You said you had 32.75 of H2O in your reaction that you can substitute with DNA (actually 34.75). And you need 50ul to have 1ug. So I calculated which overal reaction volume is proportionate to using at least 50ul of H2O. That is (50/34.75)/50 = 71,94.... So round off to 72 and that is 144% of your original volume.