How Much Caffeine in Used Coffee Grounds

Caffeine is a stimulant that is found in coffee, tea, chocolate, and soda. It stimulates the central nervous system and increases alertness. The caffeine content of coffee grounds varies depending on how much coffee is used, the length of brewing time, and the type of beans.

Coffee grounds have been used for a long time to provide health benefits. Learning how much caffeine is in used coffee grounds can help you make the most out of these benefits.

How Much Caffeine Is in Used Coffee Grounds?

The caffeine in used grounds can be between 3.59 and 8.09 milligrams per gram. The caffeine content in used grounds is measured using a caffeine extraction method. This method measures how much caffeine is present in a sample of used grounds.

A coffee grounds in a small brown wooden box under coffee beans placed on a round stainless plate

However, much like the coffee itself, the caffeine content of grounds changes over time. The caffeine content of used grounds depends on how long they have been in contact with the coffee itself, the bean used, the roast level, and how the grounds were processed.

Caffeine in Coffee Beans

During roasting, coffee beans are extracted from their caffeine. The process involves heating the coffee bean at a high temperature to bring out its flavor and aroma, which results in a powdery substance called coffee grounds.

Coffee grounds are about 40 to 60 percent caffeine (depending on how the beans are roasted.). The rest of the coffee bean has been roasted away and removed during processing.

The amount of caffeine in coffee beans depends on several factors, including:

  • Roasting time
  • The fineness or coarseness of the grind
  • Roasting temperature
  •  The amount of moisture present during processing

How Long Does Caffeine in Coffee Last?

In ideal conditions, the caffeine in coffee usually outlasts the flavors and oils of coffee grounds. For most roasted coffees, that’s at least four years.

The used or spent grounds of coffee contain a surprising amount of caffeine. The caffeine extraction happens at the very end of the brewing process. In fact, caffeine is partially responsible for the bitter taste of coffee after brewing it for a long time.

Is It Possible to Make Cold Brew From Yesterday’s Coffee Grounds?

Yes, yesterday’s grounds can work for the cold brew method. This method does not use any additional grounds when brewing your cold brew coffee.

You want to eliminate any type of liquid in your brewing process completely. So, you will need to find a way to infuse the flavor of coffee into your cold brew and then let it sit on the countertop or in the fridge until you are ready to enjoy it.

The most common way people do this is by using a French press or another method involving little or no added water. This works because the ground coffee actually creates more surface area for your brewing process. This allows more grounds to be exposed to air and better flavor extraction.

How Can You Lengthen the Life of Used Coffee Grounds?

Recycling coffee grounds is a great way to eliminate coffee filters and other coffee waste. They can be used as compost if you have the space, and they make a great addition to your garden.

If you have more than enough leftover grounds after making one pot of coffee, go on ahead and lengthen their life:

A close-up of coffee grounds on a plastic container with a white plastic scoop on top

Store in an Airtight Container

To ensure that your grounds stay fresh, keep them in an airtight container. This will keep oxygen and moisture out, so they’ll stay fresher longer. Moisture can also cause mold and mildew, which will ruin your entire supply of old grounds in just a matter of time.

Also, don’t store them in direct sunlight or under fluorescent lights. Used grounds can absorb heat and light quickly when they’re exposed to either one too much.


Freezing is your best option if you need to store your grounds for over three months. This method will ensure that they retain their freshness and flavor while being stored in bulk quantities.

Freezing coffee grounds is pretty easy:

  • Freeze the ground coffee in ice cube trays or airtight containers.
  • Pour each serving into an airtight container and
  • Store them in your freezer until you are ready to use them again later on down the line.

Related Questions

Can You Use Coffee Grounds a Second Time?

Using grounds to brew a cup of coffee a second time is not recommended. Reusing the grounds will result in a bitter, over-extracted mess, while letting them dry first will result in a sour, disappointing cup.

Is Eating Coffee Grounds Okay?

Yes, eating coffee beans and grounds is okay. Consuming coffee grounds can give you an energy boost. Grounds are a natural source of caffeine and can be used to add some extra boost to your morning cup.


So, the best way to answer how much caffeine is in used coffee grounds is this: The caffeine content varies between 3.59 and 8.09 milligrams per gram (mg/g). This amount depends on the bean used, the roast level, and how the grounds were processed.