Concrete Crack Repair Calculator

Enter crack length, width, and depth to calculate filler volume and how many cartridges to order.

Last updated July 16, 2026

Calculate Your Crack Filler Volume and Cartridges

Measure a crack at its widest and deepest, add the length, and the tool works out how much filler or injection resin it'll swallow. Results come in mL, fluid ounces, and the number of standard cartridges or bulk units to order.

Crack Dimensions

Total length of crack to fill. Add up multiple cracks if you're doing several.
Measure at the widest point of the crack
Estimate depth — use a nail or probe if unsure
0%5%10%15%20%25%30%
Result Units
Enter crack dimensions to calculate.

How the Concrete Crack Repair Calculator Works

  1. Measure the total length of the crack in feet or meters
  2. Measure the crack width at its widest point — use mm or inches
  3. Estimate the crack depth — probe with a nail or thin wire if the depth is not visible
  4. Adjust the waste allowance to account for surface absorption, taper, and voids
  5. Read the volume result and select the cartridge size that matches your product

Examples

Scenario10 ft hairline crack — 2 mm wide, 10 mm deepInput10 ft · 2 mm wide · 10 mm deep · 15% wasteResult72 mL · 2.4 fl oz · 1 × 300 mL cartridge
Scenario6 m structural crack — 5 mm wide, 30 mm deepInput6 m · 5 mm wide · 30 mm deep · 15% wasteResult1,035 mL · 35.0 fl oz · 2 × 600 mL cartridges
Scenario20 ft control joint — 8 mm wide, 50 mm deepInput20 ft · 8 mm wide · 50 mm deep · 15% wasteResult2,819 mL · 95.3 fl oz · 1 × 1 gallon unit

Frequently Asked Questions

What type of product should I use for crack repair?

It depends on the gap. A dormant crack that needs bonding back together takes a rigid, low viscosity epoxy, injected or gravity fed, and only once whatever caused the crack has stopped. A sawn joint with hard wheels crossing it takes a semi-rigid epoxy or polyurea joint filler, which holds the joint edges up but does not stretch, so it separates as the joint opens. A joint that moves and carries no hard wheels takes a flexible sealant over a backer rod. A crack that is still moving is not filled shut by anything: it is treated as a joint.

How do I measure crack depth?

Insert a thin wire, nail, or depth gauge into the crack and mark where the surface is. Measure the marked length. For very deep or through cracks, assume the full slab depth (typically 4–6 inches for residential slabs). If you cannot probe the depth, use 20 mm as a conservative estimate for surface cracks.

Why is there a waste allowance?

Cracks are rarely uniform — they taper, branch, and have internal voids that consume more material than a simple volume calculation suggests. A 10–15% allowance is standard for most surface cracks. Increase it to 20–25% for rough, porous, or branching cracks.

Can I use this for control joints?

Yes. Enter the joint length, width, and depth exactly as you would a crack. For control joints, product selection matters more than quantity — use a semi-rigid epoxy or polyurea joint filler rather than a rigid crack filler, so the joint edges are supported. It will not move with the joint: as the slab keeps shrinking it separates slightly from the joint edge, which is expected and not a failure.

Should I add primer before injecting crack filler?

Most epoxy injection systems are self-priming and do not require a separate primer step. However, if the crack has been contaminated with oil, release agents, or moisture, clean and dry it thoroughly before injection. Some polyurethane foams actually react with moisture to expand and fill — check your product data sheet.

Important Notes

  • Volume is calculated as length × width × depth — actual usage increases with crack taper, branching, and surface absorption
  • Always order at least one extra cartridge as a buffer — running short mid-crack risks leaving voids
  • Clean cracks of dust, debris, and contamination before injecting — adhesion failures are almost always a prep issue
  • An active (moving) crack cannot be held shut by any filler: honor it as a joint with a flexible sealant, or saw cut it back through the coating. Rigid and semi-rigid fillers will crack or separate
  • Measure the full floor area with the Square Meter & Square Foot Calculator to size base coat quantities once prep and crack repair are complete
Resin Mixing Ratio CalculatorGet exact Part A and Part B quantities when mixing bulk crack repair resin.Grinding Time CalculatorEstimate the grind and prep time before filling cracks.Square Meter & Square Foot CalculatorMeasure the floor area for the full coating job after repairs.
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