Instructions

1. Determine what kind of coffee you are working with. Different kinds of coffee have different amounts of caffeine. Instant coffee, on average, has 32.5 milligrams of caffeine per gram of dry grounds, while ground coffee has 13.5 milligrams per gram. Decaffeinated coffee still has some caffeine, measuring in about 0.6 milligrams per gram of grounds.

2. Measure the amount of pulp. If your grounds are already wet, you have coffee pulp. Figure out how much you have by weighing it on a scale; it will help if you keep the pulp in the filter so that it does not spread and create a mess.

3. Convert the pulp into dry measurements. Do this by subtracting the amount of water you added. You can find this amount by calculating exactly how much coffee you initially put into the coffee maker, minus the amount of coffee that was produced. This amount will be very small, but it will affect the mass of the final pulp. Measure out an equivalent amount of water (which is usually measured by volume rather than weight) and weight it on your scale, being sure to subtract the weight of the container from your final measurement. Subtract the weight of the water from the weight of the pulp.

4. Multiply the dry measurement by the amount of caffeine in that type of coffee. If you made ground coffee and have 2 grams of dry grounds, for instance, you will multiply this by 13.5 for a final answer of 27 milligrams of caffeine in the coffee pulp.