How many standard drinks are in a cask of wine?
A cask of wine feels like the easy-going, nothing-to-see-here option — no bottles stacking up, just a quiet tap on the fridge. But a single 4-litre cask holds about 36 to 43 Australian standard drinks, roughly a month's worth of the weekly guideline. Here's the simple formula, a table by cask size, and why the "goon bag" is the easiest drink of all to lose count of.
The short answer
A standard 4-litre cask of wine contains somewhere between 36 and 43 standard drinks, depending on whether it's white or red and how strong it is. The national standard drinks guide lists a 4-litre cask of white wine (11.5% ABV) at about 36 standard drinks and a 4-litre cask of red (13.5%) at about 43. A smaller 2-litre cask — the classic "goon sack" — holds around 18 to 21.
Cask wine isn't weaker than bottled wine; it sits in the same 10–13.5% alcohol range. What makes a cask different is sheer volume and the fact that you can't see it going down. Four litres is more than five standard bottles of wine, all behind an opaque bag with a tap.
What counts as one standard drink?
An Australian standard drink contains 10 grams of pure alcohol — about 12.5ml of pure alcohol — no matter what it's poured into. The Alcohol and Drug Foundation defines it as that fixed unit, and it's the number Australian guidelines are built around. One standard drink is roughly 100ml of average wine, so a normal glass is already more than a single standard drink.
The formula (the same one for every drink)
You can work out the standard drinks in any container of wine — a glass, a bottle or a whole cask — with one line of maths:
For a 4-litre cask of red at 13.5% ABV: 4 × 13.5 × 0.789 = 42.6 standard drinks.
The 0.789 is the specific gravity of ethanol — the weight of one litre of pure alcohol in kilograms. It turns the volume of alcohol into its weight, so the answer lines up with the 10-grams-per-standard-drink rule. You only need the two numbers printed on the box: how many litres, and how strong.
Standard drinks by cask size
Cask wines range from roughly 10% for some budget whites up to about 13.5% for reds. Here's how the common sizes work out, using the figures from the national standard drinks guide:
| Cask | Typical ABV | Standard drinks |
|---|---|---|
| 2 litre white ("goon sack") | ~11.5% | ~18 |
| 2 litre red | ~13.5% | ~21 |
| 4 litre white | ~11.5% | ~36 |
| 4 litre red | ~13.5% | ~43 |
| 5 litre cask | ~11.5% | ~45 |
Even a budget 4-litre white at a lower 10% still works out to about 32 standard drinks (4 × 10 × 0.789). Whichever way you cut it, one cask is many weeks of drinking under the guidelines — not a single night's supply.
Why the goon bag is so easy to underestimate
With beer you can line up the empties, and with a bottle of wine you can see the level drop. A cask removes both of those cues at once. You pour from a tap into whatever glass is handy, the bag quietly collapses as it empties, and there's never a bottle on the bench to remind you how much is gone. It's the single hardest drink to keep an honest count of.
A few things stack the odds:
- No empties to count. One opaque bag replaces five-plus bottles, so there's no visible tally building up through the week.
- Top-ups, not glasses. A splash here and a splash there never registers as "another drink", but a 150ml home pour of average wine is about 1.4 standard drinks, and a generous 200ml pour is closer to 1.9.
- It keeps for weeks. The sealed bladder means a cask doesn't "go off" the way an open bottle does, so a glass or two most nights feels casual — but a cask that lasts a fortnight can still sail past 10 standard drinks a week.
- Cheap and plentiful. Cask wine is among the cheapest alcohol by the standard drink, which is exactly why it's easy to keep pouring.
How a cask compares to the guidelines
The National Health and Medical Research Council (NHMRC) advises healthy adults to drink no more than 10 standard drinks a week and no more than 4 on any one day, to reduce the risk of harm from alcohol. Set a cask against that and the scale becomes clear:
- A 4-litre cask (~36–43 standard drinks) is around four weeks of the entire weekly limit of 10.
- Even the smaller 2-litre goon sack (~18–21) is close to two weeks' worth in one bag.
- Finish a 4-litre cask across a single week and that's roughly four times the weekly guideline.
The healthdirect advice is to keep track of how much you're actually drinking, space drinks out and have alcohol-free days — all of which get harder the moment the counting is hidden inside a bag.
Keeping count when there's nothing to count
The maths on a cask is easy; the tracking is the hard part, because the one thing a cask never gives you is an empty to look at. The simplest fix is to log each glass as you pour it rather than trying to reconstruct the week from a half-empty bag.
That's exactly what the Drink Buddy app is built for. Tap in each glass from the cask and it keeps a running tally of your standard drinks, estimates your blood alcohol concentration in real time, and runs a live sobriety timer counting down to zero — so a "bottomless" box never quietly becomes more than you intended. If you're trying to bring your weekly number down, our guide to cutting down on drinking pairs well with it.
Frequently asked questions
How many standard drinks are in a 4 litre cask of wine?
Roughly 36 to 43. The standard drinks guide puts a 4-litre white (11.5%) at about 36 and a 4-litre red (13.5%) at about 43. The formula is 4 × ABV × 0.789.
How many standard drinks are in a 2 litre cask or goon sack?
About 18 to 21 — around 18 for a 2-litre white and 21 for a 2-litre red. That's still close to two weeks of the weekly guideline of 10 standard drinks.
Is cask wine weaker than bottled wine?
No. Cask wine is the same 10–13.5% strength as bottled wine. The difference is the volume and the fact that you pour from a tap with no empties to count, which makes it far easier to underestimate.
How many glasses are in a 4 litre cask?
About 26 to 27 glasses at a 150ml pour. Because each of those glasses is around 1.4 standard drinks, the whole cask adds up to roughly 36 to 43 standard drinks.
Does a cask lasting for weeks make it safer to drink?
No. The bladder keeps the wine fresh, but the alcohol inside doesn't shrink. A glass or two most nights from a long-lasting cask can still put you well over 10 standard drinks a week without it ever feeling like a big session.
Sources
Written by the Trendy Publishing editorial team from the sources below. This is general information only, not medical or legal advice — check with your doctor, pharmacist or the relevant authority for your situation.
- Australian Government Department of Health — standard drinks guide
- Alcohol and Drug Foundation — What is a standard drink
- NHMRC — Alcohol
- healthdirect Australia — Tips for safe drinking