What is Tetsu Kasuya's 4:6 method and how does it work?

The 4:6 method is a V60 pour-over technique developed by Japanese barista Tetsu Kasuya, winner of the 2016 World Brewers Cup. It divides the total brew water into two groups: the first 40% (the "4") which determines acidity and sweetness balance, and the remaining 60% (the "6") which controls strength and concentration. Its power lies in its modularity — by adjusting only the number and size of pours within each group, a brewer can precisely tune the cup profile without changing grind size or brew ratio.

The 4:6 method operates on a principle of sequential, controlled extraction. In the standard recipe using 20 g of coffee and 300 ml of water at 93°C, the first 120 ml (40%) are divided into two 60 ml pours spaced 45 seconds apart. The remaining 180 ml (60%) follow in three to five equal portions, also 45 seconds apart. Total brew time targets 3:30 to 4:00 minutes.

The elegance of the system lies in the logic of each group. The first two pours — the "4" — saturate the bed and trigger extraction of organic acids and simple sugars, the most soluble compounds in coffee. By adjusting the ratio between these two initial pours, the brewer directly controls the sweet-acid balance: a smaller first pour (40 ml followed by 80 ml) increases sweetness by delaying early acid extraction; a larger first pour (80 ml followed by 40 ml) produces more brightness and acidity. The "6" pours then control final strength: fewer portions (2-3) produce a stronger, denser cup; more portions (4-5) yield a lighter, more delicate result.

Physically, the method exploits the non-linear relationship between bed saturation and hydraulic resistance. Each pour lands on a partially extracted bed, creating layered rather than simultaneous extraction — a fundamentally different mechanism from continuous-pour techniques. This reduces channeling risk because the bed is never fully submerged in one action, and the grounds have time to redistribute slightly between pours. Kasuya debuted the method at the 2016 World Brewers Cup in Dublin using a natural-processed Ethiopian coffee, winning with a cup that judges described as exceptionally clean and reproducible.

A remarkable fact: the 4:6 method is one of the very few pour-over techniques to receive its own official mobile application, developed by Kasuya himself, which calculates exact pour volumes for any custom recipe. This democratized a technique initially seen as competition-only, bringing structured pour-over methodology to home brewers worldwide.

4:6 Method — base recipe example (20 g / 300 ml)