Mixed gallons and concentrate gallons are different shopping lists
A wash thinned three parts water to one part paint puts four gallons of liquid on the drop for every gallon you bought. Estimating the wash in mixed gallons and then going to buy that many is how a show ends up with eleven gallons of a colour it needed three of. The calculator carries both numbers all the way through: mixed gallons tell you how many buckets you will be filling and how long the day is, concentrate gallons tell you what to order.
The gap between them is not uniform across a set. Base coats often go on straight or barely thinned, so their two numbers are close. Washes, glazes and spatters are usually thinned hard, so a layer that looks expensive in mixed gallons can be almost free in concentrate. That inversion is the single most useful thing on this page.
Partial coverage is what makes scene paint cheap
A spatter that reads solidly from the back of the house might land on a quarter of the surface. Twenty-five per cent coverage over a 960 square foot drop is 240 square feet; two passes at 250 square feet a gallon is 1.92 gallons of mixed paint, and under half a gallon of concentrate once it is thinned three parts water to one. The base coat under it, at two coats and 160 square feet a gallon over the whole face, is twelve gallons flat.
So the layer that takes all the time on the paint deck takes almost none of the budget, and the layer that goes on in an hour with a roller takes nearly all of it. Scenic budgets that treat every layer as a full coat over the full area come out four or five times high, get cut, and then the base coat runs out on the second drop.
Measure the rate on the actual goods
The coverage number on a container was arrived at on a sealed, smooth, absorbent-in-a-known-way test surface. Raw muslin is none of those things. Unsized cloth takes the first coat into the weave and can come in at half the stated rate or worse; the second coat on the same cloth, now sealed by the first, can beat it. Hard scenery that has been primed behaves like a wall. A used drop that has been painted over four times behaves like plastic.
The cheap way to find out is to paint a panel of the real material, note the area and what came out of the bucket, and divide. Ten minutes of that turns every other number on this page from a guess into an estimate. It is also the only way to catch the case where the piece needs a size coat first, which does not read as paint on the finished drop but does read on the invoice.
What the sheet does not settle
Nothing here speaks to what a venue requires of scenic materials, what a given paint or treatment does to a material, or how any of it should be applied. Those come from the venue and from what is written on the container. Paint and solvent in a closed shop is a real hazard with a real name and no procedure offered here.
Questions people ask
How much paint does a stage drop take?
Take the face area, divide by the coverage rate you measured on that cloth, and multiply by the number of coats — then handle the treatments separately, because they land on part of the surface rather than all of it. A 40 by 24 foot drop at two base coats and 160 square feet a gallon is twelve gallons of mixed base, and a spatter and a dry brush over it add about two more gallons mixed — under a gallon once the dilution is taken back out. The base coat is nearly always the whole story on a drop.
Why does raw muslin take so much more paint than a wall?
Because there is no film to stop it. The first coat on unsized cloth goes into the weave rather than onto it, and part of what you paint on comes out the other side or stays in the fibre. The second coat sits on a surface the first one made and behaves far more like paint on a wall. This is why a two-coat estimate at a single rate is always wrong on soft goods, and why the rate on this page is something you measure rather than something it assumes.
How do I estimate paint for a spatter or a scumble?
Estimate the fraction of the surface that actually receives paint, not how far the effect reads. A spatter that looks continuous from row K is often twenty to thirty per cent coverage; a heavy scumble might be sixty. Multiply that fraction by the face area, then apply a coverage rate measured for that technique. Then divide by the dilution, because these layers are usually thinned hard and the concentrate figure is a fraction of the mixed one.
Should I include a size coat in the estimate?
If you are sizing, yes, and it belongs as a layer of its own with its own rate and dilution, because it behaves nothing like the base coat that follows. Size goes on thin, covers the whole face, and its whole job is to change the coverage rate of everything after it — which is exactly why estimates that leave it out come in low twice over, once for the size itself and once for the base coat that was measured on already-sized cloth.
How much extra should I allow for what is left in the bucket?
The default here is ten per cent, which covers what clings to the bucket, the roller, the brushes and the tray, plus the bit at the bottom that skins over between calls. It goes up when you are mixing a lot of small custom colours, because each one leaves its own residue and none of it can be combined. If you are mixing eight colours for a treatment, budget the waste per colour rather than across the total.