Self Leveling Compound Calculator
Self leveling compound calculator for a floor. Enter the room size and how far it dips to get bags of floor leveler, primer, cost and the flatness you need to hit.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Bags to buy
- 14 bags of 50 lb
- 144 sq ft at an average 0.5 in, plus 5% waste. About 11 sq ft per bag at this depth
- Compound volume
- 6 cu ft
- Average depth 0.5 in, deepest point 0.75 in, thinnest 0.25 in
- Primer
- 1 gallon
- 1 coat at 250 sq ft per gallon. Prime once, twice if the slab is porous enough to drink the first coat
- Material cost
- $633
- $588 of compound plus $45 of primer, or $4 per sq ft of floor
- Deepest pour
- 0.75 in
- Within the range a straight mix handles. No aggregate extension needed
- Flatness to hit
- 1/4 in in 10 ft
- ANSI A108.02 for tile under 15 in. Tile 15 in or larger wants 1/8 in in 10 ft, and a large format tile on a wavy floor is what causes lippage
- Mixing water
- 8.4 gal total
- About 5 quarts a bag, and the amount is not a suggestion. Extra water makes it flow better and cures weak, dusty and cracked
- Working time
- 10 to 20 minutes
- Mix, pour and spread one batch before starting the next, and pour wet into wet. A batch that sets before the next one joins it leaves a visible cold seam
- Planning estimate only
- Read the bag yield
- Yield per bag, minimum and maximum thickness and primer type all vary by product, and the bag overrides anything here
Self Leveling Compound formula
Average depth = Minimum thickness at the high spot + Dip / 2
Volume = Area x Average depth / 12
Bags = Volume / Bag yield, plus 5% waste. A 50 lb bag yields about 0.45 cu ft
Square feet per bag = Bag yield x 12 / Average depth, so 43 sq ft at 1/8 in and 11 at 1/2 in
Primer = Area x Coats / 250 sq ft per gallonWorked example
A 20 x 14 ft kitchen over a plywood subfloor, 1 in out of level across the room, going under large format tile.
Plywood forces the minimum up to 1/2 in over lath, so the average depth is 1 in and the deepest point is 1.5 in. The 280 sq ft floor takes 23.3 cubic feet, which is 55 bags of 50 lb, plus 3 gallons of primer for two coats. That is about $2,445 of material, or $8.73 a square foot, which is more than the tile going over it. Past 1 in most products allow pea gravel added to the mix, and using it here would cut the bag count by roughly a third. This is also the case where a sleeper or a plywood shim layer is worth pricing against the leveler.
Quick reference
| Average depth | Sq ft per bag | Bags per 100 sq ft |
|---|---|---|
| 1/8 in | 43 | 2.4 |
| 1/4 in | 22 | 4.7 |
| 3/8 in | 14 | 7.0 |
| 1/2 in | 11 | 9.3 |
| 3/4 in | 7 | 14.0 |
| 1 in | 5 | 18.6 |
Average depth, not the deepest point
The most common mistake is buying for the worst spot. A floor that dips half an inch is only half an inch low in one place; across the room the fill tapers to nothing. The usable rule is average depth equals the minimum thickness you need at the high point plus half the measured dip. Multiply that by the area and divide by the bag yield.
Depth punishes you fast because coverage is inversely proportional to it. A 50 pound bag covers about 43 square feet at an eighth of an inch, 22 at a quarter, and 11 at a half. That is why the substrate matters so much: concrete lets you feather down to an eighth of an inch, while plywood usually needs lath and a half inch minimum, which is four times the material for the same room.
Primer, water and working time decide whether it works
Three things cause almost every failure. The first is skipping primer. A bare substrate pulls water out of the mix as it sits, and what cures is pinholed, chalky and not bonded. Primer is cheap, takes an hour, and is not optional on any substrate. The second is adding water. The mix flows because it is formulated to, and extra water buys a moment of easier spreading in exchange for a weak, dusty surface that cracks.
The third is time. Working time is 10 to 20 minutes, and batches have to go in wet into wet or the seam between them stays visible and can telegraph through the finished floor. On anything past a couple of hundred square feet that means one person mixing continuously while another pours and spreads. Dam the doorways and any floor penetration first, because the material is genuinely liquid and it will find the stairwell.
What this calculator leaves out
Anything structural. Self leveling compound adds no stiffness, so a bouncy floor has to be sistered or blocked first, and TCNA puts the limit at L/360 deflection for ceramic and L/720 for stone. It does not price metal lath and fasteners over a wood subfloor, crack isolation or uncoupling membrane, a moisture mitigation coating over a slab that failed a test, or the grinding and shot blasting a contaminated slab needs. Nor does it cover deck mud or a dry pack mortar bed, which is a different product for shower pans and sloped floors, or a true slope where the answer is a mortar bed or a sleeper system rather than bag after bag of leveler. Yields, minimum and maximum thicknesses and primer type vary by product, and the bag overrides this page.
Code limits that apply
- ANSI A108.02
Substrate flat to 1/4 in in 10 ft for tile with any edge under 15 in
If you miss it: Tile set on a wavy floor lippages at the edges, and no amount of thinset hides it
- ANSI A108.02
Substrate flat to 1/8 in in 10 ft for tile 15 in or larger on any edge
If you miss it: Large format tile on a floor flat only to the smaller tolerance shows every high spot as a raised edge
- TCNA Handbook
Wood framing deflection under L/360 for ceramic tile and L/720 for natural stone
If you miss it: A springy floor cracks the tile and the grout no matter how flat the leveler made it
- ASTM F710
Concrete tested for moisture and cleaned to bare before resilient flooring goes down
If you miss it: Moisture under a vapor tight floor covering debonds the adhesive and the leveler with it
- ASTM F2170
In situ relative humidity in the slab at or under the flooring manufacturer limit, commonly 75 to 80%
If you miss it: A slab over the limit fails the flooring warranty even when the surface feels dry
Rows marked checked produce a warning in the results when an entry crosses the limit. The others are on the plans or on site and this calculator does not test them. Local amendments can be stricter; the adopted edition and the inspector govern.
Mistakes that cost money
- Skipping primer. The substrate pulls water out of the mix, and the result is pinholes, a chalky surface and no bond at all.
- Adding extra water to make it flow. It flows because it is designed to, and the extra water cures weak, dusty and cracked.
- Pouring over a floor that moves. Leveler is not structural, so a bouncy joist bay has to be stiffened first or the new surface cracks.
- Mixing one batch at a time on a big floor. Working time is 10 to 20 minutes and a seam between a set batch and a fresh one shows.
- Forgetting to dam the doorways and any penetration. It is liquid, and it will find the stairwell, the floor register and the room next door.
- Using it to fix a slope rather than a dip. Leveling a 2 in fall across a room takes a mortar bed or a sleeper system, not bag after bag of leveler.
Key facts
- A 50 lb bag of self leveling compound yields about 0.45 cubic feet, which covers roughly 43 square feet at 1/8 in and only 11 square feet at 1/2 in.
- Average fill depth is the minimum thickness plus half the measured dip, because a sloping floor is only at its deepest in one place.
- ANSI A108.02 asks for a substrate flat to 1/4 in in 10 ft for tile under 15 in, and 1/8 in in 10 ft for tile 15 in and larger.
- Self leveling compound over a plywood subfloor usually needs metal lath and a 1/2 in minimum thickness, which quadruples the material over the same job on concrete.
- Most products allow pea gravel to extend the mix above about 1 in of depth, which cuts the cost of a deep pour by roughly a third.
- Working time is 10 to 20 minutes, so a floor larger than a few hundred square feet needs more than one person mixing.
Frequently asked questions
How much self leveling compound do I need?
Take the minimum thickness you need at the high spot, add half the measured dip, and multiply by the floor area. A 12 x 12 ft room half an inch out of level over concrete takes about 14 bags of 50 lb plus a gallon of primer.
How many square feet does a bag of floor leveler cover?
A 50 lb bag yields about 0.45 cubic feet, so roughly 43 sq ft at 1/8 in, 22 at 1/4 in and 11 at 1/2 in. Coverage falls in direct proportion to depth, so check the average depth before the bag count.
Do I have to prime before self leveling compound?
Yes, on every substrate. Without primer the floor pulls water out of the mix as it cures, leaving pinholes, a chalky surface and a bond that fails. Porous concrete and wood usually want two coats.
Can you use self leveling compound over plywood?
Yes with the right product, but most require metal lath fastened to the subfloor and a 1/2 in minimum thickness over it, which is four times the material of the same room on concrete. The floor also has to be stiff enough first.
Sources and references
- Tile installation standards and substrate requirements (Tile Council of North America)
- Surface preparation and underlayment products (Custom Building Products)
- Slabs on ground, flatness and surface preparation (American Concrete Institute)
Next steps for this project
The usual order for a flooring & tile project. See all flooring & tile calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.