If your home-brewed coffee tastes different every morning, the problem may not be the beans or the brewer. It may simply be the amount of coffee and water you use.
A coffee-to-water ratio gives you a repeatable starting point. Once you can make the same cup twice, you can adjust it to suit your taste instead of guessing. This guide explains practical ratios for filter coffee, plunger and espresso, with easy measurements for New Zealand home coffee drinkers.
What is a coffee-to-water ratio?
A coffee-to-water ratio compares the weight of ground coffee with the amount of water used to brew it. A ratio of 1:16 means one gram of coffee for every 16 grams of water. Because one millilitre of water weighs approximately one gram, 300 ml of brewing water can be treated as roughly 300 g for everyday coffee making.
At 1:16, a 300 ml brew starts with about 19 g of coffee. You do not need to calculate this in your head every morning: divide the water amount by the second number in the ratio. For 300 ml at 1:16, the calculation is 300 ÷ 16 = 18.75 g.
Quick coffee ratio chart
| Brewing method | Useful starting ratio | Example |
|---|---|---|
| Pour-over or filter | 1:15 to 1:17 | 18–20 g coffee for 300 ml water |
| Plunger / French press | 1:15 to 1:16 | 31–33 g coffee for 500 ml water |
| Espresso | About 1:2 coffee dose to espresso yield | 18 g coffee in, about 36 g espresso out |
These are starting points, not rules. Your grinder, roast, brewer and preferred cup strength may lead you to a slightly different recipe.
Best coffee-to-water ratio for filter coffee
For pour-over, batch brewer or other filter methods, begin near 1:16. This sits in the middle of the practical 1:15–1:17 range and is easy to adjust.
- One small mug, 250 ml: use about 16 g of coffee at 1:16.
- One larger mug, 300 ml: use about 19 g.
- Two mugs, 500 ml: use about 31 g.
- A 750 ml brewer: use about 47 g.
If the cup seems thin even though the extraction tastes clean, try a stronger ratio such as 1:15 by using a little more coffee. If it feels heavier than you enjoy, move towards 1:17. Change only the ratio first; if the coffee tastes sour, bitter or astringent, grind size and brew time may be the more relevant controls.
For a balanced everyday option, Fur-ever Roast is a full-bodied 100% Arabica blend from Brazil and Honduras. CaffTail describes it as smooth, chocolatey and balanced, and the current product is available as whole bean or ground in 200 g and 500 g sizes.
Best ratio for plunger coffee
A plunger, also called a French press, usually suits a ratio around 1:15 to 1:16. For a 500 ml plunger, start with 32 g of coffee. For a one-litre plunger, start around 63–67 g.
Be careful with the number printed on a plunger box. A manufacturer’s “cup” may be much smaller than the mug you actually use. Measuring the water you pour into your own brewer is more reliable than assuming an eight-cup plunger will serve eight full mugs.
A simple plunger recipe
- Warm the plunger and tip out the water.
- Add 32 g of coarsely ground coffee for 500 ml of water.
- Pour in the water, making sure all grounds are wet.
- Allow the coffee to steep, then press slowly.
- Pour the brewed coffee out rather than leaving it sitting on the grounds.
If you prefer a bold, dark-chocolate-led cup, Purrk Up is CaffTail’s medium-dark, full-bodied, high-caffeine blend. It is currently available in whole-bean and ground formats, so choose the option that fits your home setup.
Espresso ratios work differently
For espresso, the most useful ratio compares the dry coffee dose with the liquid espresso yield—not the full amount of water held inside the machine. A common starting point is 1:2: for example, 18 g of ground coffee in the basket and about 36 g of espresso in the cup.
Use a scale beneath the cup and stop the shot when you reach the target yield. Then assess the result. A shorter yield can taste more concentrated; a longer yield can taste more diluted and extracts more from the grounds. Shot time, grind and puck preparation also matter, so keep the dose and yield stable while adjusting the grind.
Milk drinks can make an under-strength shot disappear. If a flat white lacks coffee flavour, check your espresso recipe before simply adding more coffee to the basket. A consistent 1:2 starting point makes troubleshooting far easier.
How to make coffee stronger without making it bitter
“Strong” can describe concentration, roast character, caffeine or simply a flavour preference. If you want a more concentrated filter or plunger brew, use slightly more coffee while keeping the water amount fixed. Moving from 1:17 to 1:15 is a controlled adjustment.
Do not automatically grind much finer to create a stronger cup. A finer grind increases extraction and can push flavour towards bitterness or dryness if the brew is already extracting well. Change one variable at a time:
- Keep your water amount and grind unchanged.
- Add one or two grams more coffee.
- Taste the result.
- Record the recipe if it is better.
The same principle works in reverse. If the cup is too concentrated but otherwise tastes pleasant, use a little less coffee or more water rather than changing several parts of the recipe together.
Do you need a coffee scale?
You can brew without one, but a small digital scale removes the uncertainty caused by scoops. Coffee beans vary in size and density, and a level spoon is not always level. Measuring both coffee and water in grams lets you repeat a recipe and understand what changed.
If you do not want to weigh coffee at all, CaffTail Drip Coffee Bags provide a pre-portioned 10 g serving and need only a cup and hot water. Current options include Fur-ever Roast, Purrk Up, Cat Nap Decaf, Birthday Roast and Single Origin Panama in five- or ten-bag packs.
Choosing a ratio for decaf
Decaf does not require an entirely different ratio. Start with the same recipe you would use for regular coffee, then adjust for taste. If you want an evening coffee with a rich dark-roast profile, Cat Nap Decaf is currently available whole bean or ground in 200 g and 500 g sizes. Its listed profile includes milk chocolate, vanilla, brownie, graham cracker and toasted walnut, with low acidity and a full, velvety body.
Common ratio mistakes
Measuring beans but not water
A carefully weighed dose will not give consistent results if the water amount changes each time. Put your brewer on the scale and weigh the water as you pour.
Confusing drink size with brewing water
Ground coffee retains some water, so the finished drink will weigh less than the water poured in. Build the recipe from brewing water, not the final volume in the mug.
Changing everything after one disappointing cup
If you alter ratio, grind, temperature and brew time together, you will not know which change helped. Keep notes and adjust one variable at a time.
Frequently asked questions
How much coffee should I use for one cup?
For a 250 ml filter coffee, about 15–17 g is a practical range; 16 g gives a simple 1:16 starting ratio. For a 300 ml mug, start around 19 g.
How much coffee should I use for 500 ml of water?
Use about 31 g at 1:16, or roughly 33 g for the stronger 1:15 ratio. Both are useful starting points for a plunger or larger filter brew.
Is two tablespoons of coffee enough for one mug?
It may be, but tablespoons are less consistent than weight. If your results vary, weigh the same coffee once and use that measurement as your repeatable recipe.
What ratio makes the strongest coffee?
A smaller water number means a more concentrated brew: 1:15 is stronger than 1:17 when everything else stays equal. That does not automatically mean it contains the most caffeine or tastes best.
Start with 1:16, then make it yours
For most filter and plunger brews, 1:16 is an uncomplicated place to begin. Weigh the coffee, weigh the water and taste before changing anything. Once you find the ratio that suits your mug and brewer, save it on your phone or beside the coffee machine.
Choose an in-stock CaffTail coffee that matches your preferred flavour—balanced Fur-ever Roast, bold Purrk Up or dark-roast Cat Nap Decaf—then use the same recipe for several brews. Consistency is what turns a ratio from a number into a genuinely better daily cup.