Siphon Coffee Ratio and Grind Size: The Complete Guide

Every brew method on this site so far moves water through or over coffee by gravity, pressure, or a slow simmer. Siphon coffee, also called vacuum pot coffee, does something none of them do: it uses heat and air pressure to pull water upward into a chamber of grounds, then lets a vacuum pull the brewed coffee back down through a filter once the heat is removed. It looks like lab equipment because it essentially is lab equipment, two glass chambers, a filter, and a physics trick borrowed from a Bunsen burner. Search for a siphon coffee ratio and you will find real disagreement rather than the tidy single-number consensus this site found for Kalita Wave: one sourced guide states 16:1, another states 1:13. Here is why those numbers are not as far apart as they look, the grind both sources actually agree on, and the full two-chamber method.

How siphon brewing actually works

A siphon setup has two chambers stacked vertically: a lower bulb that holds water, and an upper chamber, connected by a tube with a cloth or metal filter at its base, that holds the coffee grounds. You apply heat, usually a butane burner or halogen stand, under the lower bulb. As the water heats, expanding vapor pressure forces it up the tube into the upper chamber, where it meets the grounds and brews for roughly a minute of full immersion. Pull the heat away and the vapor in the lower chamber cools and contracts, creating a vacuum that pulls the brewed coffee back down through the filter, leaving the spent grounds behind in the upper chamber. The whole process takes about three minutes and produces a cup that tastes closer to a clean pour-over than a French press, despite spending its brewing time as a full immersion method.

The ratio: 16:1 and 1:13, reconciled

Two independently written guides land on ratios that look like they disagree until you convert them to the same notation. Sprudge, covering the Hario TCA-5 siphon maker, specifies 35 grams of ground coffee to 560 milliliters of water, describing its own house standard directly: “Sprudge brew guides utilize a brew ratio of 16:1 by weight, that is, for every 16 grams of water used, 1 gram of coffee is used.” My Home Barista states a standard of 15 grams of coffee per 200 milliliters of water, which it writes as 1:13, along with a stronger option of 16 grams per 200 milliliters (1:12) and a lighter option of 13 grams per 200 milliliters (1:15).

Flip Sprudge’s ratio into the same coffee-first notation My Home Barista uses and the two numbers move much closer together. Sprudge’s 16:1 water-to-coffee is 1:16 coffee-to-water, meaning 1 gram of coffee per 16 grams of water, distinctly lighter than My Home Barista’s 1:13 standard. That is a genuine difference, not a notation trick, roughly the gap between a 1:12 immersion-strength French press and a 1:16 pour-over. The honest read: siphon coffee has real range depending on house style, from a stronger roughly 1:12 to 1:13 cup to a lighter roughly 1:15 to 1:16 cup, and both ends produce a legitimate, well-documented result rather than one source being wrong.

Ratio by cup size, in grams

If you are brewing on a Hario-style siphon sized for 3 to 5 cups, start at 1:13 as a reasonable middle default, then move toward 1:12 for a bolder cup or 1:16 if Sprudge’s lighter house style suits your taste better. Change only the coffee dose between test brews so you know exactly what shifted the result, the same approach this site’s coffee to water ratio chart recommends for dialing in any method.

The grind: medium to medium-fine, with one real disagreement

The two sourced guides describe the grind slightly differently, and it is worth naming the disagreement honestly rather than picking a side. Sprudge calls for a straightforward “medium” grind, comparing the texture to beach sand. My Home Barista is more specific, calling for “medium-fine,” describing it as “slightly finer than drip or pour-over, noticeably coarser than espresso,” and comparing the texture to fine table salt.

This site’s own grind size chart already places siphon in a 375 to 800 micron band, described there as “medium-fine, between a V60 and a Chemex grind,” which sits closer to My Home Barista’s description than Sprudge’s. Read the two sourced guides together and the honest range is medium to medium-fine, distinctly finer than a standard drip grind and distinctly coarser than espresso. If your cup tastes weak or thin despite hitting your target ratio, that is usually a sign to nudge finer within this band before assuming the ratio itself is wrong; if it tastes muddy or bitter, coarsen slightly.

The two-chamber vapor-pressure method, step by step

1. Set up the two chambers. Insert the filter into the base of the upper chamber, filling the lower bulb with your measured water. Attach the upper chamber loosely at first so trapped air can escape as the water heats.
2. Apply heat to the lower bulb. A butane burner or halogen beam stand both work; the goal is steady, even heat, not a fast boil.
3. Watch the water rise. As the lower chamber’s water approaches boiling, expanding vapor pressure forces it up through the tube into the upper chamber. Once most of the water has transferred, seat the upper chamber firmly.
4. Add your grounds and stir. With the water now in the upper chamber, add your measured, medium to medium-fine ground coffee and stir gently to fully saturate the bed. Full immersion contact begins here.
5. Brew for about a minute. Most siphon recipes call for roughly 45 seconds to a minute and a half of contact time in the upper chamber, with a second gentle stir partway through to keep extraction even.
6. Remove the heat. Pulling the burner away lets the vapor in the lower chamber cool and contract, creating the vacuum that pulls brewed coffee back down through the filter, leaving the spent grounds behind in the upper chamber.
7. Wait for the draw-down to finish. You will hear a distinctive gurgling sound as the last of the coffee is pulled through. Once it stops, detach the upper chamber and pour directly from the lower bulb, which now serves as your carafe.

Total time from first heat to a finished cup runs close to three minutes, matching the 2:30 to 3:30 window this site’s grind chart lists for the method, including the vacuum draw itself.

Common mistakes

Boiling too aggressively is the most common one. A hard, fast boil under the lower bulb pushes water up unevenly and can crack a glass chamber over repeated heat-shock cycles; steady, moderate heat is both safer and produces a cleaner brew. Forgetting to stir when the grounds first hit the water is the second most common mistake, since siphon coffee has no bloom stage the way a pour-over does, an unstirred bed of grounds floating on top of the water extracts unevenly for the whole immersion window. The third is leaving the upper chamber loosely seated once water has finished rising into it; a poor seal lets vapor escape rather than build the vacuum that pulls the coffee back down, leaving liquid stranded in the upper chamber at the end of the brew.

How siphon compares to other methods on this site

Siphon’s reconciled 1:12 to 1:16 range spans a wider gap than most single methods on this site, because it straddles two different brewing philosophies inside one device: a full immersion steep, like French press at 1:12 to 1:17, followed by a filtered draw-down that produces a clarity closer to Kalita Wave’s reconciled 1:16. That hybrid character is exactly why the two sourced guides land in different places: Sprudge’s 1:16 house style leans into the pour-over-like clarity siphon coffee is known for, while My Home Barista’s 1:13 standard leans toward the fuller body immersion brewing usually produces. Neither is brewing the method wrong; they are choosing different points on a real, legitimate range, the same way this site found for Turkish coffee’s 1:8 to 1:12 spread.

Common questions

What is the correct siphon coffee ratio? Between roughly 1:12 and 1:16, coffee to water, depending on house style and strength preference. 1:13, close to 15 grams of coffee per 200 milliliters of water, is a reasonable middle default; 1:12 produces a stronger cup and 1:16 a lighter, more pour-over-like one.

Why do sources disagree so much on siphon ratio? Siphon coffee combines a full-immersion steep with a filtered draw-down, so different guides lean toward either the fuller body immersion brewing typically produces or the clarity filtered coffee typically produces. Both approaches are legitimate; the ratio you choose shifts the cup toward one character or the other rather than one number being correct and the other wrong.

What grind size does siphon coffee need? Medium to medium-fine, distinctly finer than a standard drip grind but noticeably coarser than espresso. One sourced guide compares the texture to beach sand, another to fine table salt; both sit inside the 375 to 800 micron band this site’s own grind chart lists for the method.

Do I need special equipment to brew siphon coffee? Yes. A siphon or vacuum pot setup, typically glass upper and lower chambers connected by a tube with a cloth or metal filter, plus a dedicated heat source such as a butane burner or halogen beam stand. Standard stovetop heat is not part of most siphon designs and is not recommended for glass chambers.

Is siphon coffee stronger than French press? Not necessarily by ratio; the two methods’ ranges overlap. Siphon’s reconciled 1:12 to 1:16 range sits close to French press’s 1:12 to 1:17, covered in our French press ratio guide. What differs is texture and clarity: siphon coffee passes through a filter on its way down, producing a cleaner cup than French press’s metal mesh typically allows through.

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Written by Theo Marsh · Published 30 August 2026