Portafilter Sizes Explained: What Size Is Your Espresso Machine?

One of the most common questions from home baristas is a simple one: what size portafilter does my machine take? It matters because everything that connects to your grouphead — replacement portafilters, baskets, tampers, and dosing rings — needs to match your machine's size exactly.

There are three standard sizes used across home espresso machines: 51mm, 54mm, and 58mm. Here's how to know which one you have, and which machines use which size.

The Three Standard Portafilter Sizes

51mm — De'Longhi, Smeg, and compact machines

51mm is the smallest of the three standard sizes and is most commonly found on De'Longhi's range of manual espresso machines. If you own a De'Longhi Dedica (any model), a De'Longhi La Specialista, or a Smeg ECF01, you're working with a 51mm grouphead.

The Dedica's slim 15cm-wide body is made possible in part by this smaller grouphead diameter — it's a deliberate design choice for compact machines. Despite the smaller size, 51mm machines are fully capable of producing excellent espresso when paired with a quality non-pressurised basket and proper technique.

Machines that use 51mm:

• De'Longhi Dedica EC680, EC685, EC695, EC785, EC885, EC950
• De'Longhi La Specialista EC9335, EC9155, EC9355, EC9665, EC9865
• De'Longhi Icona ECO310, ECO311, ECOV311
• Smeg ECF01

54mm — Breville mid-range machines

54mm is Breville's proprietary size used across their mid-range lineup. It's larger than the Dedica's 51mm but smaller than the industry-standard 58mm. If you own a Breville Bambino, Barista Express, Barista Pro, or Barista Touch, you're on 54mm.

One thing worth knowing: 54mm is essentially unique to Breville (and their Sage equivalents in the UK and Europe). Aftermarket accessory options are narrower than for 58mm, though the range has grown significantly in recent years.

Machines that use 54mm:

• Breville / Sage Bambino (BES450)
• Breville / Sage Bambino Plus (BES500)
• Breville / Sage Barista Express (BES870)
• Breville / Sage Barista Express Impress (BES876)
• Breville / Sage Barista Pro (BES878)
• Breville / Sage Barista Touch (BES880)
• Breville / Sage Barista Touch Impress (BES881)

58mm — The industry standard

58mm is the professional standard and is used across the widest range of home and commercial machines. If you own a Breville Oracle or Dual Boiler, a Gaggia Classic, a La Marzocco, or most E61-style machines, you're on 58mm. The aftermarket accessory ecosystem for 58mm is enormous — more basket options, tamper options, and upgrade parts than any other size.

Machines that use 58mm:

• Breville / Sage Dual Boiler (BES920)
• Breville / Sage Oracle (BES980)
• Breville / Sage Oracle Touch (BES990)
• Breville / Sage Oracle Dual Boiler (BES995)
• Gaggia Classic, Classic Pro, Classic Evo
• La Marzocco Linea Mini, GS3
• Rocket Appartamento, Mozzafiato
• ECM Classika, Synchronika
• Rancilio Silvia
• Most E61 grouphead machines

Why Does Portafilter Size Matter?

The portafilter size determines more than just which portafilter you can use — it determines the diameter of your filter basket, which affects your dose and puck depth, and the size of your tamper. A 51mm machine needs a 51mm tamper; a 58mm machine needs a 58mm tamper. Using the wrong size means your tamp won't seal properly and you'll get channelling and inconsistent extraction.

It also affects which upgrade parts are available. 58mm has the deepest ecosystem of aftermarket baskets, shower screens, and precision components. 54mm has grown considerably. 51mm has fewer options but the essentials — non-pressurised baskets, precision tampers, puck screens, and dosing rings — are all available.

The De'Longhi Dedica Portafilter: A Note on the Stock Version

If you've searched "De'Longhi Dedica portafilter size" you've probably already found that the answer is 51mm — but there's more to know than just the diameter. The stock Dedica portafilter comes with pressurised (double-wall) filter baskets. These are designed to produce crema-looking results with pre-ground coffee, but they mask extraction problems and limit how good your espresso can actually taste.

Upgrading to a non-pressurised basket (also called a single-wall basket) is the single most impactful upgrade you can make on a Dedica. Combined with freshly ground coffee and a proper 51mm tamper, it transforms the machine. Our De'Longhi Dedica Upgrade Guide covers exactly which upgrades to make and in what order.

Not Sure Which Size You Need?

If you're still not certain which portafilter your machine takes, use our Find Your Portafilter tool — select your machine from the list and it'll tell you exactly which size and style you need, with direct links to compatible options.

Once you know your size, browse our full range:

• 51mm Portafilters — De'Longhi Dedica, La Specialista, Smeg
• 54mm Portafilters — Breville Bambino, Barista Express, Barista Pro
• 58mm Portafilters — Breville Oracle, Gaggia, La Marzocco, E61