Coffee extraction occurs when hot water is poured over coffee grounds, causing desirable compounds such as caffeine, carbohydrates, lipids, melanoidins and acids to be extracted from the grounds. The degree to which extraction occurs depends on a number of factors, such as water temperature, brewing time, grind fineness, and quantity of grounds.

Brew ratio describes the ratio of coffee to water, by mass.

Strength, also known as solubles concentration, refers to the percentage of dissolved solids per unit of liquid in the final beverage. A higher concentration of solubles is associated with a stronger beverage, and lower concentration with a weaker, more "watery", beverage. Strength varies between coffee beverage types; for most it ranges from 1.15% and 1.35%. Ristretto, one of the strongest traditional coffee drinks, can contain up to 0.75 g of solubles per 15 gram serving (over 5% of total volume), making it more than four times as strong as the typical coffee beverage. Strength can also vary to a significant degree between coffee grown in different regions.

As the degree of extraction increases, strength increases, resulting in a beverage that is darker in color and oilier in terms of mouthfeel – however, this can also vary by amount of suspended solids (very small grinds, so-called "fines"), particularly in French press brewing. As extraction time increases, the risk of unwanted solubles – often associated with overwhelming bitterness – being extracted also increases. If yield is held constant, strength is determined primarily by brewing ratio. Caffeine is extracted early in the brewing process, so longer extraction does not result in significantly more caffeinated coffee. Adding water to a drink after brewing changes strength but not yield (yield is determined by the amount of water initially present during brewing). An Americano only differs from an espresso in strength – it is traditionally diluted after brewing to a strength below 1.5% (also resulting in the removal of crema).

Extraction yield refers to the solubles dissolved during brewing. This is often expressed as a percentage of the coffee's mass. It is also known as solubles yield or simply extraction. The extraction yield percentage describes the mass transferred from coffee grounds to water, expressed as a percentage of the initial mass of the grounds. It is given by the following:$${\displaystyle Y={\frac {M_{2}\cdot t}{M_{1}}}}$$where ${\displaystyle Y}$ is the extraction yield expressed as a percentage, ${\displaystyle t}$ is the total dissolved solids expressed as a percentage of the final beverage, ${\displaystyle M_{1}}$ is the mass of the grounds in grams, and ${\displaystyle M_{2}}$ is the final beverage's mass in grams. This means that an extraction yield of 20% can be obtained by brewing 18 grams of coffee, resulting a 36-gram final beverage with a ${\displaystyle t}$ of 10%. Yield can also be expressed as total dissolved solids, or parts-per-million (ppm).

An extraction yield of 18% to 22% is desirable for most traditional coffee beverages. Yields of under 18% are considered under-extracted, or under-developed – desirable compounds have not been extracted to the fullest. The resulting beverage is unbalanced and often associated with a predominantly sour taste – acids are extracted early in the brewing process, while balancing compounds such as sugars and bitter substances are extracted later. Yields of over 22% are considered over-extracted and are often associated with a predominant bitterness – bitter compounds are extracted after acids and sugars have largely dissolved. However, in certain situations where advanced brewing equipment is involved, yields surpassing 22% can be achieved absent the characteristic bitterness.

A brewing control chart can be used to control a beverage's degree of extraction and strength. The optimal ratio between extraction and strength is represented by a rectangle in the center of the chart – within that area, coffee is neither over- nor under-extracted, and neither too strong nor weak. At any point along the diagonal line plotted on the chart, extraction and strength are directly proportional.

The following describes the relationship between strength and brew ratio.$${\displaystyle {\frac {t}{V}}={\frac {M}{V}}\times {\frac {t}{M}}}$$where ${\displaystyle t}$ is the total dissolved solids expressed as a percentage of the mass of the grounds, ${\displaystyle V}$ is the volume of the water used, and ${\displaystyle M}$ is the mass of the grounds. In other words, the strength of a beverage is the product of the brew ratio and the extraction percentage.