The AeroPress
The AeroPress is a cylinder in which coffee is steeped before the brew is driven through a filter by pushing a plunger, like a syringe. Invented to quickly make a single good cup, it has become a testing instrument for amateurs and the subject of a world championship.
How does the AeroPress extract coffee?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
The cylinder is set on the cup, the paper filter held under the cap. Into it go 16 to 18 g of medium-fine ground coffee, then water at 85 °C according to the manufacturer: immersion begins, and this is where most of the extraction happens.
Read the stages without animation
- Wet the groundsThe cylinder is set on the cup, the paper filter held under the cap. Into it go 16 to 18 g of medium-fine ground coffee, then water at 85 °C according to the manufacturer: immersion begins, and this is where most of the extraction happens.
- StirThree seconds with the paddle bring every particle into contact with the water: no more dry pockets. For Jonathan Gagné, this ease of stirring the coffee slurry is the device's great asset.
- Insert the plungerThe manufacturer has you wait thirty seconds, sixty for pre-ground coffee. The plunger goes in: its seal closes the cylinder, and a pocket of air stays trapped between the seal and the liquid. That compressed air will push the coffee.
- PressWith a gentle, steady push, without forcing, the plunger is lowered: the compressed air drives the liquid through the filter and the cap, until the air hisses. This short percolation finishes the extraction, and the filter holds back the particles.
- EjectWith the cap removed, the plunger pushes the puck of grounds out of the cylinder and wipes it on the way: the device is clean for the next cup. With 18 g of coffee, the chamber leaves room for only about 260 mL of water, a ratio close to 1:14.
To remember: The AeroPress is an immersion finished by a short percolation: the compressed air under the plunger pushes the brew through a filter.
In history: Alan Adler filed the patent for his filtering press on May 18, 2005; it is the compressed air under the plunger, he writes, that drives the liquid through the cap.
Read the full article and its sources ↓History
Alan Adler was not a coffee man. According to the company that owns the product today, he had been inventing since the age of thirteen, founded Superflight in 1984 to sell his flying rings, including the Aerobie, and renamed the company Aerobie in 2005 (source 2). Disappointed by home coffee makers, he started from a conversation about the difficulty of making a single good cup, studied the variables of steeping, and used air pressure to shorten the contact time and reduce bitterness (source 2).
US patent 7,849,784, “Coffee or tea filtering press,” filed on May 18, 2005 and granted on December 14, 2010, describes the object almost part by part: a hollow cylinder open at both ends, a removable perforated cap that closes the bottom and holds a filter, a plunger pushed in from the top, a rest that sets the press on the cup, and a paddle for stirring (source 1). Adler specifies that it is the compressed air under the plunger that drives the liquid through the cap, and that the same plunger, pushed further once the cap is removed, ejects the puck of grounds while its seal wipes the cylinder (source 1). He gives the dimensions that work very well in his view: about 2.25 inches of inside diameter and 5 inches long, that is roughly 57 and 127 mm (calculated) (source 1).
After two years and more than thirty prototypes, the AeroPress was presented at Coffee Fest in Seattle in November 2005, according to the manufacturer (source 2). The patent was assigned in 2017 to Aerobie, then to AeroPress Inc., a California company; Google Patents still lists it as in force, with an adjusted expiration of June 1, 2027 (source 1). The company was bought in the summer of 2021 by Tiny Ltd (source 2).
The motion
The manufacturer's instructions are short: set the chamber on a cup, put in 16 to 18 g of medium-fine ground coffee or one heaped scoop, pour water at 85 °C up to mark 4, stir for three seconds, wait thirty seconds, then press the plunger with a gentle, steady push, without forcing, until the air hisses (source 3). With pre-ground coffee, which is coarser, the wait goes up to sixty seconds (source 3).
Amateurs have made this base a testing ground. Gagné notes that, to keep a coffee bed thick enough and avoid uneven flow when pressing, a dose of 18 g leaves room for only 260 mL of water, a ratio close to 1:14, and that his cups often had the profile of an under-extracted coffee (source 4). He obtained a sweetness that astonished him by steeping at 99 °C for ten minutes, a duration he judges unreasonable at the counter but acceptable at home (source 4). The ease of stirring the coffee slurry, and so of bringing every particle into contact with the water, is in his view the device's great asset (source 4).
The settings
- GrindMedium-fine, setting 11 to 13 on a Baratza Encore grinder according to the manufacturer (source 3).
- Dose16 to 18 g or one heaped scoop (source 3).
- Brew ratioAbout 1:14 at most with 18 g, the chamber holding only about 260 mL of water (source 4).
- Temperature85 °C according to the manufacturer (source 3); Gagné goes up to 99 °C (source 4).
- TimeThree seconds of stirring and 30 to 60 seconds of waiting before pressing (source 3); up to ten minutes at Gagné's (source 4).
- PressureManual and not quantified: it is the compressed air under the plunger that pushes the liquid (source 1).
What it has going for it
- It makes a single cup, quickly, which is what it was designed for (source 2).
- It is easy to stir, which brings all the grounds into even contact with the water (source 4).
- The plunger ejects the grounds as a puck and wipes the cylinder on the way, which reduces cleaning to a single motion (source 1).
- Contact time can be set freely, from thirty seconds to ten minutes, which makes it a testing instrument for understanding extraction (sources 3 and 4).
- Gagné says he enjoyed it a great deal, especially when traveling (source 4).
What is held against it
- Capacity is small: with 18 g of coffee, there is room for only about 260 mL of water (source 4).
- This capped ratio pushes toward under-extracted cups, bright in acidity but poor in sweetness on light roasts (source 4).
- The manufacturer advises against pressing hard, and pushing a concentrated liquid through the bed can pull out astringent flavors (sources 3 and 4).
What it gives in the cup
The AeroPress is a hybrid method, and its cup leans toward immersion. Gagné groups it with the siphon among the immersion methods: the final press is a percolation, but most of the extraction happens while the grounds sit in the water, and the taste shows it (source 5). He also suspects that the push of the plunger leaves very little liquid between the particles, which changes the calculation of extraction yield from the measured concentration (source 6).
No published study giving the concentration of an AeroPress cup was found. What Gagné describes comes down to tendencies: short, low-temperature recipes give a bright acidity and little sweetness on light coffees, long, near-boiling steeps a pronounced sweetness, and pressing an already saturated infusion can still make the cup flat and astringent (source 4). The filter held under the cap holds back the particles (source 1).
Anecdotes
- Before coffee, Adler was known for a toy: his Aerobie flying ring set a Guinness world record for the longest throw of an object, 406 meters, according to the manufacturer (source 2).
- The AeroPress world championship, organized by amateurs, was born in 2008 in Oslo from an idea of Tim Wendelboe and Tim Varney; the first edition had only three competitors and was won by the Norwegian Anders Valde. In 2023, more than 5,000 competitors faced off in 178 national and regional events, according to the manufacturer (source 2).
The sources for this sheet
- Alan J. Adler, US patent 7,849,784 B2, “Coffee or tea filtering press,” filed May 18, 2005, granted December 14, 2010; assignments and status according to Google Patents · online · primary
- AeroPress Inc., “About AeroPress, Inc. and Alan Adler,” accessed October 21, 2026 (manufacturer) · online · manufacturer
- AeroPress Inc., “How to use,” accessed October 21, 2026 (manufacturer) · online · manufacturer
- Jonathan Gagné, “Reaching Fuller Flavor Profiles with the AeroPress,” Coffee ad Astra, September 7, 2021 · online · secondary
- Jonathan Gagné, “Why do Percolation and Immersion Coffee Taste so Different?” Coffee ad Astra, July 16, 2019 · online · secondary
- Jonathan Gagné, “A More Accurate Way to Calculate Average Extraction Yield,” Coffee ad Astra, February 20, 2019 · online · secondary