Hacking Your Brew - Brewing Coffee By Weight

One of the most effective changes you can make to your brewing method is to weigh both your coffee and your water.  In a previous blog post titled "Brewing By Weight" I touched on the importance of brewing by weight and not volume, i.e. using grams or ounces not tablespoons and liters.  This post goes into more detail and hopefully answers any questions on exactly how to brew by weight.

Brewing by weight is more accurate for the following reasons:

  • Unless you're using a graduated cylinder to measure the volume of water, it's very difficult to get a truly accurate measurement.
  • Coffee bean size varies greatly from coffee to coffee and the beans aren't solid; there is a lot of airspace inside the bean.  Margogipe beans, for example, are affectionately called elephant beans because of their size.  A cup of larger beans produces less ground coffee than a cup of smaller beans.  Imagine filling a trashcan with balloons.  You can get more balloons in the can if the balloons are smaller.  Therefore brewing by coffee weight in grams is better than brewing by coffee volume in tablespoons or scoops.

Stick with the same unit of measure for everything.  That makes the math easier.  Instead of trying to use fluid ounces and grams or ounces, you should stick to one unit.  There are just over 28 grams in one ounce. Because grams are the smaller unit, they are more accurate.

Use digital scales.  Digital scales are dirt cheap anymore and are relatively precise, certainly enough for our needs.  You want the accuracy of your scales to be sub-gram, which is reported such as .1 gram, or accurate within a tenth of a gram.

The next step will only need to be done once.  You'll need to determine the water weight needed to fill your decanter.  This determines the maximum amount of brewed coffee the decanter will hold.

  1. Begin by placing the decanter on the scales then turning them on.  This should automatically zero, or tare the scales with the decanter.  If not, press the zero/tare button to do so.
  2. Fill the decanter with water.  The weight shown is the total amount of water you can add to brew your coffee.

Now that you have that information, we can brew:

  1. Start your kettle boiling.
  2. Using the number from above, determine your water-to-coffee ratio, which should normally be in the range of 16 - 20:1 grams of water to coffee.  For example, if your decanter holds 900 grams of water, to brew with an 18:1 ratio, you'll need 50 grams of coffee (900 ÷ 18 = 50).  There is more detail on the brew ratio in the blog post titled Coffee Brew Ratio
  3. When the water reaches a hard boil, turn the heat down (not off) and start grinding your 50 grams of coffee
  4. Place your brewing apparatus on the scales and pre-wet the filter then pour out that water.
  5. Add your ground coffee to the filter
  6. Turn on the scales and make sure they automatically zero or tare, if they don't, use the zero/tare button
  7. Add enough water to wet all the grounds.  Around 70 - 80 grams of water should do for 50 grams of coffee.  It doesn't have to be precise, just enough to wet all the grounds
  8. Let the coffee bloom for a few seconds
  9. Begin pouring water in circular motions
  10. Add in two or three phases, as needed until you've added 900 grams of water.
  11. Enjoy!

Continue Learning: Looking for more how-to articles or articles about roast science? Then check out this page for more!

Michael C. Wright

Michael is an American expat living in Singapore where he writes about many things coffee-related. A roaster by trade, Michael is also exploring coffee production and how to improve the lives of those who produce the noble bean.