and machine size.

If your number is well below that, you may be missing depreciation, underestimating service intervals, or overestimating diamond life. If well above, your production rate is probably too low for the diamond grit you're modelling, or your diamond cost is high relative to lifespan — check the bond/grit match against the slab.

The total cost of one scheduled service — parts, consumables, and labor. That typically means oil and gear-oil changes, air and fuel filters, belts, spark plugs, planetary head plates or skirts, vacuum filters that get replaced on a schedule, and either your own labor time or the mechanic's invoice if you outsource the work.

Do NOT include diamond replacement here (it has its own input) or repairs caused by damage and breakdowns. Damage repair is bad-luck cost, not routine cost — bundle that separately into your overhead allocation. Service Interval is the typical run-time hours between those scheduled services for your machine — check the manufacturer manual; most planetary grinders are spec'd at 100–250 hrs.