Let's say an F/A-18C returns to land after expending some payload. Fuel burned and weapons released made the plane lighter. I guess the aircraft computer can tell the pilot the actual weight of the fighter on one of the displays. With this information, does the pilot use a chart or computer to calculate the correct speed for landing or is there a rule of thumb?
In the F-4, we had a base speed to use for each aircraft landing configuration, to which we would add 2 knots for each 1000 pounds of fuel. If we still had any significant external stores hanging on the plane we would treat as that as additional fuel.
But when we were actually flying the approach, we had an aural tone in our helmet (headset) that told us exactly what the AOA was, it went to a steady tone when we were at optimum landing (approach) AOA.