Center-drain shower pan geometry and the four-plane mortar volume formula
A center drain slopes from all four sides, so the bed holds more mortar than “area × average depth.” This calculator uses the four-plane formula.
What this diagram shows
Top-down view of a square shower pan whose floor slopes from all four walls down to a center drain, forming four triangular planes. The mortar volume is length times width times the quantity depth-at-drain plus slope times the sum of length and width divided by six. A simple area-times-average-depth shortcut underestimates the sloped volume by up to about 25 percent.
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Floor Mud Calculator
Free floor mud / deck mud calculator. Bag count, mortar bed volume & cement-sand ratios for shower pans, pre-slope & flat floors per ANSI A108.1A.
