A Craft Beer & Brewing Magazine reader recently asked us the following question:
I live in Colorado and brew at high altitude. Is it true that altitude can affect my hopping rate?
As altitude increases, the boiling point of water decreases. The practical effect of this is that your boil-hops additions boil at a lower temperature, which results in lower hops utilization. So at altitude, you may actually need more hops to achieve a given bitterness than a brewer at sea level.
So how much reduction in hops utilization do you get at altitude? My friend John Palmer recently wrote an article on the subject (“A look at Isomerization Reduction due to Altitude,” MBAA, Vol. 54, No. 3, 2017). He covers the subject in some detail, but I summarize his findings here.