Hey – slac
That really depends entirely on your sealer mix design. If you look at the material spec sheet for the sealer your using it will usually provide a chart that gives the gallons per square yard (or feet) based on several different mix designs. For example, take a look at the spec sheet for Gem Seal Polytar. You can visit their website to take a look at http://www.gemseal.net/SpecSheets/polytar.spec.pdf
You can also check out the sealcoating mix design formula at https://www.pavemanpro.com/wiki/Sealcoating_Mix_Design_Calculations.
Hope this all helps.
