Coverage Estimates
  Film Forming Sealer
1st Coat*
Penetrating Sealer
1st Coat*
Concrete 200-300 ft per gal. 150-250 ft. per gal.
Dense Material like Slate 250-350 ft per gal. 300-500 ft per gal.
Porous Materials like Saltillo 150-200 ft per gal. 150-200 ft per gal.

* Coverage will vary widely by porosity. A second coat will go about 50% further.