Hitting IBU Estimates in Published Recipes

[BluesNBrews]

I'm having trouble when I try to convert recipes from a magazine to my brewing software and hopefully someone can explain this. When I load a recipe from Zymurgy onto Beersmith for an IPA I'd like to make. The calculated IBUs are significantly less than the estimate they Published. I'm sure it's not a misprint but I don't understand why this happens. The AVB is right on the money. Thanks.

 

[LLBeanJ]

Rager vs Tinseth IBU calculation? I believe the default in BS is Tinseth, but (IIRC) a recipe that uses Rager will show more IBUs. This can be changed in the Options setting in BS.

 

[dmtaylor]

Most publications seem to prefer the Rager method to calculate IBUs, while most softwares tend to default to the Tinseth method. In reality, Tinseth is the most accurate of all methods, and tends to be the smaller number. In any case, when in doubt, the smaller number is most likely the most accurate, as all formulae tend to overdo it just a tad compared to actual laboratory results. If you really want to know for sure, you need to send samples of your beer to a lab, which can cost up to $100 for accurate results. But in a pinch, Tinseth will get you the closest. I'm pretty sure BeerSmith uses Tinseth by default. Make sure and then use it.

 

[botigol]

The boil volume or duration may be different. Also, the calculated density of your wort could affect the hop utilization. This would mostly be an issue with extract batches.

 

[BluesNBrews]

This is all really helpful, thank you very much!