French Press Ratio: The optimal brew ratio for each roast level

The brew ratio is the simplest lever for consistently good French press coffee . With the right coffee-to-water ratio, you determine the strength, body, and clarity – tailored to the bean, roast level, and personal taste. In this guide, you'll learn what 1:15–1:17 actually means, why the immersion method has specific rules, and how to quickly convert your coffee quantity in the French press into grams per liter. You'll also find recommendations for each roast level, adjustments for grind size , brewing time, and temperature, common mistakes with their fixes, and a handy mini coffee calculator.

Brew ratio explained briefly: What does 1:15–1:17 mean?

The brew ratio describes the ratio of coffee to water. A ratio of 1:16 means 1 part coffee to 16 parts water. Practically speaking, this is about 62–63 g of coffee per 1 liter of water. For the French press, a brew ratio of 1:15 to 1:17 has proven effective.

• 1:15 ≈ more powerful, more body, potentially less clarity
• 1:16 ≈ balanced, often an ideal starting point
• 1:17 ≈ lighter, clearer, less body

Note: A ratio is a starting point – you should fine-tune it with grind size , brewing time and temperature.

The brew ratio thus influences strength, body, and clarity.

• Strength: Less water (lower ratio) increases the concentration, the coffee tastes stronger.
• Body: A higher amount of coffee plus the metal filter of the French press results in a richer, fuller mouthfeel.
• Clarity: A higher ratio (more water) and longer, gentle extraction often bring more clarity – as long as it is not underextracted.
• Extraction rate: At the same time and temperature, more water often leads to a slightly lower concentration, but not necessarily to lower extraction – the interplay is what counts.

Special features of the French Press (Immersion) vs. Pour-Over

The French press is an immersion brewing method: coffee and water brew completely together, instead of percolating in a filter bed. This changes how the ratio, grind size, and brewing time affect the brewing process.

• Complete immersion means even wetting and heat distribution – good for reproducible results.
• The metal filter allows oils and fine particles to pass through: more solids, less filtration clarity than with paper filters.
• Agitation (stirring) and resting phases influence particle distribution and clarity of the result.

Why particle density and the filter basket determine the result

Only the coarsest particles remain in the metal filter. Fines (the finest particles) can end up in the cup and increase the body – with the risk of a "muddy" taste.

• A consistent, coarse grind reduces fines and makes the cup cleaner.
• A gentle pulling motion (little movement) allows fines to sediment; careful lowering of the plunger preserves clarity.
• “Crust break and skim”: After 3–4 minutes, break the crust and skim off the foam/fines – this results in more balanced, clearer cups.

Recommended ratios according to roast level

The roast level affects solubility. Lighter roasts are denser and dissolve less readily, darker roasts dissolve more quickly. Therefore, adjust the coffee-to-water ratio accordingly when using a French press .

Light: 1:14.5–1:16 for more extraction

Light filter roasts tend to need a little more coffee or a lower ratio so that the sweetness and fruitiness can fully come through.

• Starting ratio: 1:15 (≈ 67 g/L), for very light roasts 1:14.5 (≈ 69 g/L)
• Grind size: medium-coarse rather than very coarse to avoid underextraction
• Brewing time: 4:30–5:00 minutes
• Taste: lively acidity, clear sweetness, structured body

Average: 1:15–1:17 as a balanced standard

Medium filter roasts are the most flexible and work best between 1:15 and 1:17.

• Start: 1:16 (≈ 62–63 g/L)
• Grind size : coarse, consistent
• Brewing time: 4:00–4:30 minutes
• Taste: balanced between body, sweetness and clarity

Darker: 1:16–1:18 for less bitterness

Dark roasts dissolve very quickly. More water (higher ratio) and a slightly shorter brewing time tame bitter notes.

• Starting ratio: 1:17 (≈ 59 g/L), for very dark 1:18 (≈ 56 g/L)
• Grind size : coarse to very coarse
• Brewing time: 3:45–4:15 minutes
• Taste: chocolatey, little bitterness, pleasantly well-rounded

Practical conversion: grams per liter and serving sizes

Think in grams per liter of coffee ; then you can quickly scale up any quantity. Basic values:

• 1:15 → 66.7 g/L
• 1:16 → 62.5 g/L
• 1:17 → 58.8 g/L

Calculation method: Dose (g) = Water volume (ml) / Ratio . Example: 500 ml at 1:16 → 500 / 16 = 31.25 g → 31–32 g.

Examples: 250 ml, 500 ml, 1 L and 1.5 L

• 250 ml at 1:16 → approx. 15–16 g (light: closer to 16 g; dark: closer to 14–15 g)
• 500 ml at 1:16 → approx. 31–32 g
• 1 L at 1:16 → approx. 62-63 g
• 1.5 L at 1:16 → approx. 94-95 g

Tip: Due to expansion and retention, some water remains in the coffee cake after pressing – plan for a small buffer (+5–10%) when aiming for very precise target quantities.

Grind size, brewing time, temperature: the adjustable parameters

Your French press grind size , brewing time , and temperature all work together. Use these settings to fine-tune the ratio , rather than constantly changing them drastically.

• Grind size: coarse to very coarse; uniform particles are more important than "extremely coarse".
• Brewing time: 4:00–5:00 minutes depending on the degree of roasting and ratio.
• Temperature: 92–96 °C; lighter areas preferably hotter, darker areas rather moderate.

Coarser grind, 4:00-5:00 minutes, 92-96°C

1. Preheating: Warm the pot with hot water.
2. Weigh out the dose: e.g. 31 g for 500 ml at a ratio of 1:16.
3. Pour on water: 92–96 °C, completely wet.
4. Stirring: 1–2 gentle turns for even extraction.
5. Let it steep for 4:00–5:00 minutes (adjust to roast level).
6. Crust break and skim: Break up the crust, skim off foam/fines.
7. Press: Press slowly, without pressure, until just above the coffee grounds.
8. Serving: Transfer immediately or pour directly to avoid any further settling.

If the cup seems dull despite the correct ratio , check the grind size (more even!), agitation (less) and calmness (let it sediment for longer).

Bean selection: Which coffees are suitable for the French press ?

The French press is ideal for aromatic, clean filter roasts with a medium to light roast profile. The oils and fine particles accentuate sweetness and texture – perfect for chocolatey-nutty profiles, but also for fruity, floral coffees, provided the ratio and technique are right.

• Light roasts : more aroma potential, require precise ratios and slightly hotter water.
• Medium roasts: very versatile, a "no-brainer" for everyday use and for guests.
• Very dark roasts: can quickly become bitter in a French press – increase the ratio and brew for a shorter time.

Sensory tips depending on origin and roasting profile

• Ethiopia (washed): floral, citrus notes; 1:15.5–1:16.5, hotter temperature.
• Ethiopia (natural): red fruits, full mouthfeel; 1:16 for balance, stir gently.
• Kenya: juicy berries, high acidity; 1:16–1:17 for clarity and structure.
• Central/South America (e.g. Colombia, Guatemala): cocoa-nutty; 1:15.5–1:16 as standard.
• Brazil: soft, sweet; 1:16–1:17 for clear, chocolatey cups.
• Indonesia: spicy, earthy; 1:16–1:17 to tame bitter notes.

Common errors and quick fixes

Error patterns can usually be corrected with minor ratio adjustments and technical checks.

Too bitter, too thin, muddy – here's how to correct the ratio

• Too bitter/astringent:
  • Increase the ratio (e.g., 1:16 → 1:17)
  • Coarser grind, shorter brewing time
  • Lower the temperature (e.g., from 94 to 92 °C)
• Too thin/watery:
  • Lower ratio (e.g. 1:16 → 1:15.5)
  • Grind slightly finer, extend brewing time
  • Stirring harder is no substitute – a clean grind is crucial.
• Muddy/murky:
  • Grind size more consistent and tends to be coarser
  • After 3-4 minutes, break the crust and skim off the foam/fines.
  • Slowly guide the stamp, immediately transfer the contents from the cup.
• Flat/boring:
  • Choose a lighter roast or slightly reduce the ratio (more coffee).
  • Brew at a higher temperature (up to 96 °C), gentle agitation

Mini coffee calculator (formula) for consistent results

With a simple formula, you can pinpoint your target quantity based on the ratio – perfect for coffee calculator conversions on the go.

Step-by-step: Target quantity, ratio , dose

1. Determine your target amount of water (ml): e.g. 750 ml.
2. Choose the ratio to match the roast level: e.g. 1:16 for medium.
3. Calculate: Dose (g) = Water volume (ml) / Ratio → 750 / 16 = 46.9 g → round to 47 g.
4. Fine-tuning:
   • Underextraction (sour/thin) → grind slightly finer or use 2–3 g more coffee or brew for 15–30 s longer.
   • Over-extraction (bitter/harsh) → use a slightly coarser grind or 2-3 g less coffee, or brew for 15-30 seconds less.
5. Ensuring consistency:
   • Use a scale and a timer.
   • Record bean type, roast level, ratio, grind size , time and temperature.

Practical tip: If you want to control the actual cup size instead of the amount of water, keep in mind that liquid will remain in the coffee grounds. A rough guideline is 1.8–2.2 g of retention per gram of coffee.

Next up: Test one or two ratios with your favorite beans, note the grind size , time, and temperature, and adjust in small increments. Once you've found your sweet spot, scale it to any serving size using the gram-per-liter approach—this will turn your French press ratio into a reliable recipe, whether it's a 250ml solo cup or 1.5L for brunch. #staywild