Bought loose, measured compacted
This is the whole subject. A rammed earth wall is drawn, specified, priced and argued about in compacted volume, and every cubic foot of it arrives, gets stockpiled, gets wheeled and gets shovelled loose. The ratio between those two states is a property of your particular mix at your particular moisture content, and it does not come from a book. It is measured by filling a form to a marked depth, ramming it, and measuring what is left.
Say the ratio is 2.4. A 20 by 8 foot wall at 18 inches thick with one 4 by 5 foot opening is 210 cubic feet of wall, which is 7.78 cubic yards. The material for it is 18.67 cubic yards. That is not a waste allowance and it is not an error — it is the same earth in two different states, and the second number is the one the truck, the stockpile area and the barrow count all run on.
The same ratio is what tells the crew how deep to fill. A four inch compacted lift at 2.4 means shovelling in 9-5/8 inches of loose mix. Mark that on the inside of the form. A crew judging it by eye drifts one way or the other, and the drift shows up as lift lines at uneven spacing on the finished face, which is a permanent feature of the wall.
The unit of work is a lift in one form position
Wall volume is the wrong unit for planning the day. What actually happens is that a form sits somewhere on the wall and a sequence of lifts goes into it, and then the form moves. So the count that matters is lifts multiplied by positions along the run, and each of those is a fill and a ram taking a fairly predictable amount of time. The forms then get struck, moved and reset once per position and once per climb.
Splitting the hours between ramming and form handling is worth doing before the job rather than after, because they respond to different things. A faster tamper reduces the first number and does nothing to the second. Longer or taller panels reduce the second and do nothing to the first. On a small wall with short forms, form handling is often the larger of the two, which is not the intuition people arrive with.
Openings take material out, not lifts
A window in a rammed earth wall removes volume but the lifts still run past it on both sides, so the lift count does not fall. That is why this page deducts opening area from the volume and leaves the lift count alone. The practical consequence is that a wall with a lot of glazing is not proportionally faster to build, because the number of times a form gets filled and rammed barely changes.
What is not on this page
No lift thickness, no compaction standard, no moisture target, no stabiliser dose, no strength, no wall height limit and no verdict on the ratio you entered. Those come from a mix design and from the engineer of record. Rammed earth sits outside the prescriptive path in most adopted codes, so permitting usually runs through an alternative materials review and often requires a stamp.
Two hazards stated and not managed here. Rammed earth forms take a heavy repeated dynamic load from the tamper, and a form failure while somebody is standing on the wall ramming is a serious event; the form design and the bracing belong to whoever designed them. And earth, lime and cement all raise silica dust when they are handled dry, while lime and cement are caustic on skin and in eyes. The safety data sheets and the applicable rules govern that, not a calculator.
Questions people ask
How much loose material does a rammed earth wall take?
The compacted wall volume multiplied by your own loose to compacted ratio. On the defaults here the wall is 210 cubic feet, 7.78 cubic yards, and the loose mix behind it is 18.67 cubic yards at a ratio of 2.4. There is no standard ratio to quote because it depends on the grading of your mix and the moisture you are ramming at. Measure it in a form once and the whole job scales off it.
How deep do I fill the form for a four inch lift?
The compacted lift thickness times your ratio. At 2.4 a four inch compacted lift means filling to 9-5/8 inches loose. Marking that depth inside the form is worth the two minutes, because judging it by eye drifts, and uneven lift spacing is visible on the finished face for the life of the wall.
What lift thickness should I use?
Whatever the mix design or the engineer specifies, and this page supplies none. Lift thickness interacts with the compaction energy available, the mix and the wall thickness, and it is a specification item rather than a preference. The calculator takes the figure you were given and works out the lifts, the loose depth and the barrow loads that follow from it.
Why does form handling take so much of the time?
Because the forms move once for every position along the run and once for every climb, and a strike, move, reset and re-plumb is a slow operation compared with filling and ramming a single lift. On short panels the setting count multiplies quickly. The calculator prints form handling as a share of the total so you can see whether longer or taller panels would change the job more than working faster would.
Does this tell me whether the wall is strong enough?
No. It counts lifts, volume, form settings and hours for a wall somebody else has designed. Rammed earth is outside the prescriptive path in most adopted codes, which usually means an alternative materials review and frequently an engineer stamping the wall. Strength, reinforcement, thickness, height and the mix design all come from that process.