Dosing 101: 18g vs 20g Baskets – Which One to Use?

Upgraded my filter basket and immediately got confused by all the sizing options. 18g, 20g, 22g—what do these numbers actually mean, and does it matter for my Barista Express?

Turns out it matters quite a bit. The wrong basket size leads to headspace problems that mess up extraction. Here’s what I’ve learned comparing different baskets.

Understanding Espresso Basket Sizing

What Do the Numbers Mean?

An “18g basket” is designed to hold 18 grams of ground coffee optimally. Doesn’t mean you can’t use 17g or 19g—but 18g gives you the ideal headspace between coffee puck and shower screen.

The ±1g Rule

Golden rule: Dose within ±1g of your basket’s rated capacity.

Basket Size	Optimal Dose Range
18g	17-19g
20g	19-21g
22g	21-23g

Going outside this range causes problems: too little coffee creates excessive headspace (poor extraction), too much leaves no headspace (puck smashes against shower screen).

18g vs 20g: Key Differences

Extraction Characteristics

Factor	18g Basket	20g Basket
Hole count	Fewer holes	More holes
Flow resistance	Higher	Lower (more even)
Grind required	Finer	Slightly coarser
Forgiveness	Less forgiving	More forgiving
Typical output	~36g	~40g

Flavor Profiles

18g Basket: Often produces more concentrated shots with pronounced acidity and clarity. Higher resistance creates more pressure against the puck.

20g Basket: Tends toward fuller body and sweetness. Additional holes allow more even flow distribution, which reduces channeling.

When to Choose Each Basket

Choose 18g When:

1. You prefer smaller, concentrated shots
2. Your grinder produces fine, consistent particles (reduces channeling risk)
3. You drink straight espresso (not milk drinks)
4. You use light roasts that benefit from higher extraction
5. You want classic ristretto-style shots

Choose 20g When:

1. You prefer larger shots (40g+ output)
2. You make primarily milk drinks (bigger dose punches through milk)
3. You use dark roasts that extract easily
4. You want more forgiving extraction (better for learning)
5. You’re upgrading from stock Breville baskets

Basket Types: VST vs IMS vs Stock

Stock Breville Baskets

The included baskets are functional but imprecise. Hole sizes vary, leading to uneven extraction. Fine for learning, but worth upgrading eventually.

VST Precision Baskets

Pros:

• Laser-cut holes for exact sizing
• Extremely consistent extraction
• Industry standard for professionals

Cons:

• Less forgiving of grind inconsistencies
• Require good distribution technique
• Premium price ($35-50)

IMS Precision Baskets

Pros:

• Similar precision to VST
• Often slightly more forgiving
• Good range of sizes

Cons:

• Can be harder to find
• Similar price to VST

I switched to an IMS 18g basket about six months in and immediately noticed more consistent shots.

Headspace: Why It Matters

Headspace is the gap between tamped coffee puck and shower screen. It affects:

1. Water distribution: Proper space lets water spread evenly before hitting puck
2. Extraction evenness: No headspace = puck touches screen = channeling
3. Cleaning: Stuck pucks are a nightmare to knock out

Checking Your Headspace

After tamping, insert portafilter without locking in. Remove it and check:

• Good: Slight impression from screen, even marks

• Too little: Deep grooves, coffee sticking to screen
• Too much: No marks at all, puck may be too loose

The razor tool that came with your Breville helps achieve consistent headspace by trimming excess grounds.

Practical Recommendations

For Breville Barista Express Owners

Start with: The included 2-cup single wall basket (rated for ~18g)

Recommended upgrade: 18g VST or IMS basket

Why not 20g? The Breville’s 54mm portafilter limits basket depth. A 20g basket may have inadequate headspace in some shots.

For Different Drinks

Drink	Recommended Basket	Dose	Yield
Espresso	18g	18g	36g
Americano	18g	18g	36g
Latte	18g or 20g	18-20g	36-40g
Cappuccino	18g	18g	36g

Common Dosing Mistakes

Under-Dosing

Signs: Fast extraction, sour taste, watery texture

Fix: Increase dose or use smaller basket

Over-Dosing

Signs: Slow/choking extraction, bitter taste, puck touching screen

Fix: Decrease dose or use larger basket

Inconsistent Dosing

Signs: Variable shot quality day-to-day

Fix: Use a scale for every single dose. Essential for espresso.

Frequently Asked Questions

What’s the ideal dose for an 18g basket?

18g ±1g. Use 17-19g for optimal headspace and extraction.

Does basket size affect taste more than dose?

They work together. Properly dosed 18g basket produces different results than under-dosed 20g basket, even at same total weight.

Are 18g and 20g baskets universal across machines?

Not entirely. Basket diameter must match your portafilter (54mm for Breville, 58mm for most commercial). Depth matters too.

Should I buy multiple basket sizes?

Eventually, yes. Having 18g for straight espresso and 20g for milk drinks offers flexibility. But master one size first before collecting baskets.

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Related Guides:

• Tamping Technique: The 30lbs Myth
• Razor Tool Guide: Perfect Headspace
• Understanding Channeling