Reference · coffee acidity

Is coffee acidic? pH by brew method and roast

Yes, mildly: brewed coffee measured between pH 4.80 and 5.92 in the lab studies on this page, on a scale where 7 is neutral, and roast level moved that number more than brewing hot or cold did. How sour a cup tastes is a separate question, and it follows a different measurement.

Updated 2026-11-13 · sources listed at the end · a summary of published measurements, not medical advice

Coffee pH chart: measured pH by brew method and roast

Compare rows within one study: coffees, water and roasts differed between labs. In the Swiss study, filter coffee was the most acidic brew after the capsule espresso, the moka pot sat next to the French press at the least acidic end, and the espressos and lungos fell in between.

pH, titratable acidity and the acidity you taste

• pH measures how acidic the liquid is right now. The scale is logarithmic: “a difference of one in pH is equivalent to a tenfold difference in hydrogen ion concentration” (Wikipedia).
• Titratable acidity measures how much acid there is in total: the volume of base needed to bring a sample to a set pH. The UC Davis team titrates 50 ml of coffee to pH 8.2; Rao and colleagues titrate 40 ml to 6.5. Gloess and colleagues use 6.6, roughly the pH in the mouth while drinking, and 8.0 to capture weaker organic acids.
• Taste acidity is what a panel calls sour or bright. In the UC Davis drip studies, titratable acidity “strongly” correlated with perceived sourness, while pH showed no relationship in the temperature experiment and only a weak one across roasts. Gloess and colleagues found “neither a correlation of the pH value nor of the titratable acidity with the sensory aspect of acidity.”

Rao and Fuller call pH “a poor measurement for the complex acid chemistry” of coffee; in their hot brews the two measures barely correlated (r = −0.15). Across roasts, both move together:

TA is ml of 0.1 N sodium hydroxide per 40 ml of coffee to reach pH 6.5 (Rao, Fuller & Grim 2020). Every cold brew in both Rao studies had lower titratable acidity than its hot counterpart. In UC Davis consumer tests, about half preferred more acidity and half less.

The acids in coffee

• Chlorogenic acids. Esters of caffeic acid and quinic acid (Wikipedia). In Rao and Fuller’s hot brews, total chlorogenic acids ran from 2,503 to 3,270 mg/L, with 5-CQA the most abundant form. The UC Davis review of 129 publications reports that they fall as roasting proceeds.
• Citric and malic acids. The most abundant acids in green coffee; they break down into other acids during roasting (Yeager et al.). Citric and acetic acid “contribute strongly to the sourness” of a brew (Batali et al.).
• Quinic acid. “More bitter than sour” (Batali et al.); 5-CQA is “less sour than free quinic acid” (Yeager et al.).
• Acetic and formic acids. Acetic acid rises in roasting as sucrose breaks down; formic acid increases in robusta (Yeager et al.).

What changes coffee’s acidity when you brew

1. Roast level, most of all. UC Davis found roast “a much bigger driver of difference in pH than brewing.” From lightest to darkest roast, Rao’s hot brews went from pH 4.80 to 5.39 and titratable acidity fell by more than half. Roast names are explained on coffee roast levels.
2. Strength. Titratable acidity “showed a clear linear correlation to TDS,” and sourness “increases strongly with TDS.” Strength is measured with a TDS refractometer.
3. Extraction. Sourness “decreases with PE” (extraction yield), while titratable acidity showed no relationship with it. The most sour cups were high TDS, low extraction “regardless of roast or brewing temperature”; the brewing control chart maps both axes.
4. Hot or cold water. At matched 2% TDS, cold brews were 0.1–0.2 pH units higher than chilled hot brews (Ristenpart). In Rao’s roast study the cold brews read 0.20–0.36 higher (our arithmetic from the table). Details and steep times are in the cold brew guide.
5. Hot brew temperature. UC Davis found “no difference in pH based on brew temperature”; see water temperature.
6. Brewing water. Perceived acidity “corresponds to the amount of acids extracted from the coffee minus” what the water’s alkalinity neutralizes, and alkalinity’s effect is “several hundredfold times higher than that of pH” (Wellinger). The DIY coffee water page sets alkalinity targets.
7. Method. Nine methods with one Guatemalan coffee spanned only pH 5.51–5.92 (Gloess et al.).

If a cup tastes sharply sour, the taste troubleshooting chart lists which variable to change first.

Is coffee a low-acid food?

In US food-safety rules, yes. NC State Extension defines low-acid foods as those with “a final pH that is greater than 4.6” (with water activity above 0.85), and every measurement above is higher. The label governs how packaged food is processed, not taste or digestion.

Coffee, reflux and other health questions

This page does not give health advice. The NIH’s National Institute of Diabetes and Digestive and Kidney Diseases lists “coffee and other sources of caffeine” and “acidic foods, such as citrus fruits and tomatoes” among foods and drinks “commonly linked to GERD symptoms,” and says: “Talk with your doctor about your diet and foods or drinks that seem to increase your symptoms.” Read the NIDDK guidance on diet for GER and GERD and follow your doctor. Rao and Fuller measured chemistry only and write that “additional research is needed” on health effects of cold brew.

Where the sources disagree

• Hot vs cold. Rao and Fuller (2018) call their hot and cold brew pH “comparable”; Ristenpart and the 2020 roast study found cold brews consistently higher. Both Rao studies found more titratable acid in hot brews.
• Roast and single acids. Overall acidity falls with roast in every study here, but the UC Davis review found no general correlation between roast level and specific organic acids; in arabica they were lowest at medium roast.

Limits: each study used a handful of coffees and its own water and meters, so treat the numbers as ranges, not a forecast for your cup.