What area does a heated-floor quote count?

Heated-floor estimates can be hard to compare if one quote counts the whole bathroom and another counts only the area where heating will actually go. The main walking area might be heated while the footprint beneath a vanity is left out; extending the layout beneath it, or into a shower, could change the scope.

When you request quotes, do installers spell out the heated square footage separately from the room’s total floor area? I’d also want to see floor preparation, the thermostat, and any electrical work itemized rather than buried in a single installation figure. For a hypothetical bathroom with different proposed coverage areas, what details have made the biggest difference in getting comparable estimates?