Demijohn vs Carboy: What's the Difference, and Which Do You Need?

If you've spent any time browsing home brewing forums, you've probably seen "demijohn" and "carboy" used interchangeably — and then wondered if you're missing something. Here's a straight answer, plus how to pick the right one for your setup.

Demijohn vs Carboy: Are They the Same Thing?

Largely, yes. In the UK, "demijohn" is by far the more common term — typically referring to a narrow-necked glass or PET vessel, usually 1 gallon (4.5 litres) in size, used for fermenting and storing wine, cider or beer. "Carboy" is the term more commonly used in the US and Canada, and can sometimes refer to slightly larger vessels (5 gallons/23 litres is a common carboy size). If someone in the UK says carboy, they almost always mean the same thing as a demijohn.

Glass or PET (Plastic)?

Both have their place:

• Glass demijohns don't scratch, don't retain odours or stains, and are the traditional choice — but they're heavier and can (rarely) crack or shatter if mishandled.
• PET plastic demijohns are lighter, shatterproof, and much safer to handle when full — ideal if you're moving demijohns around often, or just want the extra peace of mind. They can scratch over time, so a bit more care is needed when cleaning.

For most home brewers, either works well — it really comes down to personal preference and how you'll be using it.

What Size Do You Need?

The standard UK size is 1 gallon (4.5 litres), which matches most wine and cider kit recipes and is a manageable size to lift and handle when full. Some brewers use smaller sizes for trial batches or bigger vessels (demijohns are also available up to around 30 litres) for larger batches, but 4.5 litres is the go-to starting point for most home wine, cider, and secondary beer fermentation.

What Else Do You Need With It?

A demijohn on its own isn't quite ready to use — you'll also want:

• A bung (cork or rubber) sized to fit the neck.
• An airlock, fitted through the bung, to let CO2 escape without letting air (and contaminants) in.
• A means of sanitising it thoroughly before each use.

Shop Demijohns at Brewco

We stock both glass and PET demijohns, along with all the bungs, airlocks and cleaning supplies you'll need. Browse our home brewing equipment range, or head straight to our wine and cider making kits if you're just getting started.