Auto-Fill a column with a range formula, and have the reference cells increase in increments relative to the range size

I'm trying to auto-fill a column with a formula =SUM(SHEET1!B5:B11) but it goes up in increments of 1 not 7, so the next row down says =SUM(SHEET1!B6:B12), whereas I want=SUM(SHEET1!B12:B18). (7 instead of 1). I would've thought there would be some ctrl shift combo to do this, but I cannot find anything searching online.