How it works
The formula
bags = floor area ÷ coverage per bag, rounded up
Assumptions
- Coverage at 1/8 in: 43 sq ft for a 40 lb bag of Henry 555 LevelPro, and 46 sq ft for a 50 lb bag of Custom LevelQuik RS (its data sheet says 46 to 48 sq ft, and 23 to 24 at 1/4 in). Other brands differ, so check the bag.
- The depth is an average over the whole floor. If you're only filling low spots, measure their area and depth separately; feathering out to zero takes less.
- Typical price about $35–$65 a bag (checked Oct 2026). Primer is extra: most brands require their own primer on the subfloor first.
Worked example
A 10 × 12 ft room, 1/4 in deep, 50 lb bags
- Floor: 10 × 12 = 120 sq ft
- Each bag at 1/4 in: 46 × (1/8 ÷ 1/4) = 23 sq ft
- 120 ÷ 23 = 5.2 → 6 bags
50 lb bags by room and depth
| Room | 1/8 in | 1/4 in | 3/8 in | 1/2 in |
|---|---|---|---|---|
| 10 × 10 ft | 3 | 5 | 7 | 9 |
| 10 × 12 ft | 3 | 6 | 8 | 11 |
| 12 × 14 ft | 4 | 8 | 11 | 15 |
| 15 × 20 ft | 7 | 14 | 20 | 27 |
One 50 lb bag covers about 46 sq ft at 1/8 in and 23 at 1/4 in.
Questions people ask
How much does a bag of self-leveler cover?
About 43 to 48 sq ft at 1/8 in for a 40 to 50 lb bag, and half that at 1/4 in. Henry 555 lists 43 sq ft at 1/8 in for its 40 lb bag; Custom LevelQuik RS lists 46 to 48 sq ft at 1/8 in and 23 to 24 at 1/4 in for its 50 lb bag.
How thick can self-leveler be poured?
It depends on the product: many go from a feather edge up to about 1 in or more in one pour, some deeper with added aggregate. Check the bag, and pour in one go so it doesn't set in layers.
Do I need primer?
Almost always. Most makers require their own primer on the subfloor so the underlayment bonds and doesn't lose water into the subfloor too fast. Wood subfloors may also need metal lath.
How long before I can walk on it or lay flooring?
Many products take light foot traffic in a few hours, and tile can often go on the same day, but wood, vinyl and other moisture-sensitive floors usually need a day or more. The bag's cure times rule.