Bags needed at a 1/4 in average pour depth
Straight data-sheet coverage with no waste allowance, so add about 10 percent for spillage and barrel residue. Bag counts round up per product. Bag sizes differ (Henry 40 lb, CUSTOM and Mapei 50 lb, Ardex 55 lb).
| Room size | Area | Henry 555 (40 lb) | LevelQuik RS (50 lb) | Novoplan 2 Plus (50 lb) | Ardex K 15 (55 lb) |
|---|---|---|---|---|---|
| 5 x 8 ft | 40 sq ft | 2 | 2 | 2 | 2 |
| 8 x 10 ft | 80 sq ft | 4 | 4 | 4 | 3 |
| 10 x 12 ft | 120 sq ft | 6 | 6 | 5 | 4 |
| 12 x 12 ft | 144 sq ft | 7 | 7 | 6 | 5 |
| 12 x 15 ft | 180 sq ft | 9 | 8 | 8 | 6 |
| 15 x 20 ft | 300 sq ft | 14 | 14 | 13 | 10 |
Coverage per bag by pour depth (sq ft)
Published TDS figures where the manufacturer states them. Intermediate depths are derived pro rata and rounded to the nearest tenth. LevelQuik RS figures use the conservative end of the published 46–48 sq ft range. The K 15 figure at 1/8 in derives from its published 30 sq ft at 1/4 in. Novoplan 2 Plus publishes 9 sq ft at 3/4 in (the linear figure is 8, and the calculator uses the linear yield).
| Depth | Henry 555 (40 lb) | LevelQuik RS (50 lb) | Novoplan 2 Plus (50 lb) | Ardex K 15 (55 lb) |
|---|---|---|---|---|
| 1/8 in | 43 | 46 | 48 | 60 |
| 1/4 in | 21.5 | 23 | 24 | 30 |
| 3/8 in | 14.3 | 15.3 | 16 | 20 |
| 1/2 in | 10.8 | 11.5 | 12 | 15 |
| 3/4 in | 7.2 | 7.7 | 9 | 10 |
| 1 in | 5.4 | 5.8 | 6 | 7.5 |
Depth limits and timing by product
All times at 70 F per the manufacturer TDS. Moisture-sensitive coverings are vinyl, LVP, wood, rubber and similar. Novoplan 2 Plus flooring time is stated at a full 1 in thickness and shortens at thinner pours.
| Product | Bag | At 1/8 in | Max single pour neat | Max with aggregate | Walk on | Tile | Other coverings | Where sold |
|---|---|---|---|---|---|---|---|---|
| Henry 555 LevelPro | 40 lb | 43 sq ft | 1.5 in | 5 in with pea gravel | 2–3 h | 6 h | 16 h | home centers |
| CUSTOM LevelQuik RS | 50 lb | 46–48 sq ft | 1.5 in | not listed on TDS | 2–4 h | over 4 h | 16 h | home centers |
| Mapei Novoplan 2 Plus | 50 lb | 48 sq ft | 1 in | not listed on TDS | 2–3 h | 24 h | 2–3 days at 1 in | home centers, tile suppliers |
| Ardex K 15 | 55 lb | 60 sq ft (derived) | 1.5 in | 5 in with pea gravel | 2–3 h | 6 h | 16 h | flooring distributors only |
Required primer by product
Coverage per coat on porous concrete at the stated dilution, from each primer TDS. Very absorbent slabs take a first coat at 3 parts water to 1 part primer, then a second at 1:1 (the double-prime method Henry and Ardex describe). CUSTOM instead calls for a second coat of its diluted primer. Wood subfloors take undiluted primer and, for Henry 555 and LevelQuik RS, metal lath.
| Underlayment | Primer | Dilution on porous concrete | Coverage | Dry time |
|---|---|---|---|---|
| Henry 555 | Henry 554 | 1:1 with water | 100–150 sq ft per qt | 3–24 h |
| LevelQuik RS | LevelQuik Primer | up to 1:3 primer to water | 150–300 sq ft per qt | 1–3 h, re-prime after 12 h |
| Novoplan 2 Plus | Mapei Primer T | 1:1 to 2:1 water to primer | 50–100 sq ft per qt | 2–3 h before pour, 24 h max |
| Ardex K 15 | Ardex P 51 | 1:1 with water | 400–600 sq ft per gal | 30 min–24 h |
How many bags of self leveler you need
One 50 lb bag of self leveling underlayment covers 46–48 sq ft at 1/8 in. That figure comes straight from the CUSTOM LevelQuik RS data sheet, and Mapei Novoplan 2 Plus publishes 48 sq ft for the same bag and depth.
Henry 555 LevelPro comes in a smaller 40 lb bag, and Ardex K 15 in a 55 lb one. Their yields differ again. Henry publishes 43 sq ft at 1/8 in, and K 15 publishes 30 sq ft at 1/4 in, which is 60 sq ft at 1/8 in pro rata. The coverage table above carries the rest. Bag sizes differ, so a bag count for one product doesn’t carry over to another.
The calculator multiplies room area by average pour depth to get a demand in sq-ft-inches, adds your waste allowance, and divides by the published per-bag yield for the product you picked. Bags round up. Primer is a separate product and rounds up separately. The same bags sell in Canada under the same names with metric labels (22.68 kg for a 50 lb bag).
Self leveling concrete, self leveling compound, self leveling cement and self leveling underlayment all name the same bagged product family. The data sheets say underlayment because none of these products is a wear surface. Every one of them has to be covered with tile, vinyl, wood or carpet.
Average depth, not low-spot depth
Real floors are low in spots, not uniformly. Henry 555, Novoplan 2 Plus and Ardex K 15 each set the same rule. Pour at least 1/8 in over the highest point in the floor.
The low spots then take whatever extra material they need, which is why the number that sizes your order is the average depth across the room. Ardex is explicit about where that usually lands. Its K 15 data sheet says a 1/8 in minimum over the high point typically results in an average thickness of 1/4 in or more over the entire floor.
To find your numbers, lay a straightedge or a long level across the floor in several directions and measure the deepest gap under it. That reading is the low spot depth. If the dips are broad (the floor sags toward the middle, or falls toward one wall) the average is roughly 1/8 in plus half the deepest dip. So a floor with a 1/2 in dip averages about 3/8 in. A mostly flat floor with a couple of local dips sits closer to 3/16 in.
Why ask for the average directly instead of working it out from the low spot? Because a 1/2 in dip that spans the room and a 1/2 in dip in one corner read the same under a straightedge, and they need very different amounts of material. You can see the shape of your floor. A formula can’t. The deepest low spot field does one job only, which is checking your floor against the single-pour depth limit of the product. Running out of material mid-pour is the failure you really want to avoid, so when in doubt, round the average up.
Primer is part of the order
Every product in this calculator requires its own primer. Pouring on bare concrete risks pinholes, bubbles and bond failure, and skipping the primer voids the warranty.
Each system names its own. Henry 555 takes Henry 554, LevelQuik RS takes LevelQuik Primer, Novoplan 2 Plus takes Mapei Primer T, and Ardex K 15 takes P 51. Coverage on porous concrete varies a lot, from 50–100 sq ft per quart for Primer T to 150–300 sq ft per quart for LevelQuik Primer, and each one has its own dilution (the primer table above has all of it). The calculator sizes primer from your floor area at the conservative end of each published range.
Very absorbent concrete usually takes a double prime. Henry and Ardex both specify a first coat diluted 3:1 with water, then a second at 1:1. CUSTOM calls for a second coat of its diluted primer instead. Henry names the tell (the primer disappearing into the slab in under 10 minutes), so if you see that, plan on the second coat.
Wood subfloors are a different system. Henry 555 and LevelQuik RS both require undiluted primer on wood plus galvanized metal lath stapled about every 6 to 8 in before the pour. The current Ardex K 15 data sheet doesn’t list wood as a suitable substrate at all, and coverage drops on wood too (LevelQuik Primer publishes 75–150 sq ft per quart there). Non-porous surfaces such as porcelain or epoxy need a different primer entirely. CUSTOM uses MBP, Ardex uses P 82, and Mapei uses undiluted Primer T. Henry 554 isn’t rated for them.
Mix every bag, then pour once
The clock is short on all of these. Henry 555 and Ardex K 15 give you a 10 minute flow time at 70 F. Novoplan 2 Plus allows up to 15 minutes, and LevelQuik RS lists a pot life over 15 minutes with a healing time over 18 minutes. None of that is really enough to mix bags one at a time against a pour that’s already on the floor. The earlier material skins over and you get a cold joint (a visible ridge that has to be ground flat).
So self leveling gets batch mixed. Mix in a barrel or several 5 gallon buckets with a 1/2 in drill and paddle at 650 rpm minimum, 2 to 3 minutes per batch, with one person mixing while another pours and spreads. Ardex directs mixing two bags at a time. Mapei says to work as a team to keep a continuous flow of wet material, and CUSTOM says to keep a wet edge when pouring multiple mixes.
Measure the water for every bag before you start.
Overwatering is the classic failure, and a yellowish foam on the mix means you’ve already done it. Anything above about 4 bags is realistically a two-person job. For large floors, LevelQuik RS, Novoplan 2 Plus and K 15 can all be pumped with a mixing pump instead.
Depth limits, thick fills and feather edges
Henry 555, LevelQuik RS and Ardex K 15 each pour up to 1.5 in neat in a single lift. Novoplan 2 Plus caps a single lift at 1 in, with a second lift allowed after 1 day. One extra Ardex rule applies over non-porous substrates primed with VB 100, P 82 or P 4, where K 15 is limited to 1/4 in.
For deeper fills, Henry 555 and K 15 extend with washed 1/8–3/8 in pea gravel up to 5 in total. Both data sheets carry the same rules. Aggregate no larger than 1/3 the depth of the pour, mixed 1 part gravel to 1 part mixed material by volume, and never sand. The aggregate lift then needs a neat finish coat over it, primed first (Henry 564 at 1:1 after 12 to 16 hours on Henry 555, P 51 at 1:1 after 16 hours on K 15).
At the thin end, Henry 555 and LevelQuik RS both feather to match existing elevations. K 15 tapers only as thin as the sand in the mix allows, so for a true featheredge Ardex points you to Feather Finish or another unsanded patch.
Those patch products are a different class. Don’t estimate them with this calculator.
Walk-on times and flooring times
You can walk on most of these in 2–3 hours at 70 F. That covers Henry 555, Novoplan 2 Plus and Ardex K 15, while LevelQuik RS lists 2–4 hours. Cold slabs and high humidity stretch every one of those numbers, sometimes by a lot.
Tile goes down fastest. Figure 6 hours for Henry 555 and K 15, just over 4 hours for LevelQuik RS, and 24 hours for Novoplan 2 Plus.
Moisture-sensitive coverings (vinyl, LVP, wood, rubber) wait 16 hours on Henry 555, LevelQuik RS and K 15. Novoplan 2 Plus lists 2–3 days at a full 1 in thickness for those floors, with shorter times at thinner depths. Check the moisture limits of your flooring adhesive before going over any of them.
Availability differs by brand. Henry 555, LevelQuik RS and Novoplan 2 Plus sell through home centers. The Ardex K 15 data sheet marks it for professional use and states it isn’t sold through home improvement centers, so you’ll be buying it at a flooring distributor. Check with your local supplier on stock before you plan the pour around it.
Common questions
How much self leveler do I need?
Once real depth is counted, most rooms need more bags than people expect. Multiply floor area in sq ft by average pour depth in inches, then divide by the per-bag yield and round up. The yields are 5.375 sq-ft-in for Henry 555 (40 lb bag), 5.75 for LevelQuik RS, 6 for Novoplan 2 Plus and 7.5 for Ardex K 15 (55 lb bag). A 120 sq ft room at 1/4 in average needs roughly 4–6 bags depending on the product, before waste.
How many bags of self leveling concrete do I need for 100 square feet?
At a 1/4 in average depth, 100 sq ft takes 5 bags of Henry 555, LevelQuik RS or Novoplan 2 Plus, or 4 bags of Ardex K 15, before any waste allowance. At a flat 1/8 in over the whole floor it’s 3 bags of the first three, or 2 bags of K 15.
How much does a 50 lb bag of self leveler cover?
For the two big 50 lb bags, LevelQuik RS publishes 46–48 sq ft at 1/8 in and Novoplan 2 Plus publishes 48 sq ft. Coverage halves each time depth doubles, so about 23–24 sq ft at 1/4 in and 11.5–12 sq ft at 1/2 in. Henry 555 comes in a 40 lb bag covering 43 sq ft at 1/8 in, and Ardex K 15 in a 55 lb bag covering 30 sq ft at 1/4 in.
Do I need primer for self leveling concrete?
All four products here require their own primer, and pouring without it risks pinholes and bond failure. Henry 555 requires Henry 554 (100–150 sq ft per quart), LevelQuik RS uses LevelQuik Primer (150–300 sq ft per quart on porous concrete), Novoplan 2 Plus uses Primer T (50–100 sq ft per quart), and Ardex K 15 uses P 51 (400–600 sq ft per gallon). Very absorbent concrete usually takes two coats.
How thick can you pour self leveling concrete?
Poured neat in one lift, Henry 555, LevelQuik RS and Ardex K 15 go to 1.5 in. Novoplan 2 Plus caps at 1 in. Henry 555 and K 15 reach 5 in when extended with washed 1/8–3/8 in pea gravel, aggregate no larger than 1/3 the pour depth. Henry 555 and LevelQuik RS feather to nothing at transitions and perimeters (a full leveling pour still needs 1/8 in over the high point). K 15 tapers only as thin as its sand allows.
How long before you can walk on self leveling concrete?
At 70 F, Henry 555, Novoplan 2 Plus and Ardex K 15 are walkable in 2–3 hours, and LevelQuik RS in 2–4 hours. Tile can go down in 6 hours on Henry 555 and K 15, just over 4 hours on LevelQuik RS, and 24 hours on Novoplan 2 Plus. Moisture-sensitive floors such as vinyl and wood wait 16 hours on the first three and 2–3 days on Novoplan 2 Plus at 1 in thickness.
How much water do you mix per bag?
It depends on the bag. Henry 555 takes 5 quarts per 40 lb bag, LevelQuik RS 5.25–5.75 quarts per 50 lb bag, Novoplan 2 Plus 5–5.28 quarts per 50 lb bag, and Ardex K 15 7 quarts per 55 lb bag. Measure it. Extra water weakens the floor, and a yellowish foam on the mix means it’s already overwatered.
Can you pour self leveler in two layers?
Yes, every product here allows a second lift. LevelQuik RS takes the second lift as soon as the first reaches walkable hardness, with a re-prime required if the first has dried more than 12 hours. Novoplan 2 Plus waits 1 day between lifts. A Henry 555 aggregate lift gets primed with Henry 564 mixed 1:1 with water after 12–16 hours, and a K 15 lift gets P 51 at 1:1 after its 16 hour drying time. Then the neat finish coat goes on.