A load paying $2.60 a loaded mile with 180 deadhead miles in front of it is really 520 miles of work for $1,040: $2.00 a total mile, not $2.60. Then the truck takes its cost per mile out of that, and the hours — drive time plus the two dock waits — decide whether the day was worth it at all. Two loads with the same headline rate can differ by several dollars an hour depending on where the deadhead is and how long the docks take, which is why this tool ranks on net profit per hour, not on the rate.
Where the counter-offer comes from: the rate that makes your minimum is (cost per mile + minimum profit per mile) × total miles − extras, and the rate that makes your minimum per hour is minimum per hour × hours + cost per mile × total miles − extras. Whichever is higher is the number to say out loud. Brokers negotiate on rate per mile; you negotiate on profit per hour.
Information, not financial advice. Rates, fuel surcharges, accessorials and detention terms are contractual — read the rate confirmation, all of it, before the wheels turn.