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Henry 555 LevelPro Coverage Calculator: How Many 40 lb Bags?
Enter your floor area and the average pour thickness to see how many 40 lb (18.1 kg) bags of HENRY 555 LevelPro to buy. Henry's data sheet gives one coverage figure, 43 sq ft per bag at 1/8 inch; the calculator scales that to your thickness, so 1/4 inch works out to 21.5 sq ft per bag. The numbers come from the W.W. Henry Company technical data sheet dated 2025-05-15.
HENRY 555 LevelPro coverage
| Thickness | US | Metric |
|---|---|---|
| 0.125 in (3.2 mm) | 43 sq ft | 4 m² |
| 0.25 in (6.4 mm) | 21.5 sq ft | 2 m² |
| 0.5 in (12.7 mm) | 10.8 sq ft | 1 m² |
| 1 in (25.4 mm) | 5.4 sq ft | 0.5 m² |
| 1.5 in (38.1 mm) | 3.6 sq ft | 0.3 m² |
Source: The W.W. Henry Company Technical Data: HENRY 555 LevelPro Self-Leveling Underlayment, Dated 2025-05-15 (file posted October 2025), read 2026-10-16.
How the calculation works
bags = area × (1 + waste ÷ 100) × thickness ÷ (coverage at reference thickness × reference thickness), rounded up
Self-leveler volume scales with thickness: twice as thick needs twice as many bags. Low spots in the floor add to the real average thickness, so measure the deepest point and the average before you pour.
Worked example
A 200 sq ft floor poured 0.25 in thick with 10% extra: 220 sq ft to cover. One bag covers 43 sq ft at 0.125 in, so at 0.25 in it covers 43 × 0.125 ÷ 0.25 = 21.5 sq ft. 220 ÷ 21.5 = 10.23 bags, so buy 11 (440 lb).
HENRY 555 LevelPro key specs
| Product type | Self-leveling underlayment |
|---|---|
| Bag size | 40 lb (18.1 kg) |
| Mixing water per bag (max) | 5 US qt (4.73 L) |
| Thickness range | 0.125–1.5 in |
| Coverage (data sheet) | 43 sq ft (4.0 m²) per 40 lb (18.1 kg) bag at 1/8" (3 mm); scaled: 21.5 sq ft at 1/4", 10.75 at 1/2", 5.4 at 1" |
| Mixing water | 5 US qt (4.73 L) per 40 lb bag; water in the bucket first; do not overwater (yellowish foam means too much water) |
| Mixing | 1/2" heavy-duty drill, at least 650 RPM, mixing paddle; mix 2 minutes until lump-free |
| Thickness | at least 1/8" over the highest points of the subfloor; up to 1 1/2" neat over large areas; up to 5" with 1/8"–3/8" pea gravel; may be featheredged to meet existing elevation |
| Flow time | 10 minutes at 70°F (21°C) |
| Walkable | 2–3 hours at 70°F |
| Install floor covering | ceramic tile in as little as 6 hours; all other floor coverings after 16 hours |
| Primer | HENRY 554 LevelPro Underlayment Primer (1:1 with water on concrete; undiluted on wood and adhesive residue; also required on deglazed ceramic tile); the cover also reminds you of HENRY 564 primer, which the sheet uses 1:1 between an aggregate fill and the neat coat |
| Substrates | concrete (old or new), cementitious terrazzo, wood subfloors with metal lath, ceramic tile, cutback and other non-water-soluble adhesive residue on concrete |
| Temperature | subfloor thoroughly dry and at least 50°F (10°C) before priming and installation |
| Use | interior floors only, under a floor covering; Portland cement-based; made in the USA |
| Warranty | one year from date of purchase against breakdown from a manufacturing or formulation defect, subject to Henry's exclusions |
What Henry 555 LevelPro is for
HENRY 555 LevelPro is a Portland cement-based self-leveling underlayment from the W.W. Henry Company, the flooring adhesive and prep brand that is part of the ARDEX group and shares its Aliquippa, Pennsylvania address. You mix it with water, pour it, and spread it so it settles into a smooth, flat surface before the finished floor goes down. It is sold in 40 lb bags at home centers and flooring stores, which makes it one of the self-levelers DIYers meet most often.
Henry describes it as an interior product for smoothing floors over properly prepared concrete (old or new), terrazzo, wood, ceramic tile and adhesive residue on concrete. It is meant to sit under a floor covering. Henry pitches it for both glue-down and glue-less (floating) floors, and says tile can be set on it in as little as 6 hours and other floor coverings after 16 hours.
How the calculator works out bags
Henry's data sheet gives a single coverage number: 43 square feet per 40 lb bag at 1/8 inch thick. That works out to about 0.45 cubic feet of mixed material per bag. A bag makes a fixed volume, so the area it covers falls in direct proportion to how deep you pour. Double the depth to 1/4 inch and a bag covers about 21.5 sq ft; at 1/2 inch it is about 10.75 sq ft, and at 1 inch about 5.4 sq ft.
The calculator takes your floor area, adds the waste allowance you choose, multiplies by your average thickness to get a volume, and divides by the volume one bag makes. Bags are always rounded up. Using the worked example on this page, a 200 sq ft room plus 10% waste at an average of 1/4 inch needs 220 ÷ 21.5 = 10.2 bags, so you would buy 11 bags, or 440 lb of powder.
Two practical points. First, enter the average thickness, not the deepest dip. A laser level, or a long straightedge and a tape measure, will show you where the low spots are; estimate the average depth across the room, or split it into zones and run the calculator once for each. Second, the bag size is smaller than many competitors. ARDEX K 15 comes in 55 lb bags and most others in 50 lb, so a "bags per room" figure from another product will undercount Henry 555. Compare by area per bag at the same thickness, which is what the self-leveler hub on this site does.
Thickness range
Henry asks for at least 1/8 inch over the highest points of the subfloor to get the full smoothing effect. That is why the calculator's lower limit is 1/8 inch. The material can be featheredged to meet an existing floor at a doorway, but a featheredge is a transition detail, not a thickness you can plan a whole floor around.
The upper limit is 1 1/2 inches neat over large areas. Deeper than that, up to 5 inches, Henry says to extend the mix with washed, well-graded 1/8 to 3/8 inch pea gravel: mix the 555 with water first, then add 1 part aggregate by volume and keep mixing until the stone is coated. The stone must not be bigger than one third of the pour depth, and Henry says not to use sand. If the gravel is wet, cut back the water. Gravel stiffens the mix, so you may need a neat top coat: let the first layer dry 12 to 16 hours, prime it with HENRY 564 mixed 1:1 with water, let that dry for 3 to 24 hours, then pour the neat coat. The calculator does not model aggregate, so above 1 1/2 inches it shows a warning and its bag count should be treated as an upper bound.
Preparation and priming in brief
Every surface must be sound, solid, clean and free of oil, wax, grease, asphalt, paint, patching and curing compounds or anything else that could stop the bond. Henry says to remove contaminants mechanically, for example by grinding, and not to acid etch or use solvents. The subfloor must be thoroughly dry and at least 50°F (10°C) before you prime and pour.
- Concrete and cementitious terrazzo: prime with HENRY 554 LevelPro Underlayment Primer diluted 1:1 with water. If the primer dries in under 10 minutes the concrete is very absorbent; prime first at 3 parts water to 1 part primer, let it dry 1 to 3 hours, then apply a 1:1 coat and let it dry 3 to 24 hours.
- Wood: at least 3/4 inch tongue-and-groove APA rated Exterior plywood, an OSB equivalent, or solid nailed hardwood, sanded to bare wood and re-nailed where boards move. Prime undiluted, dry 12 to 24 hours, then staple 3.2 or 3.4 galvanized expanded diamond metal lath roughly every 6 inches with about 1 inch overlaps.
- Cutback adhesive on concrete: wet-scrape the old adhesive down to a stain-thin layer, then prime undiluted and let it dry 16 to 24 hours.
- Ceramic tile: mechanically roughen to remove the glaze, prime, and let it dry 12 to 24 hours. Henry asks you to call its technical department for other tile types.
Budget the primer time into your schedule. On wood and adhesive residue the overnight primer dry is often longer than the self-leveler's own wait before tile.
Mixing and timing
Each 40 lb bag takes 5 US quarts (about 4.73 L) of water. Put the water in a 5 gallon bucket first, then add the powder while mixing with a paddle on a 1/2 inch heavy-duty drill running at 650 RPM or faster, and mix for 2 minutes until there are no lumps. Henry's warning is in capitals for a reason: do not overwater. A yellowish foam on the surface means the mix has too much water, which weakens the underlayment.
The mix flows for about 10 minutes at 70°F, so have the area dammed off and the next bucket ready before you start. Pour, spread with a gauged spreader or rake (a flat trowel for small areas), and smooth straight away. Henry says to work continuously through the whole pour, and suggests athletic shoes with plastic cleats so you can walk in the wet material on larger floors without leaving marks. You can walk on it after 2 to 3 hours at 70°F, set ceramic tile after about 6 hours, and install other floor coverings after 16 hours. Clean tools with water before the material sets, and do not pour leftover material down a drain.
FAQ
How much does a 40 lb bag of Henry 555 LevelPro cover?
The W.W. Henry data sheet gives one figure: 43 sq ft (about 4.0 m²) per 40 lb bag at 1/8 inch thick. The same volume spread twice as deep covers half the area, so a bag covers about 21.5 sq ft at 1/4 inch, 10.75 sq ft at 1/2 inch and about 5.4 sq ft at 1 inch.
How much water do I mix with a bag of Henry 555?
Henry says to add one 40 lb bag to 5 US quarts (about 4.73 L) of water. Pour the water into the bucket first, then add the powder while mixing with a paddle on a 1/2 inch heavy-duty drill running at least 650 RPM, and mix for 2 minutes until lump-free. Do not overwater: a yellowish foam on the mix is the sign of too much water.
What is the minimum and maximum thickness for Henry 555 LevelPro?
Henry asks for at least 1/8 inch over the highest points of the subfloor to get full smoothing, and allows up to 1 1/2 inches neat over large areas. It can be featheredged where it meets an existing floor. For pours deeper than 1 1/2 inches, up to 5 inches, Henry says to add 1 part washed 1/8 to 3/8 inch pea gravel by volume, never sand.
How long before I can walk on it or tile over it?
At 70°F (21°C) you can walk on Henry 555 LevelPro after 2 to 3 hours. Ceramic tile can go down in as little as 6 hours, and Henry says to wait 16 hours for all other floor coverings. Cooler rooms and thicker pours take longer, so treat these as the earliest times, not a schedule.
Can I pour Henry 555 over a plywood subfloor?
Yes, with extra steps. The wood must be at least 3/4 inch tongue-and-groove APA Exterior plywood, OSB equivalent, or solid nailed hardwood, sanded to bare wood and rigid. Prime it with undiluted HENRY 554 primer and let it dry 12 to 24 hours, then staple 3.2 or 3.4 galvanized expanded diamond metal lath about every 6 inches, overlapping pieces about 1 inch, before you pour.
W.W. Henry Company and HENRY 555 LevelPro are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.