The number of bottles that come from a cask at bottling depend on the following factors:
- The size of the original cask
- How much spirit soaks into the wood on filling (typically about 5%)
- How much spirit has evaporated over time ("The Angel's Share"... usually 1-3% per annum)
- The size of bottle you put the whisky into (most commonly 70cl)
As an example:
- a newly filled 200L cask, aged for 5 years prior to bottling, would approximately yield:
200L x 5% = 10L on 'in fill'
190L x 2% in Year 1 = 3.8L
186.2L x 2% in Year 2 = 3.7L
182.5L x 2% in Year 3 = 3.7L
178.8L x 2% in Year 4 = 3.6L
175.2L x 2% in Year 5 = 3.5L
Approx. spirit remaining after 5 years = 172L
Which is approximately 245 x 70cl bottles.
This calculation excludes any small samples taken for tasting purposes or quality control (say, 100ml per year)
Additional examples:
- a newly filled 225L cask, aged for 5 years prior to bottling, would approximately yield:
225L x 5% = 11.25L on 'in fill'
214L x 2% in Year 1 = 4.3L
210L x 2% in Year 2 = 4.2L
206L x 2% in Year 3 = 4.1L
202L x 2% in Year 4 = 4.0L
198L x 2% in Year 5 = 4.0L
Approx. spirit remaining after 5 years = 194L
Which is approximately 275 x 70cl bottles.
- a newly filled 250L cask, aged for 5 years prior to bottling, would approximately yield:
250L x 5% = 13L on 'in fill'
237L x 2% in Year 1 = 4.7L
232L x 2% in Year 2 = 4.6L
227L x 2% in Year 3 = 4.5L
223L x 2% in Year 4 = 4.5L
219L x 2% in Year 5 = 4.4L
Approx. spirit remaining after 5 years = 215L
Which is approximately 310 x 70cl bottles.