Unit profit from cost, commission, shipping and returns, with the break-even price and ROAS
A return refunds the price and the commission while the unit comes back to the shelf, so revenue and cost both scale with the share of orders kept; shipping and ad spend do not. Break-even ROAS uses the contribution before ads — every unit of ad spend has to bring back that much revenue to wash out. Fee schedules and return rates move, so use your own back-office numbers.