Estimate a rectangular mortar bed over a flat base with a single slope toward the drain. Enter the slope specified for your project. The initial values are an example.
Diagram not to scale.
Slope and mortar estimate
- Rise at the far edge above the drain: 1 in.
- Mortar thickness at the far edge: 2 in.
- Mortar volume before waste: 1.5 ft³
- Mortar volume with waste: 1.65 ft³
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How it works
Measure the horizontal run to the drain and the section width.
Enter the specified slope and mortar thickness at the drain. Fractions such as 1/4 are accepted.
Check the rise, far-edge thickness and mortar volume. Enter the bag yield to estimate how many bags to buy.
Frequently asked questions
How do I calculate shower floor rise?
Multiply the run in feet by the specified slope in inches per foot. A 4-foot run at 1/4 inch per foot rises 1 inch at the far edge.
Does the volume estimate work for a center drain?
The volume models one rectangular section over a flat base with a uniform slope in one direction. A floor that slopes toward a center drain requires its own geometry.