Profit shown is what you make if all four legs land, with the 25% boost paid on top; if any leg loses you finish on about £0. The calculator opens with Bally’s normal acca odds, so its “all land” line shows a small loss: the boost covers it. Max stake £20; the boost stops growing once the acca’s odds pass 41.0. Prices can sit above Bally’s real ones, so check the boosted odds on Bally’s slip before you bet.