What is the 30 second rule for espresso?
The 30-second extraction rule suggests that a well-balanced espresso shot should take approximately 25-30 seconds to extract when using 18-20 grams of ground coffee and yielding about 30-40 milliliters of espresso. Regarding fluid ounces alone, it would take about eight espresso shots to fill a coffee cup. However, we strongly advise against drinking that much espresso. The per-ounce caffeine concentration of espresso (63 mg) is far higher than drip coffee (about 12 mg per fluid ounce).The ideal level of bar passing through your coffee grounds should be around 7-11 bars of pressure, though some espresso machines will be able to hit higher bar. Machines capable of hitting 9 bars of pressure will have the ability to produce a rich and concentrated espresso shot.