Coffee extraction is a balance between concentration (TDS) and flavor separation. Here is how your ratio controls both.
The Magic of 60g per Liter (1:16.67)
The Specialty Coffee Association (SCA) Golden Cup standard specifies 55g to 65g of ground coffee per 1,000ml of water. For home brewers using gram scales, 1:16.67 (15g coffee to 250g water) provides the cleanest balance between bright acidity and rich body.
If you prefer a heavier, chocolatey cup, shifting down to 1:15 concentrates the brew. If you are brewing delicate washed Ethiopian or Kenyan coffees, opening up to 1:17 or 1:18 highlights subtle floral aromatics without astringency.
Why Grounds Absorb Twice Their Weight in Water
A dry coffee ground acts like a porous sponge. Cell walls and cellulose capillaries hold roughly 2.0 to 2.2 grams of liquid per gram of dry grounds. That means when you pour 250g of water over 15g of coffee, approximately 30g of water stays behind in the filter bed, yielding a 220g drink.