Cold Patch Calculator

How many bags of cold patch do I need?

A cold patch calculator turns the size of a pothole into a bag count. Multiply the repair length by its width in feet, multiply by the depth in inches ÷ 12 to get cubic feet, then divide by 0.45, the cubic feet a 50-lb bag of cold-mix asphalt fills. The answer is rounded up to whole bags. A 4 × 3 ft patch 2 inches deep is 2 cubic feet, which is 4.44 bags, so you buy 5.

Enter the repair area and depth, then your price per bag. The total shows what the bags will cost at the store.

The formula in plain words

• Cubic feet = length × width × (depth in inches ÷ 12)
• Bags = cubic feet ÷ 0.45, rounded up
• Cost = bags × price per bag

Depth is the real depth of the damage, down to firm base. A hole that looks 1 inch deep at the edge is often 3 inches deep in the middle once the loose chunks come out.

Worked examples

Both use $20 per bag.

1. Driveway pothole with broken edges, framed at 4 × 3 ft, 2 in deep**

• Volume: 4 × 3 × (2 ÷ 12) = 2.00 cu ft
• Bags: 2.00 ÷ 0.45 = 4.44, rounded up to 5 bags
• Cost: 5 × $20 = $100

2. Single deep pothole, 2 × 2 ft, 3 in deep**

• Volume: 2 × 2 × (3 ÷ 12) = 1.00 cu ft
• Bags: 1.00 ÷ 0.45 = 2.22, rounded up to 3 bags
• Cost: 3 × $20 = $60

The second hole has half the area of the first but is 50% deeper, so depth moves the bag count as much as width does.

Cold patch bags by repair size

At 0.45 cu ft per 50-lb bag, rounded up.

Repair size	Depth	Cubic feet	Bags
1 × 1 ft	2 in	0.17	1
2 × 2 ft	2 in	0.67	2
3 × 3 ft	2 in	1.50	4
2 × 2 ft	4 in	1.33	3
4 × 4 ft	2 in	2.67	6
6 × 4 ft	3 in	6.00	14
8 × 6 ft	2 in	8.00	18

Once a repair needs more than about 15 to 20 bags, get a price on hot-mix asphalt from a local paving crew. Bulk asphalt is sold by the ton and a large patch often costs less that way.

How to prepare and measure the hole

1. Clean it out. Remove loose asphalt, dirt, and standing water. Cold patch will not grip a wet, crumbly hole.
2. Square it up. Trim the edges back to solid pavement with a chisel or saw. Frame the measurement around that square, not the ragged hole.
3. Measure depth at the center with a ruler or a straightedge laid across the hole.
4. Add base if it is deep. If the hole goes through to soil, put compacted gravel in the bottom so the patch sits no more than about 3 to 4 inches thick.

Cold patch weight

Each bag holds 50 lb in 0.45 cubic feet, so the material weighs about 111 lb per cubic foot before compaction. The 5 bags in the first example are 250 lb, which fits in a car trunk but is a lot to carry in one trip. Larger repairs over 10 bags are easier with a truck or a delivery.

Common mistakes

• Patching over water. Water under the patch freezes and pushes it out. Sweep or blow the hole dry first.
• Filling flush with the pavement. Cold patch compacts down. Leave it slightly mounded before you tamp, or it ends up as a dip.
• Tamping only once. A single pass leaves the bottom loose. Tamp each lift hard with a hand tamper.
• Using cold patch for large areas. It works best for spot repairs. Wide areas tend to rut under traffic.
• Measuring only the visible hole. The cracked ring around a pothole usually needs to come out too.

Related calculators

If the whole surface is tired, the asphalt calculator sizes a full repave in tons. Once patches cure, protect the driveway with the sealcoat calculator. For gravel driveways, recycled asphalt millings are a cheaper way to fill ruts.