Chemex Coffee Ratio

Chemex takes more coffee in absolute terms than most pour-over drippers — a 30g typical dose, against 20g for a V60 — but the ratio itself sits at the higher, lighter end of the filter-coffee range. Balanced is 1:17, moving to 1:15 for a fuller cup or stretching to 1:18 for something more delicate. Those two facts aren't in tension; a bigger dose brewed into proportionally more water is how Chemex reaches the larger batch sizes it's built for.

The filter is why the ratio runs light

Chemex's bonded paper is considerably thicker than a standard cone filter, and that thickness does real extraction work: it holds back more fine particulate and more of the coffee's oils than a thin V60 or Kalita filter, which is what gives Chemex coffee its characteristically clean, almost tea-like clarity. Slower drainage through that thick paper also means more total contact time than a fast-draining cone at the same grind, which is part of why Chemex recipes lean toward the higher end of the ratio range — a lower relative dose compensates for the extra time the water spends in contact with the bed.

Working the ratio at Chemex's actual batch sizes

A 30g dose at 1:17 calls for 510ml of water; at 1:15, 450ml; at 1:18, 540ml. Because Chemex is built for entertaining and multi-cup batches more than a single mug, scaling up matters more here than on a one-cup dripper: doubling to a 60g dose keeps the same three water figures doubled (1020ml, 900ml, 1080ml), and the ratio calculator handles any in-between batch size directly.

Grind has to move with the filter, not just the ratio

Because that thick paper already restricts flow, a Chemex grind needs to run coarser than a V60 grind even at a similar ratio, or the two restrictions compound into a stalled, bitter brew. If you're moving a recipe from a V60 to a Chemex and keeping the same grind setting, expect a slower drawdown and likely a more bitter cup — the fix is coarsening the grind, not changing the ratio further.

Bigger batches change more than just the math

At Chemex's typical dose range, the coffee bed itself gets tall enough in the cone that the pours have to be more deliberate about reaching the edges evenly — a common failure on a full Chemex batch is a dry ring of ungrounds around the rim from pours that stayed centered, which shows up as sourness in the cup despite the ratio being correct on paper. That's a technique issue, not something more water or less coffee fixes.

Moving off balanced for a bigger batch

Reach for 1:15 with a darker roast or when serving with milk, where a slightly fuller body holds up better. Reach for 1:18 with a light, naturally processed coffee where you want maximum clarity and don't want the batch to read as heavy. If a batch at any of these three settings tastes wrong in a specific way rather than simply too strong or weak, that's a grind or pour-technique question — see slow drawdown first, since Chemex is the method most likely to stall if the grind doesn't account for the filter.

For bloom timing, the specific pour schedule a full Chemex batch needs, and the grind adjustment this page only touches briefly, see the full Chemex guide.