Definition
Brew ratio is the relationship between the mass of coffee grounds and the mass of water used to brew. It directly controls the strength (TDS) of your final beverage.1 This relationship is linear and predictable: doubling coffee dose at constant water volume doubles TDS, while doubling water at constant dose halves TDS.
More water relative to coffee = weaker, lighter-bodied cup. Less water = stronger, more concentrated cup. Ratio is independent of extraction percentage—you can have high extraction with any ratio, and any TDS with any extraction level.2
Key Insight
Brew ratio controls strength. Grind size controls extraction. These are independent variables.
Ratio Formats
Ratios are expressed in multiple formats. They all describe the same relationship:3
Common Formats:
1:15 ratio
1 part coffee to 15 parts water. Example: 20g coffee + 300g water. Most common in specialty coffee.
60g/L
60 grams of coffee per liter of water. Equivalent to 1:16.67 ratio. Common in commercial settings and historical literature.
Percentage (6.25%)
Coffee as percentage of total weight. 6.25% = 1:15 ratio. Used in some scientific papers and brewing software.
Most specialty coffee uses the 1:X format because it is intuitive and scales easily. A 1:15 ratio works the same whether you are brewing 20g or 200g. The ratio remains constant; only absolute quantities change.
Common Ratios and What They Produce
1:13 - 1:14 (Strong)
TDS: ~1.50-1.60%
Very concentrated. Intense flavor. Common for small batches or when you want maximum impact. Can feel heavy if over-extracted. Used in some competition recipes for high-clarity coffees where concentration compensates for delicate flavor intensity.4
1:15 - 1:16 (Balanced)
TDS: ~1.30-1.45%
The most common pour-over ratio. Balanced strength and clarity. Good starting point for dialing in new coffees. Works for most roast levels. This range produces TDS values within the SCA Golden Cup standard when paired with 18-22% extraction.5
1:17 - 1:18 (Light)
TDS: ~1.15-1.25%
Lighter body, higher clarity. Good for delicate coffees where you want transparency over intensity. Can taste watery if extraction is low. Scandinavian filter coffee traditions often use ratios in this range, prioritizing clarity and tea-like mouthfeel.6
These ranges assume well-extracted coffee (18-22% extraction). If extraction is low, even a strong ratio will taste weak because you have not dissolved enough material. The relationship is multiplicative: TDS = (dose ÷ water) × extraction%.
Making Adjustments
Adjusting ratio is simple: use more or less water while keeping coffee dose constant. Or use more or less coffee while keeping water constant.7 The choice depends on your brewing vessel capacity and desired final volume.
When to Adjust Ratio:
- •Coffee tastes weak but balanced: Reduce water (stronger ratio like 1:14). Extraction is good, you just need more concentration.
- •Coffee tastes too strong/intense: Add more water (lighter ratio like 1:17). This will not fix extraction problems, only intensity.
- •Coffee tastes both sour and weak: Do not add more coffee. Grind finer instead. You have low extraction and low strength. Adding coffee makes it strong but still sour.
Pro tip: Once you find an ideal ratio for a coffee, stick with it and adjust other variables (grind, temperature) for flavor. Constantly changing ratio makes it harder to build consistency. World Barista Champions often use the same ratio across multiple coffees, varying only extraction variables.
References & Notes
- 1.
The relationship between brew ratio and TDS is mathematically straightforward: TDS (%) = (coffee_mass × extraction_yield) ÷ water_mass. This linear relationship means that TDS scales proportionally with ratio when extraction is held constant. For example, at 20% extraction: a 1:15 ratio yields 1.33% TDS, 1:16 yields 1.25% TDS, 1:17 yields 1.18% TDS. Each ratio increment of 1 changes TDS by approximately 0.07-0.08% at typical extraction levels. This predictable relationship allows precise strength control independent of extraction optimization, forming the basis of the Coffee Brewing Control Chart's two-dimensional framework.
- 2.
The orthogonality of brew ratio and extraction percentage is fundamental to brewing control. Ratio determines how much extracted material gets diluted, while extraction determines how much material gets extracted in the first place. These variables are controlled by different mechanisms: ratio is set by dose and water quantity (before brewing begins), while extraction is controlled by grind size, temperature, time, and agitation (during brewing). This independence means you can dial in extraction first (optimizing flavor balance), then adjust ratio to achieve desired strength, without re-optimizing extraction. Professional brewing workflows exploit this separation: cup at multiple ratios with the same grind to find strength preference, then dial grind to optimize extraction at that ratio.
- 3.
Different ratio notations arose from different contexts. The 1:X format (1:15) comes from manual pour-over culture, emphasizing the intuitive "parts" relationship and easy mental scaling. The g/L format (60g/L) comes from commercial batch brewing where recipes scale to large volumes—it's easier to calculate 60g per liter than convert 1:16.67 when brewing 10 liters. The percentage format (6.25%) appears in scientific literature and brewing software, useful for mass balance calculations. All three are interconvertible: 1:X = (1000÷X) g/L = (100÷(X+1))%. For reference: 1:15 = 66.7 g/L = 6.25%, 1:16 = 62.5 g/L = 5.88%, 1:17 = 58.8 g/L = 5.56%.
- 4.
Strong ratios (1:13-1:14) are less common in general practice but appear strategically in competition and specialty contexts. World Brewers Cup 2019 winner Emi Fukahori used 1:13.3 for a delicate Ethiopian natural, creating high concentration (1.52% TDS) to amplify subtle fruited notes. The stronger ratio compensated for the coffee's light body, creating perceived richness without over-extraction. However, strong ratios are unforgiving: any extraction defects become more concentrated and noticeable. They also reduce margin for error—an overextracted brew at 1:13 tastes significantly worse than the same overextraction at 1:16 due to higher concentration of bitter compounds. Use strong ratios only when coffee quality and brewing precision are high.
- 5.
The 1:15-1:16 range represents the intersection of historical standards and modern practice. The SCA Golden Cup standard (developed from Lockhart's 1950s MIT research) recommends 55±5 g/L (1:15.7-1:19.4), centered around 1:18. However, modern specialty coffee trends stronger. Analysis of World Brewers Cup recipes (2015-2024) shows modal ratio of 1:15.8, with 72% falling between 1:15-1:17. This shift reflects higher coffee quality (more flavor intensity per gram) and preference for concentration over dilution. Competition coffee averages 1.38% TDS versus the SCA standard of 1.25% TDS, indicating specialty coffee's evolution toward stronger brewing norms while maintaining similar extraction levels.
- 6.
Light ratios (1:17-1:18) prioritize clarity and delicacy over intensity. Scandinavian coffee culture, particularly in Norway and Sweden, traditionally brews at 1:18-1:20, producing TDS values of 1.0-1.2%. This creates tea-like mouthfeel and emphasizes high notes (acidity, florals) while minimizing body and bitterness. The lighter ratio works synergistically with Scandinavian roasting styles (lighter roasts, higher acidity) and water profiles (low mineral content). However, these ratios are unforgiving of underextraction—at 16% extraction and 1:18 ratio, TDS is only 0.89%, tasting distinctly weak to palates accustomed to 1:15-1:16 brewing. Light ratios require excellent extraction technique to avoid hollow, thin flavors.
- 7.
Ratio adjustment methodology depends on desired outcome and practical constraints. To increase strength while maintaining volume, increase dose proportionally (e.g., 20g→22g at 300g water changes 1:15→1:13.6). To increase strength while maintaining dose, reduce water proportionally (300g→270g changes 1:15→1:13.5). These produce identical strength but different volumes. In practice, dose-constant adjustment is preferred for single-serve brewing (easier to measure smaller water quantity precisely), while water-constant adjustment suits batch brewing (easier to maintain fixed output volume). Small adjustments (±1 ratio increment) require ±6-7% water change or dose change—for a 20g dose at 1:15, moving to 1:16 means adding 20g water (300g→320g), while moving to 1:14 means removing 20g water (300g→280g).