Why floor area is only the yardstick for a bathroom gut
A bathroom's cost sits in the fixtures, the tile and the trades, not in the floor. The calculator still asks for square feet because it is the one size every bath has, and it lets you compare jobs: the example works out to $464.94 a square foot, 2.9 crew hours a square foot and $75.17 of materials a square foot.
Treat those per-foot figures as averages for this kind of bath, not as rates to quote from. A 40 sq ft bath with a tiled shower and niche needs more hours per foot than one with a tub surround. Change the hours to match the scope, not the size.
Plumber, electrician and permit: three boxes worth $3,770
The extras are the subs and the permit, paid once per job. In the example they total $3,770, more than the fixtures. They get profit on top like everything else, because you carry the scheduling, the callbacks and the risk if a sub runs late.
Paste each sub's quote in as written. If the plumber has to move the drain and the quote goes from $2,600 to $3,400, the bathroom goes from $18,597.79 to $19,557.79. Anything found after demo, like rot under the toilet, belongs on a written change order, not in the starting price.
A 60 sq ft bath with a moved drain
Here is the same build-up on a larger room with the bigger plumbing quote:
| Bathroom | Crew hours | Price | Per sq ft |
|---|---|---|---|
| 40 sq ft, example | 116 | $18,597.79 | $464.94 |
| 60 sq ft | 174 | $25,634.69 | $427.24 |
| 60 sq ft, plumber at $3,400 | 174 | $26,594.69 | $443.24 |
The larger room scales hours and materials by 1.5, which is a fair first guess for tile and board but too much for the toilet and vanity, which you buy once. If the larger bath keeps a single vanity, lower the materials per square foot and the price comes down. The calculator never knows what is in the room. You do.
What the bathroom spreadsheet adds to reach $22,784
Every bathroom total above runs on $70 an hour, the example renovation company's break-even with its truck, trailer, insurance and office. Find your own with the free hourly rate tool before you quote a gut from this page.
The spreadsheet then counts what this page leaves out on a bathroom: the truck and tile saw by their running hours, waste on tile and board, the dump runs and their fees, floor protection, an allowance for rot and a markup on the subs. It lists every fixture and allowance from a price list and prints a customer quote that shows the allowances without your hourly rate. That is why the full version comes to $22,784.
For the reasoning behind each line of that quote, and how a small bath ends up priced high per foot, read the bathroom remodel pricing guide.