Dry hop rates, converted without the barrel mix-up

How many grams per litre is 1 lb/bbl?

3.87 g/L for a US barrel and 2.77 g/L for a UK barrel. The 40 percent gap is the most common dry hop conversion mistake.

Does adding more dry hops add more aroma?

Only up to a point. Tom Shellhammer’s group at Oregon State took a lightly hopped pale ale, 4.75 percent ABV and 19 IBU, and dry hopped it with whole cone Cascade for 24 hours at rates from 2 to 16 g/L, then measured the beers analytically and with a trained panel. Above about 8 g/L, extraction of hop oils and the aroma they carry were close to saturated: more hops in the same addition returned very little. The oils behind citrus aromas saturated earlier, near 4 g/L, while herbal and tea notes and the bitter, astringent compounds from hop matter kept climbing. So a heavier single charge does not simply make the beer more aromatic; it shifts the aroma toward herbal and adds bitterness. That is why large totals are split across two or three additions rather than added at once. Single static addition, Cascade, one base beer: other hops and processes may move the numbers.

Reported by Brülosophy from Shellhammer’s presentation; the underlying paper is LaFontaine and Shellhammer.

Is a US barrel the same as a UK barrel?

No. A US barrel is 31 US gallons, 117.35 litres. A UK barrel is 36 imperial gallons, 163.66 litres. The same rate in lb/bbl is 40 percent stronger in a US barrel.