Whisky · Explainer
Why does the same whisky taste different per batch?
Every batch is put together from different casks, and oak varies from tree to tree, from growing site to growing site and from lot to lot. On top of that, a cask loses about 2 percent of its contents per year and changes in strength. The difference is most noticeable in cask strength bottlings, because no water is added to even out the flavour.
In brief
The key figures
| Cause 1 | other casks in the composition |
|---|---|
| Cause 2 | variation in oak per tree and per batch |
| Cause 3 | evaporation, about 2 percent per year |
| Cause 4 | cask size determines the maturation rate |
| Maturation rate | 18 months in a hogshead is roughly equivalent to two years in a butt |
| Hogshead and butt | 250 litres versus 500 litres |
| Legal minimum | 40 percent alcohol at bottling |
| What the law does not regulate | consistent flavour between successive batches |
What is a batch in whisky?
A batch is one composition from a number of casks, bottled in one go and often numbered on the label.
At the next batch other casks are combined. Even if the distillery, cask type and age stay the same, the contents of those casks are never exactly the same.
A batch number is therefore not a version number of a recipe, but an indication of which casks were in this batch.
Why do casks of the same type differ from one another?
The properties of oak vary by tree, by growing site and by batch, both in fresh wood and in previously used casks.
Mosedale mapped that variation in 1995 in Forestry, a journal of forestry research, in an overview of the influence of oak wood on whisky. Chemical and anatomical properties of the wood vary, and those differences carry through into maturation.
Add to that the history of the cask: what it held before, how often it has been used and how heavily it has been charred.
How much influence does cask size have?
A smaller cask matures faster, because per litre of whisky more liquid comes into contact with the wood.
Whisky Magazine quotes a master blender who states that what takes eighteen months in a hogshead takes two years in a butt. A hogshead holds 250 litres, a butt 500 litres.
If a batch is composed from different cask sizes than the previous one, the flavour profile shifts with it.
Why does the difference stand out at cask strength?
When bottling at cask strength no water is added, so the alcohol content per batch moves with the casks.
A standard bottling is reduced to a fixed percentage, which dampens differences. At cask strength that step is missing, and flavour and strength differ from batch to batch.
Bottlers therefore often state a batch number or a cask number on the label for cask strength.
May a bottle taste different from batch to batch?
The rules set requirements for raw material, maturation and alcohol content, but do not prescribe that successive bottlings taste the same.
The Scotch Whisky Regulations 2009 require maturation of at least three years in oak casks of at most 700 litres and at least 40 percent alcohol at bottling. Regulation (EU) 2019/787 sets the European framework for spirit drinks.
Equal taste between batches is therefore a choice made by the producer and not a legal requirement.
How can you tell which batch you are holding?
A batch number, a bottling year or a cask number on the label tells from which composition the bottle comes.
If nothing is stated, the bottle usually belongs to a continuous standard bottling. With independent bottlers and with cask-strength bottlings, a number is more the rule than the exception.
Note that number if you want to find a bottle again later. Two bottles with the same label but a different batch number are not the same whisky.
From the shop in Bathmen
Which whiskies at high cask strength are there in Bathmen?
The shop in Bathmen stocks 159 whiskies of 60 percent alcohol and higher from 68 different brands from 10 countries. Prices range from € 17.49 to € 2,599.00. The alcohol percentage ranges from 60% to 73.7%.
- Aberlour A'Bunadh Alba 62.7% · 70 cl · Scotland
- Aberlour A'Bunadh Batch #75 60.9% · 70 cl · Scotland
- Aberlour A'Bunadh Cask Strength Batch #84 61.2% · 70 cl · Scotland
- Adelphi Ardmore 2016 2024 61.1% · 70 cl · Scotland
- ADELPHI GLENROTHES 10 Y Distilled 2009 65.5% · 70 cl · Scotland
- Adelphi Limited Ardbeg 14Y 2004 #700171 60.7% · 70 cl · Scotland
- Amrut Peated Indian Cask Strength 62.8% · 70 cl · India
- Amrut Single Malt Cask Strength India Whisky 61.8% · 70 cl · India
- Annadale Man O'Words 2015 60.8% · 70 cl · Scotland
- Annandale Man O'SWord 2015 60.8% · 70 cl · England
Related questions
Why is whisky bottled at 40 per cent?Why does whisky turn cloudy when you add ice or water?Why are whisky stills made of copper?
Short answer
Short answers to related questions
- Is a difference between batches a flaw?
- No. Differences between batches are part of cask-matured drinks and are often stated on the label for cask strength.
- What is a single cask?
- A bottling from one cask. No second batch with the same contents follows.
- Why is a standard bottling more stable?
- Many casks are blended together and brought down to a fixed alcohol content, so differences stand out less.
- Is there always a batch number on the bottle?
- No. It occurs mainly with cask strength bottlings and small series.
The reasoning
Sources
- Effects of oak wood on the maturation of alcoholic beverages with particular reference to whisky, Forestry: An International Journal of Forest Research, Mosedale 1995 (accessed 7 September 2026)
- Sizing Up Casks, Whisky Magazine (accessed 2026-09-07)
- Personal Investment in a Scotch Whisky Cask, Scotch Whisky Association (accessed 2026-09-07)
- The Scotch Whisky Regulations 2009, regulation 3, legislation.gov.uk (accessed 2026-09-07)
- Verordening (EU) 2019/787 over gedistilleerde dranken, EUR-Lex, European Union (accessed 2026-09-07)
This page was written and checked by ’t Bockje Bathmen, wine & spirits shop at Brink 2 in Bathmen. Last updated on 8 September 2026.
Verkoop van alcohol onder de 18 jaar is verboden. NIX18.