That is the easiest way to do it and plenty of people use this method. I think I remember reading that your hop utilization will decrease slightly, but I have no info to back that up.
Yep. I'd second checking your IBUs on an online hop calculator. Plan on boiling off a gallon to a gallon and a half from your boil.
Usually the one gallon commercial recipe uses 1 oz multiplication of hops, because of packing less then one Oz will not cost the same as the hops. When I started one gallon recipe , on my second batch I cut the hops by 1/3, when I start brewing 5 gallons I realize that 5 gallon batches can use less then one OZ hops. To summarize all that use brewing software , plus use common sense and adjust any recipe with your brewing software.
Easiest way to do this is calculate your ingredients based on a percentage. Then as you scale your recipes the percentages will not change, but the total amount will.
You specify your target 5 gal batch as being all grain. Was your one gal batch extract? This could be a very different case.
No it was all grain. 2 1/4 pound rather 2 row 1/4 pound Munich malz 1/8 pound crystal 60 1/2 ounce citra at boil 1/2 ounce Amarillo,citra,simcoe @ 30 mins 1/2 ounce Amarillo,citra,simcoe @ 15 mins 1/2 ounce citra dry hop
I have scaled from 1:5 and 5:1 gallons an used linear conversion both ways. You will be a little off on hop utilization but not so much you should tear apart the recipe and recreate it to scale up or down.
