Rammed Earth Wall Calculator

Wall Volume comes from Wall Length, Wall Height, and Wall Thickness multiplied together, and it feeds both Loose Soil and Cement Bags in direct proportion -- but Loose Soil isn't a 1:1 match to finished volume, because loose soil compacts roughly 30-40% when rammed, so the calculator uses a 1.4x multiplier: 300 cu ft of finished wall volume needs about 420 cu ft (15.6 cu yd) of loose soil to start with. Form Placements and Lifts per Section come from a completely different pair of inputs -- Lift Height and Form Length -- that never touch soil volume at all: doubling Lift Height from 6 in to 12 in halves the number of lifts (and therefore halves total form placements) without changing the wall volume or soil quantity one bit, since those are purely geometric outputs describing the construction sequence, not the material takeoff.

Cement Bags assumes an 8% stabilizer ratio by weight against a 110 lb/cu ft soil density, rounded up to 94 lb bags -- a stabilized mix, common in wetter climates or where code requires it, rather than the unstabilized rammed earth some builders use in arid regions. At the default 20 ft by 10 ft wall, 18 in thick, that's 300 cu ft of finished wall, roughly 15.6 cu yd of loose soil, and 29 bags of cement.