Estimate dry-pack deck mud for a shower pan, mortar bed, or floor.
Enter the area you're packing and the average thickness of the mud bed to get the volume, the number of pre-blended 60-lb bags, and a from-scratch sand-and-cement breakdown. For a sloped shower pan, use the average thickness across the pan — not the deepest point at the perimeter.
How it works
Deck mud (dry-pack mortar) volume is area × average thickness, plus a waste allowance for packing and screeding. A 60-lb bag of pre-blended sand/topping mix yields about 0.5 cubic feet packed, so the calculator divides total volume by 0.5 and rounds up. If you mix your own, deck mud is sand and portland cement at 5:1 by volume (4:1 for a richer mix); the cement fills the voids between sand grains, so finished volume tracks the sand volume, and you add roughly one part cement for every four or five parts sand.
Frequently asked questions
How much deck mud do I need?
Multiply the area by the average thickness in feet to get cubic feet, then divide by about 0.5 for 60-lb pre-blended bags. A 3 × 3 ft shower pan at 1.5 inches average needs roughly 1.2 cubic feet — about 3 bags with a little waste.
What is the mix ratio for deck mud?
Standard deck mud is 5 parts sand to 1 part portland cement by volume; 4:1 gives a slightly richer, stronger mix. It's a stiff, barely-damp “dry pack” — it should hold a shape when squeezed, not flow. Pre-blended sand/topping mix already has the cement in it.
How thick should a deck mud bed be?
A mortar bed is usually 1.25 to 2 inches thick, and a shower pan slopes about 1/4 inch per foot toward the drain — so the bed is thinner at the drain and thicker at the walls. Use the average thickness for the estimate, and keep a minimum of about 1 inch at the thinnest point.
Can I use deck mud over a pre-slope and liner?
Yes — that's the classic shower build: a sloped pre-slope of deck mud, the waterproof liner over it, then the top deck-mud bed for the tile. Calculate each layer's volume separately and add them, since both layers are deck mud.
Is this calculator free and private?
Yes. Every CubicCabin calculator runs entirely in your browser, so the numbers you enter are never uploaded or stored. There's no sign-up, no limits, and it keeps working even if you lose connection after the page loads.