Fvstringpicker is very correct. You need to calibrate the sprayer to your own application rate. It doesn't help to know how many ounces of chemical per thousand if you don't know how many gallons per thousand you spray at.
Does it take you 1 gallon to cover 1000 ft², or 2 gallons, or what? And if you use different spray tips, your application rate will change. If you use higher pressure, your application rate will change. If someone else uses your sprayer, you will have to calibrate the sprayer to his rate (maybe he walks faster or slower), or you will have to teach him to spray at exactly your rate.