OG consistently too high

Hi,
I searched, but most issues dealt with extract batches. My OG is consistently too high, and am trying to figure out why. For example, yesterday's brew day is as follows.

Some background: I'm in Japan, so measurements are metric. I do two BIAB batches in a 28.2 liter (7.45 gallon) pot and combine in a carboy.

I followed EdWort's Rye IPA recipe, 5.5 gallon batch, OG of 1.064, which is:
10# 2-Row Pilsner
2# Rye
2# Vienna
12 oz. Crystal 60L
8 oz. Flaked Barley

I halved the recipe for each batch, so one batch was:
2,300g 2-Row Pilsner (5.07#)
500g Rye (1.10#)
500g Vienna (1.10#)
200g Crystal 60L (7.05 oz.)
200g Flaked Barley (7.05 oz.)
*The weights aren't exactly half of the original recipe since my LHBS sells grains by the 100g.

For the first batch, I ended up with ~8.5 liters (2.25 gallons) of wort, with a OG of 1.084 (20.1% Brix).

For the second batch, I started with 2 liters more water, and ended with ~10.5 liters (2.77 gallons) of wort, with an OG of 1.075 (18.0% Brix).

I am measuring gravity with a Hanna digital refractometer.

I believe EdWort calculates his efficiencies as 75%, and when I plug in my numbers here: http://www.brewersfriend.com/brewhouse-efficiency/, I get the following:

First batch: 63.18%
Second batch: 69.45%

Please help!

I'm not surprised. When I plug EdWort's recipe into BeerSmith, I have to reduce efficiency down to 64% in order to get a 5.5 gal batch to come in at 1.064. At 75%, it's more like 1.072. My efficiency for BIAB is routinely in the low-80% area, which for this recipe would get you up to 1.077-1.079 OG.

I'd say you're hitting about 81% efficiency, which is perfectly normal for BIAB and with this particular grain bill, that should yield an OG in the neighborhood of 1.078.

So, if you want to lower your OG, use less grain. To come in around 1.064, you should have a total of about 12.5 lbs (give or take) instead of the ~15 you're using now.

Thanks LLBeanJ! I'll look into that.

I also realized that I needed to measure the pre-boil volume and gravity to calculate efficiency!