Two ratios, same beans, same time
We used 100 g of a medium-roast Brazilian coffee, ground coarse (roughly 1 mm particles), split into two batches in our 1.2 L Cold Brew Carafe. Batch A used 800 ml water (1:8), batch B used 1200 ml water (1:12). Both steeped at 4 °C for exactly 18 hours and were filtered through the same 180-micron mesh.
What 1:8 delivers
The 1:8 batch produced a true concentrate: thick, intensely chocolatey, built to be diluted 1:1 with water or milk before drinking. Undiluted, three of four tasters found it too intense and slightly bitter at the finish, consistent with the longer contact time between water and a higher concentration of grounds.
What 1:12 delivers
The 1:12 batch was drinkable straight from the fridge, no dilution needed. It was noticeably sweeter and less bitter than the diluted 1:8 batch at an equivalent final strength, which suggests dilution after steeping doesn't fully replicate brewing at a lower ratio from the start.
Our conclusion: brew at 1:12 if you drink cold brew straight, and reserve 1:8 for recipes where you're mixing it into milk-heavy drinks and want headroom to dilute to taste. Steep time matters less than ratio for the bitterness most people complain about.
