Self-Leveling Underlayment Calculator
Estimate bags of self-leveling underlayment from the pour area and minimum thickness, using each bag’s cubic-foot yield.
How it works
volume (cu ft) = area × (thickness ÷ 12) · bags = ceil(volume ÷ bag yield)
Self-leveling underlayment is a full pour to a minimum thickness, so its volume is the area times the poured thickness in feet, with thickness entered in inches and divided by 12. Each 50 lb bag yields roughly 0.45 cubic feet mixed. Because SLU flows to find its own level, use the average poured thickness across the whole area, and respect the product’s minimum — pouring thinner than spec risks cracking.
Worked example
A 300 sq ft floor poured at an average 1/4 inch: 300 × (0.25 ÷ 12) = 6.25 cubic feet. At 0.45 cu ft per bag that is 14 bags, or 15 with waste — each bag covering about 22 sq ft at that thickness.
Frequently asked questions
What is the minimum thickness for SLU?
Most self-levelers have a minimum around 1/8 to 1/4 inch at their thinnest and a maximum per lift of an inch or more. Below the minimum they can crack or fail to flow, so plan the pour to keep the whole surface above spec even at its high spots.
How is it different from a leveling compound?
A patch or leveling compound is troweled and can feather to a zero edge; self-leveling underlayment is poured and spreads itself to a flat plane at a minimum thickness. Use SLU when you need a whole floor dead flat, and a patch compound for local dips.
Do I have to prime and dam the edges?
Yes — SLU needs its specified primer for bond and is liquid enough to run through any gap, so seal penetrations and dam doorways. That does not change the bag count but is essential to a successful pour.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.