Self-Leveling Concrete Calculator

How do you calculate how much self-leveling concrete you need?

Self-leveling concrete, sold as self-leveling underlayment or compound, is bought by the bag, and every bag fills a fixed volume. Find the volume of the layer you are pouring, then divide by what one bag fills:

Volume (ft³) = floor area (ft²) × average thickness (in) ÷ 12
Bags = volume ÷ yield per bag (ft³), rounded up

The calculator above starts with a yield of 0.4375 ft³ per 50 lb bag. That figure comes from the SikaLevel data sheet, which lists 21 ft² of coverage per bag at 1/4 in and 42 ft² at 1/8 in; both work out to 0.4375 ft³. Products differ, so replace it with the yield or coverage on your own bag. If a bag lists only coverage at a depth, convert it: yield = coverage (ft²) × depth (in) ÷ 12. CustomTech TechLevel 100, for example, lists 22.99–24.10 ft² at 1/4 in, which is about 0.48–0.50 ft³.

1. Measure the floor. Length × width in feet for each room or rectangle, then add them.
2. Find the average depth. Self-leveler fills low spots, so the depth changes across the floor. Use the average, not the deepest point (see the sloped-floor section below).
3. Enter the bag yield from your product’s bag or data sheet.
4. Keep the 10% extra for surface texture, porosity and what stays in the bucket.

How many bags of self-leveler do I need? Coverage table

The table below answers the common floor sizes at four depths. Each cell shows the volume with 10% extra and the number of 50 lb bags at 0.4375 ft³ per bag, the SikaLevel figure. If your product yields more per bag, you will need slightly fewer.

Depth drives the order more than area. Going from 1/8 in to 1/4 in doubles the bags, and a single inch over a 200 ft² room takes 42 bags. Check that your product is rated for the depth you plan; not every underlayment can go to 1 in in one lift.

How much does a bag of self-leveler cover at each thickness?

Coverage per bag is the yield divided by the depth in feet. At 0.4375 ft³ per bag, a 50 lb bag covers:

SikaLevel’s own table lists 42 ft² at 1/8 in, 21 ft² at 1/4 in, 11 ft² at 1/2 in and 5.3 ft² at 1 in, which matches these figures to within half a square foot. The 1/2 in figure on the data sheet is slightly more generous than the straight calculation. CustomTech lists 22.99–24.10 ft² at 1/4 in for TechLevel 100 and 150, 21.58–22.74 ft² for TechLevel 125, and 22.75–23.66 ft² for TechLevel XP-1, all for 50 lb bags. The spread between brands at 1/4 in is about 21 to 24 ft² per bag, so on a large floor it pays to enter your product’s exact number.

How do I estimate self-leveler for an uneven or sloped floor?

Use the average depth, not the maximum. Self-leveler finds its own level, so on a floor that dips or slopes the layer is deep in some places and thin in others. The volume you need is the floor area times the average depth.

The simplest way to find it: snap a level line or use a long straightedge and a laser, then measure the gap to the finished height at a grid of points, about every 2 to 3 ft. Add the readings and divide by the number of readings. For a floor that slopes evenly from one side to the other, the average is half the deepest point.

If the deepest spot is deeper than your product’s maximum, fill it first with a patching product or a separate lift, as the manufacturer directs, and then pour the self-leveler over the whole floor. SikaLevel, for example, can be extended with sand or pea gravel for deeper areas, and its data sheet says to expect coverage to rise by about 0.16 ft³ per 25 lb of aggregate.

How thick can self-leveling concrete be?

Each product has its own minimum and maximum, printed on the data sheet. From the two sheets we checked:

• SikaLevel: typical application 1/8 to 2 in (3 to 50 mm), with 2 in in localized areas, and up to 2.5 in when extended with pre-washed 3/8 in pea gravel.
• CustomTech TechLevel 100: levels floors from 3/16 to 1.5 in (4.8 mm to 3.8 cm).
• CustomTech TechLevel 125: a deep-pour product rated up to 3 in in one pour.
• CustomTech TechLevel LITE: from feather edge up to 2 in in one pour, per the sell sheet (which also prints 2.5 cm; confirm on the product data sheet).

Stay within the thickness range on your product’s data sheet. If your average depth falls outside the range on your bag, pick a different product or split the work into lifts, priming between them as the manufacturer directs.

Self-leveling concrete in metric

In metric the calculation is simpler: one square metre at one millimetre deep is exactly one litre. So the litres you need equal the area in m² times the depth in mm.

A 50 lb bag with a yield of 0.4375 ft³ fills about 12.39 L. That covers about 4.13 m² at 3 mm, 2.48 m² at 5 mm and 1.24 m² at 10 mm. A 10 m² floor at 5 mm needs 50 L, or 55 L with 10% extra, which is 5 bags. Products sold in metric countries may come in different bag sizes with a different yield, so read the litres or m² per bag from your packaging.

Common mistakes when calculating self-leveler

Most self-leveler shortfalls come from depth, not area. These are the mistakes that cost the most:

• Entering the depth in feet instead of inches. On 200 ft² at 1/4 in you need 10 bags before the 10% extra. Treat 0.25 as feet and the math says 115 bags.
• Using the deepest point as the depth. On a 10 × 12 ft room sloping from 0 to 1/2 in, the deepest point gives 13 bags; the average depth gives 7.
• Rounding 3/16 in down to 1/8 in. On 200 ft² that is the difference between 8 bags and 6, enough to run out mid-pour.
• Using a concrete-mix yield. An 80 lb bag of concrete mix yields about 0.60 ft³, so 200 ft² at 1/4 in would look like 8 bags. At 0.4375 ft³ per 50 lb bag of self-leveler it is 11.
• Skipping the extra. SikaLevel’s coverage figures exclude surface profile, porosity and waste. A shot-blasted or porous floor absorbs more than a smooth one.
• Adding water to stretch the bags. Use the exact water on the bag; SikaLevel calls for 1 gallon per 50 lb bag and warns against over-watering. Extra water does not add usable coverage.

Self-leveling concrete vs concrete mix and slab calculators: which one to use

This page is for thin layers, from about 1/8 in to the maximum on your product’s data sheet. Switch tools when the job is thicker or structural:

• Concrete slab calculator: new slabs, pads and floors 2 in thick or more, in cubic yards and bags.
• Concrete bag calculator: how many 40, 50, 60, 80 or 90 lb bags of concrete mix fill a volume. QUIKRETE rates its Concrete Mix for pours 2 in or more.
• QUIKRETE calculator and Sakrete calculator: bag counts for those brands’ concrete mixes.
• Square feet to cubic yards: converting an area and depth to cubic yards for a ready-mix order.

For a deep fill, the numbers favor concrete. At 2 in over 200 ft², the volume with 10% extra is 36.67 ft³: about 84 bags of self-leveler at 0.4375 ft³ each, or 62 bags of 80 lb concrete mix. A common approach is to bring the floor close to level with concrete and finish with a thin self-leveling layer, but follow the flooring manufacturer’s requirements for what goes under their product.

Where the coverage figures come from

The default yield of 0.4375 ft³ per 50 lb bag comes from the SikaLevel product data sheet (Sika USA, May 2026, version 01.06), which lists 42 ft² at 1/8 in, 21 ft² at 1/4 in, 11 ft² at 1/2 in and 5.3 ft² at 1 in, along with a density of 133 lb/ft³, 1 gallon of water per 50 lb bag and an application range of 1/8 to 2 in. The CustomTech coverage and thickness figures come from Custom Building Products’ self-leveling underlayment sell sheet, which describes its chart as for estimating purposes and notes that coverage varies with installation practices and jobsite conditions. The 2 in minimum for concrete mix comes from the QUIKRETE Concrete Mix (No. 1101) data sheet. Brand names identify the data sheets only; this site is independent and not affiliated with any manufacturer.