When you see 1:16, 1:15, or 1:17 in a coffee recipe, the first number is coffee and the second is water, both measured by weight. A 1:16 ratio means 1 gram of coffee for every 16 grams of water.
Translating to actual amounts
For a typical single cup using a V60 or AeroPress, 18 grams of coffee at 1:16 means 288 grams of water. Most drinkers round to 290 for simplicity. For two cups, scale up: 30 grams of coffee at 1:16 is 480 grams of water.
Why ratios matter more than scoops
Coffee beans vary in density. A scoop of light-roasted beans weighs less than a scoop of dark-roasted beans of the same volume. A scoop is also imprecise; it changes with how you fill it. Weight is consistent. A scale that measures to one gram is the single best small upgrade for any home brewer.
Common ratios and what they produce
1:14 to 1:15 Stronger, bolder cup. Suited to French press and darker roasts.
1:16 The default for pour-over and AeroPress. Balanced, with good clarity.
1:17 to 1:18 Lighter, more tea-like. Common for delicate Ethiopian washed coffees.
Espresso ratios are different
Espresso uses a different format. 1:2 in espresso means the brewed shot weighs twice the dry coffee dose: 18g in, 36g out. This is yield ratio, not brew ratio in the same sense. Espresso uses much less water and much more pressure, so the math is calibrated separately.