Why the calculator prices plumbing by the fixture
Most of the work on a bathroom follows the fixtures. Each toilet, tub or shower and vanity needs its own drain and vent, its own supply lines and shutoffs, and its own finish work. Counting fixtures gives you a quick, honest measure of job size that a homeowner understands too.
The fixture count is a starting point, not a flat rate. Moving a toilet 2 ft means cutting the floor and rerouting a 3 inch drain, which is far more work than swapping one in place. If your job is lighter or heavier than the example, change the hours per fixture, not just the count.
Where 41 labour hours on a 3-fixture bathroom come from
The example adds up to 41.25 labour hours, or 13.75 a fixture. About three quarters of that is hands-on plumbing by a two-person crew: shutting off and draining down, the drain and vent rough-in, new water lines, the rough-in inspection and the finish.
The other quarter is the work around the job that gets left off when plumbers quote from wrench time: looking at the job before quoting, pulling the permit, pickups, driving to and from the house each day, protecting the floor and cleaning up, testing the lines and the walk-through with the customer. At $70 an hour, those hours are worth more than $700 on this bathroom.
Parts are $492.60 at cost, or $164.20 a fixture, and the 35% markup turns that into $665.01. The permit, the van and the fittings the takeoff always misses go on as their own lines.
One fixture or four: the same rate, a different price per fixture
Fixed costs do not shrink with the job. Run the example with 1 fixture and it comes to $1,991, because the permit, the van and the missed fittings are still there. With 4 fixtures it is $6,254.02, or $1,563.50 a fixture.
That is why a small job priced at the bathroom's per-fixture rate loses money, and why the $250 minimum exists. A short service call that works out to $180 still pays $250 for the van, the drive and the paperwork.
The rate matters as much as the count. At $85 an hour instead of $70, the same 3-fixture bathroom is $5,575.51.
What the quick plumbing price leaves out
The $70 break-even rate is the example shop's $69.95, rounded. Yours comes from your wages, payroll costs, vans, insurance and the hours your plumbers can actually bill. The plumbing hourly rate page shows how the example gets there, and the true hourly rate calculator does it with your numbers.
The spreadsheet prices each phase and each part from your price list, adds a safety cushion and sales tax, lists exclusions and prints a customer quote. Its version of this bathroom is $5,451 with tax. The plumbing pricing guide walks through it. Anything found once the walls are open belongs on a written change order, not in this number.