Converting beersmith calculations (IBU, SRM) with different batch size (5 to 4)

[jdahl10]

I made an ESB on Sunday, and I ended up with a 4 gallon batch instead of 5.

Ended up boiling for 10 extra minutes by accident (I think it will end up more like a lighter Black IPA).

Anyway I ended up with 4 gallons instead of 5, which I'm sure was not all boiled off in those 10 minutes, and I have since realized that I should have just topped it off to 5.

The target OG was 1.056, but I measured 1.070, I'm guessing because the volume was less.

How do I estimate the IBU and SRM now with the new volume? Beersmith calculated IBU to be 68.1 (It doubled with that extra 10 min of boiling) and SRM 16.8.

Thanks!

Julian

 

[GPP33]

Just adjust the batch size to be the actual achieved. Everything else will update.

 

[bobeer]

If I'm understanding you correctly if you're asking what the IBU's are now that it's a 4 gallon batch instead of a 5 then just adjust the batch size from 5 to 4 like GPP33 said above.
You could also adjust the boil time too to 70 minutes and see what affect that has on the final numbers in a 5 gallon batch. If you have your equipment profile setup to reflect what you're actually using it may give you a more accurate depiction on what the numbers are. It should also take the extra volume off as well. Maybe do both, compare, and go with whichever you feel to be more accurate.

 

[GPP33]

I wouldn't stress too much about either number as they are very rough guesses. Actual numbers will vary quite a bit between ingredient suppliers and brew systems.

 

[Oginme]

I wouldn't stress too much about either number as they are very rough guesses. Actual numbers will vary quite a bit between ingredient suppliers and brew systems.

^^^This^^^

IBU calculations are usually OK within 5 or so IBU anyway. The best way to determine what you have for bitterness is through either a lab analysis ($) or through your taste buds. A good idea of how accurate the IBU models are can be found in a recent Experimental Brewing podcast, where they had several of their Igors brew the same recipe and then had the IBU tested through a lab in Oregon (I think). The wide variance in numbers is staggering.

link: https://www.experimentalbrew.com/podcast/episode-33-bitter-truth

 

[jdahl10]

I couldn't a 4 gallon option. It only lets me choose between 5, 1, 3.5, and 10. Maybe because I'm using the mobile app?

 

[GPP33]

Never used the mobile app. That would be pretty stupid though. The PC app lets you put in whatever you want.

 

[Oginme]

I couldn't a 4 gallon option. It only lets me choose between 5, 1, 3.5, and 10. Maybe because I'm using the mobile app?

I don't' use the mobile app either, but you should be able to customize an equipment profile to match your intended batch size and process conditions.