So I’ve been following the article on here for converting, but I’m curious what to do in the instance that it’s either not one of the Efficiency % on there or is not an even round weight. If it’s 6lbs, 5.6oz do I just round up to 7lbs? and do I just go with the next highest percentage? or down to the closest on the down side?
6 lbs 5.6 ounces is 6 + 5.6/16 lbs = 6.35 lbs. That is the number I would use.
Regarding efficiency: that’s the kicker. You might just assume 70%. But, that could be wrong. You could enter the recipe into an online calculator (like BrewersFriend) with the grain amounts provided in the recipe and the batch size. Then change the efficiency setting up and down until the calculator predicts the original gravity (OG) given with the recipe. That would be the efficiency to use.
If you know the PPG of the extract you can just use some math rather than the tables.
Morebeer.com LME is 35 PPG.
LME weight = grain weight * 36 * efficiency / 35
If your converting for DME, use 43 PPG (Briess DME is 43 PPG). So, change 35 to 43 in the equation above.
DME weight = grain weight * 36 * efficiency / 43
In the equations above 36 is the PPG for generic base malt. It should be good enough. Some base malts are a bit higher or lower.
I think this is the best way to do it. I replace the base malt with the appropriate DME (I use Briess Pilsen or Extra Light DME unless I have a specific reason to use something else), and steep the specialty grains. I don’t bother with LME for converting recipes; with DME I can weigh out the exact amount).