How Long Can Coffee Sit Out?

How Long Can Coffee Sit Out

Do you always have leftover coffee in your cup? Ever wonder if it is still safe to drink it after a few hours? Coffee tastes best when it’s hot and freshly brewed but if it has gone cold and sitting out in your cup for a while it could have bad effects. In this article, let us try to find out how long coffee can sit out and helpful information on its proper consumption.

How long can coffee sit out?

Coffee can sit out and last for more or less 30 minutes and its flavor will not be compromised. However, make sure that it is at room temperature which is around 20 degrees Centigrade or 50 degrees Fahrenheit. If it sits out for a couple of hours, coffee begins to develop off-flavors and bitter taste. It will also start to lose its aromatic compounds. 

If you are a black coffee fan, consider yourself lucky. Plain black coffee can sit out at room temperature for more than a day after it is brewed. It is still considered safe to drink during such times but you won’t be able to enjoy its original flavor. Do not reheat black coffee, opt for a thermal mug

Brewed black coffee can last for a week if stored properly inside the refrigerator with temperatures below 40 degrees Fahrenheit while cold brew can last for up to 14 days. An opaque airtight container is a good storage unit for brewed coffee. 

Hot coffee with milk or creamer, almond milk coffee, latte, and cappuccino should only sit out for one to two hours. Beyond that time, you should throw it out already as it is not fit for consumption already.

What happens if coffee is left to sit out?

Here are the things that will happen if coffee is left to sit out:

1. The flavor of your coffee will deteriorate. 

Coffee that is left to sit out undergoes a chemical reaction called oxidation, a process wherein a chemical substance changes because of the addition of oxygen. This is what makes your coffee go stale. The process involves electrons that are transferred from one molecule to another. 

The flavor of coffee is made up of volatile aromatic compounds that oxidize quickly upon contact with oxygen especially when in a room with high temperature. If you notice, the flavor of cold brew coffee is preserved much longer compared to hot brew coffee. Once brewed coffee cools after 30 minutes most of the pleasant flavor and aroma is also lost. If coffee is left to sit out overnight, the flavor substances evaporate in the air. 

What to do:  

You can keep the flavors in your coffee a little longer by letting it sit in an airtight container. This way the oxidation reaction will be limited. You can also keep your brew in the refrigerator where the temperature is low as it decreases the rate with which coffee loses its aroma. Just place it in an airtight container so it won’t pick up the flavors of other items inside the fridge. 

2. The milk in your coffee will go bad in two hours. 

If you are fond of coffee and milk combinations, you should not let it sit out for more than two hours.  Milk becomes hazardous food, along with eggs and meat, if placed in temperatures beyond 40 and up to 140 degrees Fahrenheit. These temperatures are referred to as a danger zone since bacteria grow rapidly within this range. 

What to do:

For hot coffee with milk such as a latte, make sure not to sit it out for more than an hour while the iced latte should not sit out for more than two hours. Avoid reheating coffee with milk since it could only lead to digestive discomfort. 

3. Coffee oils become rancid. 

If coffee is left to sit out for a few hours, the coffee oils will become rancid.  The interaction between oxygen and coffee oils results in rancidity and rancidification is among the reactions to the oxidation process which leads to an unpleasant coffee flavor. Free radicals will also begin to form causing oxidative stress which is dangerous to human health. 

What to do:

To reduce the rancidification of coffee oils, make sure to store your unfinished coffee in an opaque and airtight container and keep it in the refrigerator to further slow down the process. 

4. Bacteria and molds begin to appear. 

Coffee that has been left to sit out for a long time will start to grow mold. This is usually the case if it is around four to seven days after brewing and if left at room temperature.  Another factor that could contribute to the growth of molds is your coffee maker or coffee pot since bacteria and mold can thrive in them. 

What to do:

Make sure that your coffee maker or coffee pot is cleaned regularly to avoid bacteria and mold growth.  Reheating coffee may also kill them but will affect the overall flavor of your brew. 

Aside from these factors mentioned above, a favorable outcome of coffee that is left to sit out is that the caffeine content is preserved. Caffeine won’t degrade because it is stable and will retain its energizing properties for weeks after brewing. 


Coffee that has been left to sit out is still safe to consume but only for a certain time. Black brewed coffee is still drinkable even after a day and at room temperature but you won’t be able to enjoy the original flavor. If placed in the fridge it can last for a week while cold brew can reach up to 14 days. However, if you are into lattes or cappuccinos, you should discard it if it is already beyond two hours.  

Image: / Thiago Santos