Concrete Patch / Resurfacer Calculator
Work out bags, primer and cost for resurfacing a worn slab, patching a spall, or filling a crack.
A thin broom or trowel coat over an existing slab, 1/16 to 1/4 in thick.
1/8 in (0.125) is a common broom-finish resurfacer depth.
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Good fit for a resurfacer coat
Coverage by thickness
Job profile
Resurfacer coverage drops as you apply it thicker \u2014 a 40 lb bag that covers about 150 sq ft at 1/8 inch only covers half that at 1/4 inch. For a 10 \u00d7 10 ft area at 1/8 inch, that is about 1 bag. Deep patches over 1/4 inch use a thicker patch compound calculated by volume instead, and cracks are filled based on their width and depth, not surface area.
Resurfacer coverage by thickness
Figures below assume a standard 40 lb bag and broom finish, before waste.
| Thickness | Coverage per bag | Typical use |
|---|---|---|
| 1/16 in | ~300 sq ft | Very thin cosmetic skim coat |
| 1/8 in | ~150 sq ft | Standard broom-finish overlay |
| 3/16 in | ~100 sq ft | Slightly worn or pitted surfaces |
| 1/4 in | ~75 sq ft | Rougher, more textured surfaces |
Trowel-applied finishes and spray-down textures typically use less material per square foot than a broom finish at the same nominal thickness.
Resurfacer vs patch compound vs crack filler
| Depth range | Best for | Applied by | |
|---|---|---|---|
| Resurfacer | 1/16\u20131/4 in | Renewing a worn but sound surface | Broom, squeegee or trowel |
| Patch compound | 1/4\u20132 in | Spalls, potholes, low spots | Trowel, screed |
| Crack filler | Fills crack profile | Sealing individual cracks | Tube, pour or gun |
How to calculate resurfacer, patch or crack filler
- Resurfacer: coverage per bag scales inversely with thickness \u2014 double the depth, half the coverage.
- Deep patch: treat like a small volume pour \u2014 area \u00d7 depth \u00f7 bag yield in cubic feet.
- Crack filler: multiply crack length by its cross-sectional area (width \u00d7 depth) to get the volume to fill, then divide by a tube’s volume.
- Add waste. 5\u201310% covers mixing loss and trowel waste on all three.
- Add primer. Based on the same surface area, if the product or surface calls for it.
Worked example
A 10 \u00d7 10 ft patio surface, resurfaced at 1/8 inch:
- Area10 \u00d7 10 = 100 sq ft
- Reference coverage150 sq ft/bag at 1/8 in
- Plus 10% waste110 sq ft to cover
- Bags needed110 \u00f7 150 = 0.73 \u2192 1 bag
- Primer (200 sq ft/gal)100 \u00f7 200 = 0.5 \u2192 1 gal
Resurface or replace?
- Resurface ifWear is cosmetic \u2014 surface scaling, minor pitting, discoloration or hairline cracks, with a sound slab underneath.
- Patch ifThere are isolated spalls, potholes or low spots, but the rest of the slab is structurally fine.
- Replace ifThere is significant settling, wide structural cracks, or the base beneath the slab has failed.
- Check drainage firstResurfacing over a slab with a standing-water or ponding problem just delays the same issue.
Surface prep checklist
- Clean thoroughlyPressure wash to remove dirt, oil, loose material and any old sealer.
- Repair major cracks firstFill and let cure before resurfacing over the top.
- Etch or profile dense concreteAcid etching or light grinding helps the new material bond to smooth, dense or sealed surfaces.
- Apply primer if recommendedEspecially on non-porous or previously sealed concrete.
- Work in manageable sectionsResurfacer sets fast \u2014 don’t mix more than you can place and finish before it stiffens.
- Protect from rain and freezingCure time varies by product; check the specific working and cure window.
Common mistakes
- Applying resurfacer too thick in one passIt is formulated as a thin coating, not a structural pour \u2014 going too thick risks cracking and delamination.
- Skipping surface prepDirt, oil or a sealed surface stops the new material bonding, and it will peel or flake off later.
- Resurfacing over a structural problemA cosmetic fix over settling or a failed base only hides the issue temporarily.
- Underestimating coverage drop at thicker depthsDoubling the thickness does not just use a bit more material \u2014 it roughly halves the coverage per bag.
- Ignoring crack width when sizing fillerA wider or deeper crack needs proportionally more filler \u2014 length alone is not enough to size the job.
- Mixing more than you can placeMost resurfacer and patch products set faster than standard concrete \u2014 work in batches you can finish in time.
What this calculator assumes
Adjust your result if your product differs from these.
- Resurfacer reference coverage of 150 sq ft per 40 lb bag at 1/8 in, broom finish
- Patch compound yield of about 0.33 cu ft per 40 lb bag
- Bonding primer coverage of about 200 sq ft per gallon
- Crack filler reference of 10 linear ft per tube at a 1/4 x 1/4 in crack profile, scaled by cross-sectional area
- Coverage figures vary meaningfully by brand and finish technique \u2014 always check your specific product’s label
- Prices are whatever you enter; they are not live market rates
Common questions
How thick can you pour concrete resurfacer?
Standard concrete resurfacer is designed for thin overlays, typically 1/16 to 1/4 inch. Going much thicker in one pass risks cracking and poor bonding, since it’s formulated as a surface coating, not a structural pour.
How much area does a bag of concrete resurfacer cover?
A 40 lb bag typically covers about 150 sq ft at 1/8 inch thick with a broom finish. Coverage drops significantly at thicker applications or with a trowel finish.
Do I need primer before resurfacing concrete?
Most manufacturers recommend a bonding primer or a damp surface before applying resurfacer, especially on smooth, dense or previously sealed concrete, to help the new layer bond properly.
What is the difference between resurfacer and patch compound?
Resurfacer is a thin, broom or trowel applied coating for renewing a worn but structurally sound surface. Patch compound is thicker and used to fill spalls, potholes or low spots up to about 2 inches deep.
How do you fix a crack in concrete?
Clean the crack of debris and loose material, then fill it with a flexible crack sealant or filler sized to the crack’s width and depth. Hairline cracks may only need a surface sealant, while wider cracks need a proper filler product.
Should I resurface or replace a concrete slab?
Resurfacing works well for cosmetic wear, minor surface scaling and small cracks on a slab that’s otherwise structurally sound. Replace the slab if there’s significant settling, large structural cracks, or the base beneath it has failed.
How long does concrete resurfacer take to cure?
Light foot traffic is usually fine after 4 to 6 hours, vehicle traffic after about 24 hours, and full cure takes around 7 days depending on temperature and humidity.
Can I resurface concrete myself?
Yes for small to medium areas. Surface prep \u2014 cleaning, pressure washing and possibly acid etching or priming \u2014 matters more to the outcome than the resurfacing product itself.
How much does concrete crack filler cover?
Coverage depends on the crack’s width and depth. A typical 10 oz tube covers roughly 10 linear feet of a 1/4 inch wide, 1/4 inch deep crack; wider or deeper cracks need proportionally more.
What causes concrete to need resurfacing?
Surface scaling from freeze-thaw cycles, general wear, minor spalling, discoloration and small non-structural cracks are the most common reasons a slab is resurfaced rather than replaced.
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Project
| Job type | — |
| Dimensions | — |
| Thickness / profile | — |
| Waste allowance | — |
Shopping list
| Bags / tubes | — |
| Primer | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Coverage figures are typical values \u2014 always confirm with your specific product’s label before ordering.