A calculator can give the right answer and still encourage the wrong decision.
On OwnerEdge, I separate gross platform fees from the net benefit of a direct booking.
Hypothetical example: a $700 stay avoids a 15% fee ($105), but a $70 discount, $18.90 payment fee and $5 in other costs leave $11.10 extra. Marketing and admin can reduce that further.
The design choice: show editable assumptions and the net comparison together, rather than lead with a big ‘fees saved’ number. Rates vary; this is an estimate, not a profit forecast. Only compare bookings you’re permitted to take directly.