Why Tamper Size Matters
A coffee tamper compresses the ground coffee in your portafilter basket to create an even, consistent surface for water to pass through.
If your tamper is too small, water will find weak spots along the edge (known as channeling), leading to sour or weak shots. If it’s too big, it won’t fit properly, making it awkward or impossible to tamp evenly.
The goal: match your tamper size to your basket’s internal diameter as closely as possible—usually within 0.1–0.3 mm of the basket size.
Common Sizes: 54 mm vs 58.5 mm
Most modern espresso machines fall into one of these two camps:
| Size | Fits Basket Diameter | Common Machine Examples | Notes |
|---|---|---|---|
| 54 mm | ~54–54.5 mm | Breville/Sage Barista Express, Barista Pro, Barista Touch, Bambino | Slightly smaller baskets, often in consumer-grade machines |
| 58.5 mm | ~58–58.7 mm | Gaggia Classic, Rancilio Silvia, most E61 group machines (Lelit, Rocket, ECM), prosumer & commercial | “Precision” size for 58 mm baskets—fills edge-to-edge, reduces channeling |
Tip: 58.0 mm tampers exist, but 58.5 mm is preferred by many pros because it fits tighter to the basket wall, leaving minimal untamped coffee.
How to Measure Your Basket
- Remove the basket from your portafilter.
- Measure the inside diameter across the top rim (not the outside).
- Round down to the nearest 0.1 mm.
- Choose a tamper that’s 0.1–0.3 mm smaller than this number.
Example:
- Basket inner diameter: 54.3 mm → choose 54 mm tamper.
- Basket inner diameter: 58.6 mm → choose 58.5 mm tamper.
Precision Tampers vs Standard
- Standard tampers leave a small gap (~0.5–1 mm) to prevent sticking—fine for casual use.
- Precision tampers (like 58.5 mm for a 58.6 mm basket) give more even compression, reducing channeling.
These work best if you dose coffee consistently and keep the basket clean at the rim.
Which Should You Choose?
- If you own a Breville/Sage consumer model → go 54 mm.
- If you own a Gaggia, Rancilio, or prosumer E61 group machine → go 58.5 mm.
- Unsure? Search your model online + “basket size” or check your manufacturer’s specs.
Pro Tips for Better Tamping
- Consistent pressure (~30 lbs) is less important than level tamping—avoid a tilted puck.
- Use a dosing funnel to keep grounds from spilling and maintain a neat edge.
- Pair your tamper with a puck screen to improve extraction consistency.
Ready to Upgrade Your Workflow?
We stock precision 54 mm and 58.5 mm tampers designed to fit your exact machine—plus dosing funnels, WDT tools, and puck screens to take your espresso game to the next level.