Filter Coffee
Ratio Calculator
Exact amounts for Western drip and cone filter coffee, and complete South Indian filter coffee recipes with decoction strength, chicory percentage, and milk ratio calculations.
Filter Coffee Calculator
5 steps to your exact recipe
Filter Coffee Ratio Quick Reference
Western: amounts per 6-oz machine cup. Indian: amounts per 150ml tumbler (decoction only; mix 1:3 with milk).
| Style | Strength | Coffee per Serving | Water per Serving | Ratio | Caffeine |
|---|---|---|---|---|---|
| Western | Light | 5.5g (1 tbsp) | 100ml / 3.4 fl oz | 1:18 | ~75mg |
| Western | Standard | 6.2g (1.1 tbsp) | 100ml / 3.4 fl oz | 1:16 | ~85mg |
| Western | Strong | 7.7g (1.4 tbsp) | 100ml / 3.4 fl oz | 1:13 | ~105mg |
| Indian | Light | 10g per tumbler | 50ml (decoction) | 1:5 | ~120mg |
| Indian | Regular | 12g per tumbler | 48ml (decoction) | 1:4 | ~140mg |
| Indian | Strong | 15g per tumbler | 45ml (decoction) | 1:3 | ~160mg |
What Is the Right Coffee to Water Ratio for Filter Coffee?
The Specialty Coffee Association of America sets the Golden Cup standard at 55 grams of coffee per liter of water (a ratio of approximately 1:18), which they identify as the extraction sweet spot for filter coffee brewed at 93 to 96 C. In practice, most people find this slightly light, and the most common home ratio of 1:16 (about 62 grams per liter) gives a more balanced, full-bodied result.
The challenge with filter coffee ratios is the inconsistency in how “cups” are measured. Most home drip machines label their carafes in 5-ounce or 6-ounce increments rather than the 8-ounce cups most people drink from. A 12-cup filter machine holds 72 ounces of water (about 2.1 liters), not 96 ounces. The calculator above uses 6 ounces per machine cup as the standard because that is the most common convention. If your machine uses 5-ounce cups, your actual water volume is slightly less than the calculator shows.
Why your filter machine temperature matters more than your ratio
The most overlooked variable in filter coffee is water temperature. SCAA certification requires machines to brew between 92 and 96 C. Most budget drip machines only reach 85 to 88 C. At this temperature, extraction is significantly incomplete regardless of the coffee dose. The coffee tastes flat, slightly sour, and one-dimensional. The most impactful upgrade for filter coffee is not a better ratio or better coffee — it is a machine that actually reaches the correct temperature. Specialty batch brewers like the Breville Precision Brewer, Technivorm Moccamaster, and OXO Brew are designed specifically to hit this range.
What Is South Indian Filter Coffee and How Does the Ratio Work?
South Indian filter coffee, called kaapi or kapi across Tamil Nadu, Karnataka, and Kerala, is not just a brew method — it is a deeply embedded cultural ritual with specific equipment, specific ratios, and specific serving customs that vary by household. The term “filter coffee” in South India always refers to this tradition, not to drip machines.
The coffee is brewed in a two-part stainless steel device. Ground coffee (often blended with chicory) is packed into the upper chamber, which has a perforated base. Hot water is poured over the grounds and drips very slowly through into the lower collection chamber over 15 to 30 minutes. The result is a decoction: a dark, syrupy, extremely concentrated extract that is not meant to be drunk straight. The decoction is mixed with hot, often boiled and frothy whole milk in a ratio of approximately 1 part decoction to 3 parts milk, then poured back and forth between a dabarah (wide-mouthed metal bowl) and a tall metal tumbler to aerate and cool it to drinking temperature.
Why the decoction-to-milk ratio is a defining choice
The 1:3 decoction-to-milk ratio is the standard, but experienced filter coffee drinkers calibrate this to their taste and to the strength of their decoction. A stronger 1:3 decoction (made with 15 grams of coffee at a 1:3 coffee-to-water ratio) produces a cup with more coffee intensity when mixed at 1:3 with milk. A weaker decoction mixed at 1:2 with milk might produce the same final intensity. The calculator handles this by keeping the milk ratio at 1:3 (per tumbler) and letting the decoction strength be the variable, which is how most South Indian homes actually calibrate the drink.
What Does Chicory Do in South Indian Filter Coffee?
Chicory root, roasted and ground, has been added to filter coffee in South India for generations. The reasons are partly economic (chicory was cheaper than coffee during periods of rationing and scarcity) and partly flavor-driven: chicory adds a distinctly bitter, slightly sweet, woody character that has become inseparable from the traditional South Indian filter coffee taste profile.
Chicory does not contain caffeine. It does change the extraction characteristics of the decoction: chicory is more soluble in water than coffee and extracts differently during the slow drip, adding body and color to the decoction in ways that straight coffee alone does not produce. The thicker, darker decoction that chicory produces mixes with milk differently than a pure-coffee decoction — it tends to produce the characteristic dark contrast layer at the bottom of the tumbler before mixing.
Which chicory percentage is right for you
Most commercial South Indian coffee blends contain 20 to 30 percent chicory. If you are buying a labeled brand like MTR, Cothas, or Narasu, the chicory percentage is printed on the tin and the blend is already done for you. If you are blending your own from separate roasted coffee and roasted chicory, starting at 20 percent chicory is the most approachable entry point. Moving to 30 percent gives a noticeably more traditional result. Beyond 40 percent, the chicory character can overwhelm the coffee.
What Grind Size to Use for Filter Coffee
Western filter coffee: medium grind for flat-bottom basket filters and most drip machines, similar in texture to coarse table salt. Medium-fine for cone filters and specialty batch brewers, which have slightly longer water contact time and extract more efficiently from a finer particle. Too coarse and you get weak, under-extracted coffee; too fine and the filter may slow or clog, producing bitter over-extraction.
South Indian filter coffee: fine-to-medium fine grind, finer than drip coffee but not as fine as espresso. The packed, pressed grounds in the traditional filter device create enough resistance for the slow 15 to 30 minute drip without an extremely fine grind. If using a pre-ground South Indian coffee brand, it is already calibrated correctly. If grinding your own, aim for a grind slightly finer than what you would use in a pour over V60, pressed firmly into the filter upper chamber.
Filter Coffee Troubleshooting
Frequently Asked Questions About Filter Coffee
What is the filter coffee ratio?
+For Western drip/cone filter coffee: 1:16 to 1:18 (1 gram per 16 to 18 ml water). The SCAA Golden Cup standard is 1:18. For South Indian filter coffee: the decoction is brewed at 1:3 to 1:5, then mixed 1:3 with hot milk. Use the calculator above to get exact amounts for your batch size and strength preference.
How much coffee do I use per cup in a filter machine?
+About 6 grams per 6-oz machine cup at the standard 1:16 ratio. For a full 12-cup carafe (approximately 72 oz / 2.1 liters of water), use 73 grams of ground coffee. In tablespoon terms, that is just over 13 level tablespoons. For a lighter result, reduce to 60 grams total.
What is South Indian filter coffee and how is it different?
+South Indian filter coffee is brewed in a two-part stainless steel device that produces a concentrated decoction, then mixed with hot whole milk at 1:3. It uses a finer grind, much higher coffee dose, often includes chicory, and takes 15 to 30 minutes to brew the decoction. It is a completely different preparation from Western drip filter coffee.
What is the South Indian filter coffee decoction to milk ratio?
+Standard: 1 part decoction to 3 parts milk. For a 150ml tumbler, that is approximately 37ml decoction and 113ml hot milk. For a stronger result, use 1:2 (50ml decoction, 100ml milk). For a milder cup, 1:4 (30ml decoction, 120ml milk).
What does chicory do in filter coffee?
+Chicory root, when roasted and ground, adds a bitter, slightly caramel-sweet, woody flavor to the decoction. It increases body and creates the thick, dark character of traditional South Indian filter coffee. It contains no caffeine. South Indian coffee blends typically contain 20 to 40 percent chicory.
What is the best coffee to water ratio for a 12-cup filter machine?
+At 1:16: about 73 grams for a 12-cup carafe (approximately 1.17 liters). At 1:18: about 65 grams. Most 12-cup machines hold 72 ounces total, not 96, because they measure in 6-ounce cups. Always verify your actual machine capacity before scaling the recipe.
Can I make filter coffee without a machine?
+Yes. A Melitta-style cone filter with paper filters sits on any cup or carafe. Use the same ratio as a drip machine. For South Indian filter coffee, the traditional stainless steel device is the only practical manual option since it provides the slow, controlled drip that produces the correct decoction.
What grind size is best for filter coffee?
+Western filter: medium grind (like coarse table salt) for drip machines and flat-bottom baskets. Medium-fine for cone filters and specialty batch brewers. South Indian filter: fine-to-medium fine, finer than drip but not as fine as espresso. Pre-ground South Indian coffee brands are already calibrated correctly.
Why does my filter coffee taste weak?
+Most likely cause: water temperature too low. Most budget drip machines only reach 85 to 88 C, not the 92 to 96 C that SCAA requires. The coffee extracts incompletely and tastes flat. Upgrade to a temperature-controlled machine or use a manual cone filter with a kettle where you control the water temperature.
How much coffee do I need for South Indian filter coffee?
+For one tumbler at the standard regular strength: 12 grams of coffee (or coffee-chicory blend) with 48ml of boiling water. This produces about 38 to 40ml of decoction, which is then mixed with 110ml of hot milk. For four tumblers, use 48 grams of blend with 192ml of boiling water.
Three Things That Improve Filter Coffee Every Time
For Western filter coffee: pre-heat everything
Run a brew cycle of plain hot water through your drip machine and carafe before adding coffee. This brings the internal components up to temperature and reduces the heat loss that occurs when cold metal contacts the first pours of hot water. The difference in cup temperature and extraction quality between a preheated machine and a cold one is measurable. For manual cone filter brewing, preheat the cone, the paper filter, and the carafe or mug with hot water before adding coffee.
For South Indian filter coffee: the quality of the milk matters
South Indian filter coffee traditionally uses whole, full-fat milk, often brought to near-boiling before mixing with the decoction. The fat content of the milk affects the texture and mouthfeel of the final cup significantly. Skim milk or reduced-fat milk produces a thin, watery result that cannot replicate the traditional experience. The milk is sometimes boiled with a small piece of whole cardamom for a subtler aromatic note in some households.
Use filtered water for both styles
Hard water with high mineral content can leave deposits in drip machines, clog the South Indian filter device’s perforated plates, and add an aftertaste that competes with the coffee. Chlorinated tap water reacts with coffee compounds and produces off-flavors that are especially noticeable in lighter filter coffee where the base flavor is more transparent. A simple carbon filter pitcher improves filter coffee quality noticeably in most urban water supplies.
Your Starting Point for Filter Coffee
For Western filter coffee: 1:16 ratio, 92 to 96 C, medium grind, brewed immediately and poured into a thermal carafe. For South Indian filter coffee: 12 grams of coffee or coffee-chicory blend per tumbler, 48ml of boiling water, 15 to 30 minutes to drip, then mixed 1:3 with hot whole milk and poured between dabarah and tumbler before serving. Both methods produce their best results when the water temperature is correct and the coffee is fresh. Everything else is calibration from those two foundations.