Or is there an easier way? I have beersmith set at 75% efficiency, and I always come close to the estimated OG. (1.065 on BS, and I'll hit 1.060) I suppose I could adjust the efficiency in BS to the point where I'm right on, and figure that is my efficiency.
How do you all measure your efficiency?
I have been doing a lot of efficiency measuring recently just trying to get into the ballpark. After listening to the advice of others, I'm never going to worry about the difference between 72% and 75%, but I was having really low and inconsistent efficiencies. To try and pinpoint what is/was going on in my system and get consistent, I've been measuring all of the components off of Kai's spreadsheet that he linked.
The biggest things I have either measured or started recording that have helped have been the dead space in my MT (very easy to measure, add water to cover the outlet, drain, measure remaining water using something calibrated), which in turn has allowed for measuring my mash volume. This can also be done just by measuring the volume in your boil kettle after collecting (but then you are missing some information about grain absorption). Measuring the run-off gravities (at the correct temp) and the volumes in the MT, kettle, and fermenter have all helped me greatly.
I measure volume in my kettle using a meterstick, multiplying by the surface area of my cylindrical pot, and converting milliliters to gallons. My fermenter is marked and I just trust it enough for my rough calculations. I calibrated the 1/2 gallon pitcher I use on brew day using a pyrex measuring cup, which so far is working fine for my calculations. Again, not worrying about the 3% difference that will take my beer up or down a couple of points, I'm worried about the 10-20 point variations. All in all, the measurements I take on brew day now add an extra 10 minutes or so, but the information I get from calculating the efficiency has already helped my consistency greatly. Totally worth it to measure the variables, even if you don't need to calculate the values later on. If you end up with the right volume of the right gravity, then your efficiency was pretty damn good. But if not, it's going to be really hard to go back and collect the data you need once the beer is in the fermenter.