There is a “time honored” basic math formula that is generally accurate for shots of 100 yds or more - 30/40 rough, distance times 1.1, 40/50 rough, distance times 1.2. These work fairly well for basic shot setup, but you also have to factor in elevation, roll out, wind. Less than 100 yds, depending upon your wedges you can be fairly accurate with + 2 - 4 yds for 30/40; 40/50 takes some practice because results are not always consistent and vary from situation to situation. For up close shots at the green, the flop works best as it will stop the ball fairly well. Classic example, WC hole 13 with either pin, the upper one especially. Not uncommon to be long off the green in the 30/40 rough. A pitch will land you close, but will not stop. With a proper set up, the flop will. Good idea to map your wedges for flops from the rough. Good place to practice hitting from 40/50 to the green is Merion #11. Hit your tee shot over the creek into the deep spinach. Then use your 64° wedge and practice hitting out.