Cold Brew vs. Cold Drip: The Difference
Cold extraction tastes different — milder, sweeter, less acidic. But Cold Brew and Cold Drip aren't the same thing. Play through here how method (immersion or percolation), ratio, grind size, time and roast shape the result.
The sliders: Method is a switch between Cold Brew (immersion) and Cold Drip (percolation). Ratio runs from 1:4 to 1:16 in half steps and means parts of water per part of coffee, by weight — so 1:8, for example, is 60 g of coffee to 480 g of water. Grind size is a relative scale from 0 to 100 without a unit: 0 is coarse, 100 is fine. These are not microns. Contact time has a real unit: 2 to 24 hours. The slider stops at 24 h, and that's deliberate — 24 h is also the upper end of what we recommend (12 to 24 h). You can't play through longer steeps here. Roast has only two levels, medium and dark; there is no light roast in this tool.
The results: Strength / concentration, acidity / liveliness, body / smoothness, aromatics and caffeine are indices from 0 to 100, not measurements and not lab results. This applies to one line in particular: “Caffeine %” is not a caffeine content. The number doesn't tell you how many milligrams of caffeine are in the glass, but how far the caffeine extraction has progressed: 0 % means “almost nothing dissolved yet”, 100 % means “extracted everything there is to extract”. A thin 1:16 brew and a thick 1:4 concentrate can both sit at 100 % and still differ completely in strength. How strong your drink really turns out is shown in the strength / concentration line.
The basis: That caffeine and chlorogenic acid reach equilibrium at room temperature after about 6 to 7 hours has been measured (Fuller and Rao 2017). The curves the tool uses to trace this are modelled on that finding but not derived from it: for immersion it calculates with a saturation curve that stands at around 63 % after 6 h, around 86 % after 12 h and around 95 % after 18 h; for Cold Drip with a straight rise that reaches 100 % after 9 h. These two time constants — the 6 and the 9 — are assumptions and not backed by evidence. The same goes for the assumption that a dark roast yields 10 % less caffeine; why that only holds when dosing by volume is explained further down. So the 63, 86 and 95 per cent are model values: estimated, not measured. A model that shows the direction — and it shows that reliably.
This is a simulator. It calculates with a simplified model and shows you how things are connected — no measurements and no assurances. What ends up in your cup depends on your machine, your water, your beans and the way you work.
Our recommendations reflect our experience from consultations, courses and the showroom. They are non-binding and come without guarantee. We accept no liability for any damage arising from their use. If in doubt, what your manufacturer says in the user manual applies.
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EstimateOn the bars just above: strength, acidity, body, aromatics and caffeine are indices from 0 to 100 from our model — estimated, not measured, and not a lab result for your brew. “Caffeine” here is not a caffeine content in milligrams but the progress of caffeine extraction. The numbers show you the direction your drink is moving in — not how it will taste.
Cold Brew vs. Cold Drip — the difference
Cold Brew (immersion): The coffee sits fully submerged in the cold water the whole time and slowly saturates it. Result: soft, sweet, full-bodied, low acidity. Cold Drip / Kyoto (percolation): Cold water drips slowly through the coffee bed, with fresh solvent constantly coming through. Result: clearer, livelier, more acidity and aromatic complexity.
Cold also means slow. At room temperature, caffeine and chlorogenic acid only reach their equilibrium after about 6–7 hours (they rise fastest in the first ~3 hours). And importantly: Cold Brew contains less titratable acid than hot-brewed coffee at a comparable pH — which is why it tastes milder. Here, time is real physics (it makes up for the slow cold kinetics) — but the decision is still made by concentration, ratio and taste.
We need to correct a statement that used to be on this page: “Medium roasts deliver more caffeine than dark ones.” That's true for chlorogenic acid — it breaks down heavily during roasting; the darker the roast, the less remains. For caffeine, it isn't true as stated. Caffeine is heat-stable well beyond roasting temperatures and survives roasting almost unchanged. So if you dose by weight, the difference between medium and dark is very small. It only becomes noticeable when you dose by volume — with a spoon or measuring cup: dark beans have lost more mass and expanded further, so they're lighter, and the same spoon holds less coffee and therefore less caffeine. For “dark”, the tool above calculates with 10 % less caffeine. That corresponds to dosing by volume, not by the gram.
Sources (scientific): Fuller & Rao (2017), “The Effect of Time, Roasting Temperature, and Grind Size …”, Scientific Reports (kinetics & equilibrium ~6–7 h); Rao & Fuller (2018), “Acidity and Antioxidant Activity of Cold Brew Coffee”, Scientific Reports (less titratable acid than hot brew); on the heat stability of caffeine and the density difference between light and dark roasts: roasting chemistry fundamentals, including Illy and Viani (eds.), Espresso Coffee: The Science of Quality (2nd edition 2005). The time constants and weightings in the simulator's calculation engine are assumptions, not measurements.
What you need
For Cold Brew (immersion), a vessel like the Hario Mizudashi, the Varia Cold Brew Bottle or a French Press is all you need; for Cold Drip, a drip tower. You'll find both — and the matching filter and Cold Brew vessels — with us. A Varia grinder delivers the evenly coarse grind. Plus fresh beans (a medium roast gives more chlorogenic acid than a dark one; for caffeine, the difference by weight is small).
Frequently asked questions
What's the difference between Cold Brew and Cold Drip?
Cold Brew is an immersion: the coffee sits in the water the whole time — the result is soft, sweet and full-bodied with low acidity. Cold Drip (Kyoto) is a percolation: water drips slowly through the bed — the result is clearer, livelier and more aromatically complex.
How long does Cold Brew need to steep?
At room temperature, caffeine and chlorogenic acid reach equilibrium after about 6–7 hours. Many people still let a concentrate steep for 12–24 hours and dilute it afterwards. There's no right or wrong — dilute to taste. The time slider in the simulator stops at exactly 24 hours, the upper end of this recommendation; you can't play through longer steeps there.
Is Cold Brew less acidic?
Yes. The pH is similar to that of hot-brewed coffee, but Cold Brew contains less titratable acid — which is why it comes across as milder and less acidic.
Which grind size and which roast?
A fairly coarse grind suits Cold Brew. When it comes to roast, it pays to look closely: medium roasts really do deliver more chlorogenic acid — it breaks down heavily in dark roasting. For caffeine, that only holds if you dose by volume; by weight the difference is very small, because caffeine survives roasting almost unchanged. Dark roasts, on the other hand, taste rounder and more chocolatey.
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