Whether the layout changes
Keeping the toilet, tub and vanity where they are is the simplest case. Moving a drain or a supply line means opening the floor and sometimes the wall below, and that adds time.
Ask what the quote assumes about the layout, and what it would cost to change it.
Tile and finishes
Large-format tile, natural stone and detailed patterns take longer to cut and set than a simple tile. A tiled floor and walls are more labor than a prefabricated surround.
The quote should say which tile is included, or give an allowance you can adjust.
What is behind the walls
Old plumbing, outdated wiring and soft subfloor often turn up once the room is opened. A careful contractor tells you how those will be handled and priced before they happen.
Ask what happens if something unexpected is found, and who decides.
Glass, tubs and fixtures
Frameless glass, freestanding tubs and designer fittings cover a wide range. Two quotes that look different may simply assume different fixtures.
Compare the fixture lists before you compare the totals.
Access, schedule and permits
A second-floor bathroom, a tight hallway or a house with one bathroom changes how the work is planned. Permits and inspections add steps that should be written into the schedule.
A clear schedule is a sign the quote is thought through.
