Replacing grain with extract - conversion help

Hey all,

So I've read that when you replace malted grain with extract, there is a pound to pound conversion. The numbers I've read at .65 for DME and .75 for LME (can anyone vouch for these?) but my question is do I need to use a multiplier for tun efficiency?

For example, I would add 7 lbs to my tun but the efficiency is only 0.85. Do I take 7*0.85 then multiply it by 0.65 if I want to get pounds of LME? I assumed the extracts are 100% efficiency.

Thanks!

potential gravity of ---
2-row: 1.036
LME: 1.038
DME: 1.042

36 * 0.70 mash efficiency = 25.2
25.2 / 38 = 0.66
25.2 / 42= 0.60

therefore if an all grain recipe assumes 70% efficiency, your ratio would be 0.66 pounds of liquid extract per pound of grain or 0.6 pounds of dry extract per pound of grain.

in a high-efficiency example, like your 85% example, the ratio would be
36* 0.85 = 30.6
30.6 / 38 = 0.81
30.6 / 42 = 0.73

therefore with 85% mash efficiency, your ratio would be 0.81 pounds of LME per pound of grain or 0.73 pounds of DME per pound of grain.

helpful chart - https://www.homebrewtalk.com/wiki/index.php/Malts_Chart

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the "short" answer is that the "typical" conversions you see assume an efficiency in the 68-75% range.

progmac said:

...redacted, recalculating

Click to expand...

haha, well my thought is that those conversion numbers must be somewhat accurate otherwise you'd hear peoples OGs and FGs turned out different than they expected.

I suspect it would be a per brewer calculation, as depending on your tun and method you will result in different efficiencies.

mezhan said:

haha, well my thought is that those conversion numbers must be somewhat accurate otherwise you'd hear peoples OGs and FGs turned out different than they expected.

I suspect it would be a per brewer calculation, as depending on your tun and method you will result in different efficiencies.

Click to expand...

i edited my original reply, should be more helpful

progmac said:

i edited my original reply, should be more helpful

Click to expand...

Awesome response, much appreciated! A lot more information than I expected, which is always a good thing!

Hopefully not too much of a side-track, but looks like about 10% difference between LME and DME. I thought it was more like 20% difference based on previous readings?

whoaru99 said:

Hopefully not too much of a side-track, but looks like about 10% difference between LME and DME. I thought it was more like 20% difference based on previous readings?

Click to expand...

I noticed that too. I used a potential gravity of 1.042 for DME, but I think in reality some of it is more like 1.045.

assuming 1.045 instead of 1.042 would make it look like:
2-row: 1.036
LME: 1.038
DME: 1.045

again using the examples of a 70% grain mash efficiency and an 85% grain mash efficiency --

36 * 0.70 mash efficiency = 25.2
25.2 / 38 = 0.66 pounds of lme per pound of grain
25.2 / 4= 0.56 pounds of dme per pound of grain

36 * 0.85 mash efficiency = 30.6
36* 0.85 = 30.6
30.6 / 38 = 0.81 pounds of lme per pound of grain
30.6 / 45 = 0.68 pounds of dme per pound of grain