CHEMEX Sizes, Filter Types & Folding Guide for Pour-Over Coffee

If you love the clean, bright cup of a well-brewed pour-over but struggle to choose the right CHEMEX model—or figure out which filter goes with it—you’re not alone. The CHEMEX’s iconic hourglass design combines brewer and server, but its various sizes require specific filters and correct folding techniques. Whether you're using a 1-cup single serve or brewing for a group with a 13-cup model, getting the right filter and fold makes all the difference.

Here’s the quick answer: CHEMEX comes in sizes from 1–3 cups (with semi-circle filters), 6–10 cups (with either square or round filters), and up to 13 cups (also with semi-circle filters). Each size uses a specific filter type, and all filters require a precise fold—either half-moon, square, or circular—to brew properly.

CHEMEX Sizes: From Solo Cups to Group Brewing

CHEMEX coffee makers are instantly recognizable for their sleek glass design where the filter cone and decanter are fused into one piece. They’re available in multiple sizes to suit different brewing needs:

• 1–3 cup models: Ideal for single servings or small households. These come with either a wooden handle and leather tie, or a glass handle.
• 6, 8, and 10 cup models: Great for making multiple cups at once, suitable for sharing or larger mugs. Also offered with wood + leather or glass handles.
• 13 cup model: Designed for bigger batches, perfect for serving several people. Comes with either a wood + leather handle or glass handle.

Each CHEMEX size is engineered for optimal flow rate and extraction, which is why using the correct filter—and folding it properly—is essential.

Filter Paper Types by CHEMEX Size

Different CHEMEX sizes use different filter paper shapes. Using the wrong shape can cause over- or under-extraction, affect brew time, or even lead to grounds in your cup. Here’s how they break down:

• 1–3 cup CHEMEX: Uses a semi-circle filter. This is the most common filter shape and fits the smaller models perfectly.
• 6, 8, and 10 cup CHEMEX: Can use either square filters or round filters. Both are designed to match the larger brew area and flow dynamics of these mid-sized models.
• 13 cup CHEMEX: Uses a semi-circle filter, just like the smallest models.

The variation in filter shapes ensures proper saturation, even flow, and the signature clean cup CHEMEX is known for.

How to Fold CHEMEX Filters Correctly

Every CHEMEX filter—whether semi-circle, square, or round—requires a specific fold before brewing. Folding the filter correctly ensures even water flow, proper pre-wetting, and prevents bypass. Here’s how each type is folded:

Semi-circle Filters (1–3 cup and 13 cup CHEMEX)

The classic semi-circle filter is used in the 1–3 cup models and the 13 cup model. To fold:

• Fold the filter in half, forming a semi-circle along the printed seam.
• Place the folded filter into the CHEMEX with the triple-folded side facing the spout. This directs brew water away from the pouring channel and into your coffee bed.

Square Filters (6, 8, 10 cup CHEMEX)

Some medium-capacity CHEMEX models use square-shaped filters. To prepare:

• Fold the square filter diagonally or as indicated by printed guides (if any).
• Place the filter into the CHEMEX with the folded edge facing the spout, aligning it to direct flow away from the pour channel.

Round Filters (6, 8, 10 cup CHEMEX)

Other medium models use round filters. Folding is minimal but placement is key:

• No complex fold is required—round filters are pre-shaped.
• Insert with the domed side up or as oriented for best flow toward the carafe, ensuring the spout remains unobstructed.

Why Filter Choice and Folding Matter

Using the correct CHEMEX filter isn’t just about fit—it directly influences your coffee’s extraction. The wrong filter can:

• Slow down or speed up brew time unnaturally
• Cause uneven saturation of coffee grounds
• Allow coffee dust or fine particles into your cup
• Affect clarity and body in the final cup

The fold ensures the filter sits properly in the cone, directs water through the coffee bed efficiently, and preps the filter to adhere to the glass during brewing. It’s a small step that makes a big difference in clarity and flavor.

Frequently Asked Questions

What size CHEMEX should I buy?

Choose based on how much coffee you usually brew: 1–3 cups for solo or small use, 6–10 cups for sharing or larger mugs, and 13 cups for making coffee for several people. All sizes maintain CHEMEX’s signature clean extraction.

What’s the difference between semi-circle, square, and round filters?

Semi-circle filters fit 1–3 cup and 13 cup CHEMEX models. Square and round filters are for 6, 8, and 10 cup models. Each shape is designed to match the brewer’s flow dynamics and ensure proper extraction and clarity.

Do I really need to fold the filter a certain way?

Yes. Folding the filter correctly ensures even saturation, proper flow, and prevents coffee grounds from entering your cup. The triple-folded side of semi-circle filters should always face the spout.

Can I use any filter in my CHEMEX?

No. Always match the filter type to your CHEMEX size. Using the wrong shape can lead to poor extraction, slower flow, or grounds in your coffee.

Where can I find the correct CHEMEX filters?

Buy official CHEMEX filters directly from the CHEMEX website or trusted specialty retailers. Ensure the filter shape matches your CHEMEX model—semi-circle, square, or round.

Recommended FrontStreet Beans for Chemex Brewing

For Chemex pour-over, we recommend FrontStreet Coffee’s Ethiopia Humbera for its vibrant citrus and floral notes, and PWN Golden Mandheling for a balanced profile with sweet caramel and mild spice. Both shine in the Chemex’s clean-filtered brew. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.