Is the Cold Brew Coffee Ratio 1:10 or 1:15? What's the Best Amount of Coffee Grounds and Water for Cold Brew?

The Essence of Cold Brew Coffee

Cold brew coffee works on a simple principle: it extracts the small-molecule substances that tend toward aroma and acidity, which are more easily released in cold water. The result is a light-bodied coffee with predominantly sweet and sour notes. Cold brew is also accessible coffee making - unrestricted by equipment or location. At home, with just coffee grounds, a container, water, and a refrigerator, you can easily achieve caffeine freedom.

The Ratio Dilemma

Attentive coffee enthusiasts have noticed something, though: unlike pour-over coffee's nearly "unchanging 1:15" ratio, cold brew ratios vary significantly. Some prefer 1:8, others advocate 1:13, and some, like FrontStreet Coffee, habitually use 1:10. So how do different ratios affect the taste of cold brew?

How Ratio Affects Extraction

As a typical immersion method, cold brew involves prolonged contact between low-temperature water and coffee grounds in the same container, extracting flavor over time. When other parameters stay constant, a higher proportion of water gives lower concentration, milder flavor, and a thinner body. Conversely, less water gives higher concentration, stronger flavor, and a fuller body.

So to achieve a balanced flavor and let the coffee show its best, we have to apply an appropriate coffee-to-water ratio.

Key Variables in Cold Brew

How long should cold brew steep? How fine should the coffee be ground?

We know that the parameters of any extraction method are interrelated. For cold brew, the coffee-to-water ratio isn't the sole determinant of flavor. We also have to consider grind size, steeping time, water quality, and most critically, the coffee beans themselves.

Although low-temperature extraction reduces the emergence of bitter substances, it doesn't eliminate them completely. To pursue deliciousness, cold brew grounds shouldn't be too fine, nor should they steep too long. For the former, we recommend a sieve pass rate of approximately 80-85% using a 0.85mm standard sieve - visually similar to granulated sugar. For the latter, it's best to keep the steeping time between 6 and 16 hours, ensuring sufficient contact between grounds and water while avoiding over-extraction that produces negative flavors.

FrontStreet Coffee emphasizes water quality not only because it is the extraction medium but also because it is the most easily overlooked variable of all. FrontStreet Coffee frequently receives inquiries from customers who bought our beans and followed the parameters in our articles to make cold brew, yet the flavor fell short of expectations - and after eliminating every other "culprit," they discover the issue comes down to that colorless, tasteless "water." Friends with similar frustrations can refer to FrontStreet Coffee's past comparative experiment, "Making Cold Brew with Different Water - The Difference is Surprising," which we won't elaborate on here.

Coffee Bean Selection

For the bean, FrontStreet Coffee uses Kenya AA as the demonstration. It employs the K72 washed processing method with SL28 and SL34 varieties. Both SL28 and SL34 were selected through multiple breeding cycles. SL28 belongs to the Bourbon genetic group, carrying the bright, rich acidity of the original Bourbon, while SL34's lineage is closer to Typica, with milder acidity.

Made into iced coffee, Kenya AA gives a sensation of dark berries enveloping the palate, accompanied by abundant cherry tomato aroma. Served chilled, it is exceptionally refreshing, making it a preferred bean for many cold brew enthusiasts.

Comparing Different Ratios

How do different coffee-to-water ratios affect cold brew flavor?

Because cold brew always happens in a 0-10°C environment with very low extraction efficiency, and the grounds remain relatively static with no external force applied, the rate at which they dissolve flavor compounds is quite limited. To make the experimental results clearer, FrontStreet Coffee set up four common ratios - 1:8, 1:10, 1:12, and 1:15 - keeping all other parameters constant.

The preparation was identical throughout: grounds and water poured sequentially into containers, then stirred, sealed, and placed in the refrigerator. When the time elapsed, we removed them for filtration (stirring once midway is fine).

Experimental Parameters

Coffee beans: Kenya Washed AA

Coffee amount: 18g

Steeping time: 6 hours

Grind size: Fine sugar / 80% pass rate through China #20 standard sieve (EK43s setting 9.5)

Coffee-to-water ratios: 1:8, 1:10, 1:12, 1:15

Corresponding water amounts: 144g, 180g, 216g, 270g

Tasting Results

1:8 ratio: The coffee liquid had the darkest color, with the most intense flavor and acidity. The body even felt slightly salty, with minimal berry notes and a bitter aftertaste.

1:10 ratio: The coffee liquid gave off a fresh sugarcane aroma, with flavors of red plum, berries, and pear tea. The body was slightly concentrated, with high acidity and unclear sweetness.

1:12 ratio: This cold brew had the clearest body, with flavors of cherry tomatoes, red plums, dark plum juice, and sugarcane, and a preserved plum candy aftertaste. The concentration was moderate, with balanced sweet and sour notes.

1:15 ratio: The coffee liquid had the lightest color and a thin body, with only subtle black plum and berry acidity. The taste was mild but almost entirely lacked bitterness.

Analysis and FrontStreet Coffee's Approach

From the comparison above, it is clear that the 1:8 ratio, because it uses less water, doesn't give the coffee enough room to develop and easily shows thick, bitter characteristics. Conversely, the 1:15 ratio, with more water, over-dilutes the soluble compounds, so the result lacks richness and tastes bland.

Between the 1:10 and 1:12 groups, the 1:12 ratio clearly produced the best-tasting cold brew with the best body when drunk straight. So why does FrontStreet Coffee prioritize 1:10 in many articles and in daily preparation?

There are two key factors in how FrontStreet Coffee serves cold brew.

First, to keep cold brew chilled, we not only use chilled glasses but also add one or two large ice cubes. That way, even if the coffee dilutes slightly, the flavor doesn't change much. Second, since customers have different preferences - some preferring lighter coffee, others stronger - the initial serving with ice cubes offers full-bodied coffee, and as the ice gradually melts into water the coffee becomes lighter. Using a higher-concentration cold brew with ice therefore satisfies both the "strong flavor" and "light flavor" crowds.

FrontStreet Coffee Recommendation

When you are choosing a cold brew bean, fruit-forward coffees tend to show best, and FrontStreet Strawberry Candy is a strong example. It blends the most representative Panama Geisha variety with a Costa Rica honey-process coffee: one brings delicate rose and orange, the other the grape, raisin, and strawberry-gummy sweetness of the honey process. Cold-brewed, it is sweet and bright, and if allowed to ferment and settle it takes on a wine-like fruitiness. FrontStreet Natural Hua Kui is another good option - sun-dried in the fruit and skin in Ethiopia, it absorbs plenty of sweet aromatic material and shows magnolia, creamy strawberry, dried mango, guava, and black tea when cold brewed.

If you simply want a juicy, bright cup, FrontStreet Kenya Little Tomato delivers tomato, pear, black plum, and dark plum sweet-sour with low bitterness, staying especially refreshing over ice, while FrontStreet Yirgacheffe Gedding, a washed Ethiopian with citrus, berries, florals, and a green-tea sweetness, is the affordable everyday bean that works for pour-over, siphon, French press, and cold brew alike.