Bigger Batch

Ok, I have a few 5 gal AG batches under my belt, in my belly to be exact. I was wondering how or if any rule of thumb apply to increasing my recipes to 10 gal.
I have the equipment for the volume of wort to boil 10 gal. I have Beersmith but it is of no help. I know to double my yeast for two 5 gal batches to ferment, but was wondering about my grain bill? Any suggestions? Thanks, Ben

It's not exact, but you would need to add approximately a third more of each grain. As for the hops, just bump them up to keep the ibu's the same.

Ok, thanks for the suggestion. I'll put my recipe together and get my kettles going... Thanks again.

Why the need for the extra 1/3 of grains? Does that hold true for a 15gal batch? 20gal? etc...

Just did a 10gal batch of a 5gal recipe that I've already done, made no changes to the recipe, and actually came out slightly better on OG.

Not sure, that's why I was looking for suggestions. My Beersmith calculates the 10 gal grain bill and doubles it from a 5 gal batch? I suspect your efficiency was much better with the 10 gal batch. Get's a bit confusing sometimes.