Estimate the self-leveling underlayment for a floor. Enter the area and the average depth, or the thinnest and deepest points of an uneven floor, and get the number of bags, the mixing water and the primer to buy.
Last updated:
Units
sq ft
m²
Depth
in
1/8 in = 0.125, 1/4 in = 0.25, 1/2 in = 0.5
mm
in
in
mm
mm
Product
ft³
A 50 lb (22.7 kg) bag typically yields 0.4–0.5 ft³ (11–14 L); see the bag
lb
qt
Typically 4.5–5.5 qt (≈ 4.3–5.2 L) per 50 lb bag
sq ft
As diluted for your substrate; check the primer label
%
Low spots, leaks at edges, mix left in the bucket
Enter your values to see the result.
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How to use the Self-Leveling Concrete Calculator
Enter the floor area in square feet or square meters.
Enter the depth: an average, or the thinnest and deepest points if the floor slopes.
Check the product values: yield per bag, bag weight and water per bag from your bag.
Set the primer coverage and number of coats.
Read the bags, water and primer, and compare other depths in the table.
Self-leveler formulas
Average depth = (thinnest + deepest) ÷ 2 for an evenly sloping floor
Volume (ft³) = area (sq ft) × average depth (in) ÷ 12
Bags = volume × (1 + waste) ÷ yield per bag (ft³), rounded up
Water = bags × water per bag; primer = area × coats ÷ coverage per gallon
Metric: volume (L) = area (m²) × depth (mm). 20 m² at 5 mm is 100 L; a 22.7 kg (50 lb) bag yielding about 12.7 L makes that 8 bags before waste.
Coverage of one 50 lb bag (0.45 ft³ yield)
Depth
Metric
Coverage per bag
Bags per 100 sq ft
1/8 in
3 mm
43 sq ft
2.3
3/16 in
5 mm
29 sq ft
3.5
1/4 in
6 mm
22 sq ft
4.6
3/8 in
10 mm
14 sq ft
6.9
1/2 in
13 mm
11 sq ft
9.3
1 in
25 mm
5.4 sq ft
18.5
Pouring tips
Clean the floor of dust, paint, adhesive and grease, and fill cracks and gaps so the liquid cannot leak away.
Install foam edge strip or dams at walls and doorways and plug floor drains.
Mix with a paddle on a drill for the time on the bag, pour in ribbons and use a gauge rake or smoother to guide the flow; spiked shoes let you walk in it.
Keep the room free of drafts and direct sun while it cures, and wait the stated time before installing flooring.
Frequently asked questions
How much does a 50 lb bag of self-leveler cover?
A typical 50 lb bag yields about 0.45 cubic feet, which covers roughly 43 sq ft at 1/8 in, 22 sq ft at 1/4 in and 11 sq ft at 1/2 in. Yields vary by brand from about 0.4 to 0.5 ft³, so enter the figure on your bag.
How do I estimate self-leveler for an uneven floor?
Find the thinnest point you need to cover (usually at least 1/8 in) and the deepest low spot, then use their average if the floor slopes fairly evenly. For floors with a few isolated dips, measure each area and depth separately and add them up, or use a long straightedge and a grid of measurements.
How much water do I mix with self-leveling underlayment?
Most 50 lb bags take about 4.5 to 5.5 quarts of clean, cool water. Measure it exactly every time; extra water makes the pour weak, dusty and prone to cracking.
Do I need primer before self-leveling concrete?
Almost always. Primer seals porous concrete so it does not pull water out of the leveler, prevents pinholes and improves the bond. Very porous concrete often needs two coats, and wood subfloors need primer plus metal lath per the product's instructions.
What is the minimum and maximum thickness for self-leveler?
Many products need at least 1/8 in (3 mm) over the whole area and can be poured neat up to about 1 in (25 mm); some go deeper or allow aggregate extension. Feathering to zero needs a separate patching compound.
How is the number of bags calculated?
Volume (ft³) = area (sq ft) × average depth (in) ÷ 12. Add a waste allowance, then divide by the yield per bag and round up. For 200 sq ft at 1/4 in: 200 × 0.25 ÷ 12 = 4.17 ft³, × 1.10 = 4.58 ft³, ÷ 0.45 = 10.2, so 11 bags.
How fast do I have to work?
Self-levelers typically have a flow time of about 10–20 minutes, so mix bag after bag continuously and keep a wet edge. Plan the pour, block doorways and drains, and have a helper mixing while you spread.
Are all the tools on FreeToolCabin tested for quality and accuracy?
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