Posted by Matthew on 5/30/2025 to
Coffee Education
When Goldilocks lifted the latch on the 3 Bears’ front door and entered, she did not find three bowls of porridge on the table, contrary to popular belief. Instead she found three steaming cups of coffee. Bears are big coffee drinkers, especially in the springtime.
The biggest cup that Goldilocks tried was too strong and bitter. The middle-sized cup was too weak and sour. But the little cup was just right. She closed her eyes in bliss and sipped to her heart’s content.
If you’re looking to home-brew a cup of coffee in the Goldilocks Zone, start with a high-quality, fresh-roasted coffee. Then consider the 6 key variables that go into brewing the perfect cup.
1) Ratio
Most coffee we drink is 98.5% water. Even so, the coffee-to-water ratio is really important. Too little coffee in your water and you have a weak, sad cup of joe. Too much and it will stick to your ribs. The good news is that you can always add water to your brew once it's completed. Just keep in mind that you can’t take it away. So when in doubt, aim for a stronger brew and then adjust to your taste by adding hot water.
2) Water Quality
Most water, including municipal tap water, makes a fine cup of coffee. Be mindful of hard water with a high mineral content, especially iron, which can adversely flavour your cuppa. Some people don’t like coffee made with softened water, either. Technically speaking, the ideal range is 75 to 250 parts per million of total dissolved solids (TDS). Distilled water has none, while some tap water has too much. But most water is just right. Aim for the closest thing to mountain spring water you can get and you’ll do just fine.
3) Water Temperature
Whatever water you’re using, make sure it’s right off the boil, approximately 98 degree Celsius. Lower-temperature water will result in a brew with a slightly sour taste and a longer brewing time. The exception to this rule is when you’re making cold brew. See our blog on {how to make great cold brew at home}.
4) Grind Size
There is a correct grind size for each brewing technique. French Press requires a coarse grind, while Espresso grind consistency is not far from powder. The size of the grind is calculated to optimally extract the favourable flavours for your chosen brewing method.
5) Turbulence
This is the amount of ‘mixing’ that water does with coffee during the brewing process. Percolation, which sends water into a basket full of grounds over and over again until it has achieved the right strength, introduces the highest degree of turbulence of any brewing method.
The turbulence involved in cold brewing is low, but the brew time (12 to 15 hours) is so long that there’s lots of water/coffee ‘mixing’ there, too. A pour-over is an example of low turbulence.
A good rule of thumb is to try and plan the exact amount of turbulence that you introduce. With French press, give it a quick stir but no more before letting it settle; with a pour-over simply pour a fine stream of piping hot water over all ground coffee so as to soak it thoroughly, as per instructions.
6) Brewing Time
This is more a measure of consistency than the other factors. The determining factors in brewing success are coffee type, quality and roast; coffee-to-water ratio; turbulence; surface area (a factor of grind coarseness); water quality; and temperature. Everything being equal, brew time should always be the same. But when other factors change, brew time can shift, too. If your grind is too coarse, for example, you will want to keep that perc going a couple minutes longer.
Experiment, record, perfect.
Our advice is to play around. Choose a brewing method, an appropriate bean, then work on your brew until you have it just the way you want it. You might want to keep a pen and pad (or iPad) on the counter to keep a record of what you’ve changed each day. Most home brews will turn out even better than your favourite coffee shop, as you are brewing your coffee exactly how you like it.
Happy home roasting!