Oatmeal stout 1.020 FG - Calculator wrong?

[Rush]

Recipe will follow.

According to Brewers Friend this recipe should have had a FG of 1.011. I brewed this beer Sunday, saw activity throughout the week. Checked gravity Thursday and Saturday morning and FG was 1.020 both times. I'm not planning on kegging this for 2 more weeks but I was just wondering if I should expect this to dry out any more and why the estimates from the calculator and my actual results are so different. Any thoughts?

This is my 5th all grain, so I'm still getting my bearings straight. Typically I have hit my numbers fairly close, within a couple of gravity points. Nearly 10 points from expected is quite off though.

Mash temp was 155 @ 60m

Oatmeal Stout - Simple
Method: BIAB
Style: Oatmeal Stout
Boil Time: 60 min
Batch Size: 5.5 gallons (fermentor volume)
Boil Size: 7.5 gallons
Boil Gravity: 1.038 (recipe based estimate)
Efficiency: 75% (brew house)

Original Gravity: 1.052 Final Gravity: 1.011 ABV (standard): 5.46% IBU (tinseth): 40.11 SRM (morey): 36.06
Fermentables
Amount Fermentable PPG °L Bill %
7 lb United Kingdom - Maris Otter Pale 38 3.75 65.1%
2 lb Flaked Oats 33 2.2 18.6%
1 lb American - Black Barley 27 530 9.3%
0.5 lb American - Carapils (Dextrine Malt) 33 1.8 4.7%
0.25 lb American - Caramel / Crystal 40L 34 40 2.3%
10.75 lb Total
Hops
Amount Variety Type AA Use Time IBU
0.7 oz Warrior Pellet 14.3 Boil 60 min 38.39
0.5 oz Willamette Pellet 4.5 Boil 5 min 1.72
Hops Summary
Amount Variety Type AA
0.7 oz Warrior Pellet 14.3
0.5 oz Willamette Pellet 4.5
Mash Guidelines
Amount Description Type Temp Time
-- Temperature 155 F 60 min
Yeast
Fermentis / Safale - American Ale Yeast US-05
Attenuation (avg):
81%
Flocculation:
Medium
Optimum Temp:
54 - 77 °F
Starter:
No

 

[Yooper]

I love using calculators for my brewing- but the FG estimation is almost impossible to calculate properly.

In theory, the calculator should take all the factors that go into the actual FG into account- ingredients, yeast strain attenuation, mash temperature, etc.

But the reality is that they usually don't come all that close. In looking at your recipe and the mash temp, I would predict 1.020 or so myself from those ingredients and most especially that mash temperature.

 

[Rush]

I love using calculators for my brewing- but the FG estimation is almost impossible to calculate properly.

In theory, the calculator should take all the factors that go into the actual FG into account- ingredients, yeast strain attenuation, mash temperature, etc.

But the reality is that they usually don't come all that close. In looking at your recipe and the mash temp, I would predict 1.020 or so myself from those ingredients and most especially that mash temperature.

Thanks for the response!

How much of a difference in FG do you feel I should expect dropping the mash temp to 150-152 range?