How Long Can a Beer Sit Out Open? Understanding Beer’s Shelf Life 

For most of us, a beer’s shelf life is the first thing that springs to mind before we purchase. Some say the beverage – whose feel-good effect is unmatched – can last months. But others argue even the best craft beers are only fresh for a few days. 

A beer’s shelf life depends on many factors, including whether it’s open or not. A bottled beer appropriately stored can last up to half a year! However, that quickly changes the moment you crack open that bottle. 

So, how long can a beer sit out open? 

This article strives to quench your curiosity by exploring how long an open beer can last. Read ahead to discover the elements that affect the drink’s shelf life, signs of spoilage, and a few valuable tips for preserving beer.

How Long Can Beer Sit Out Open?

The clock starts ticking on a beer’s freshness as soon as you expose it to the elements.  Generally, a sealed beer can stay at its optimal quality for about 4 to 6 months when stored at room temperature. 

However, if you crack open a beer bottle, it’s only fresh for 1-2 days, so you should drink it within that period to enjoy its best flavor.  Of course, you can still drink it after three days without exposing yourself to any health hazards, but its taste will be far from pleasant. 

3 Factors Affecting Beer’s Shelf Life

  1. Temperature

Temperature plays a pivotal role in determining an open beer’s shelf life.  If you store it in a warm place above room temperature, its freshness will decrease quickly.  On the flip side, storing it in your refrigerator prolongs its freshness. 

Ideally, you should store beer at typical refrigerator conditions—35°F and 46°F. 

If you don’t have a fridge, choose a cool, dark place that is undisturbed by regular movements, such as a pantry or cellar.  Your beer will likely last longer since the areas’ temperatures are lower in these areas. 

  1. Exposure to Light

Have you ever wondered why people store beer in dark bottles? The main reason is to protect the drink against its archenemy—UV rays!  

The sun’s rays are notorious for shortening beer’s shelf life. They penetrate the beverage’s bottles and trigger a chemical reaction that breaks down its taste components, causing flavor deterioration.

This damaging process is more prominent in beers like India Pale Ales and other light beers that are best consumed within three months after packaging. 

Unfortunately, the insidious effects of UV exposure don’t end with bottled beer. Craft varieties such as IPAs, Pale Ales, Kolsch, and Amber also experience degradation due to light if not stored properly in dark places. 

  1. Oxygen Exposure

Oxygen exposure is another significant factor that affects beer’s shelf life and quality.  

When oxygen comes into contact with the beer, it can cause oxidation, degrading the beverage’s flavor and changing its color. 

Bottled beer is particularly susceptible to oxygen exposure compared to canned beer. Store beer upright to reduce the surface in contact with oxygen to minimize this risk.  

Signs Your Beer Has Gone Bad 

Off Odors

Like any other product, spoiled beer develops a strange smell. If you detect any unpleasant odor, such as skunk or urine, it has already gone wrong, and you should not drink it. 

The presence of off odors could indicate the growth of bacteria or other microorganisms in the beer, meaning you can get sick if consumed. 

Interestingly, some people might tolerate expired beer’s “nasty” smells more. Even if you’re in that lot, consuming the spoiled beverage is still inadvisable. Therefore, pour the drink down the drain as soon as possible. 

Strange Tastes

Strange beer tastes are also a clear sign the beverage has expired. More often than not, these are metallic, sour, or cardboard-like flavors, usually resulting from bacterial contamination or extended exposure to oxygen. 

If you realize your beer has a strange flavor when you take your first sip, don’t drink it. You’re dealing with an expired batch and need to restock your fridge. 


Another indication of spoilage or bacterial contamination in beer is cloudiness. When bacteria are present, they can cause proteins and other compounds to clump together, leading to a cloudy appearance in the beverage.  The haze in beer is often accompanied by strange tastes or off odors. 

But note that not all beers with a hazy appearance are spoiled. Sometimes, it could mean the beverage hasn’t settled. Some craft beers also have some haze for flavor and texture. 

We recommend looking for other signs of spoilage before disposing of beer you suspect has gone bad. These could be unusual flavors and odors. 

Mold Growth

Mold growth on beer shows it’s bad, so you shouldn’t consume it. While unopened beer is unlikely to have mold due to the alcohol content and low pH level, issues during the bottling or canning process could result in mold growth even before opening.

Some craft beers may undergo wild fermentation, where mold growth occurs initially. But if it persists or appears anytime after that, it indicates spoilage. It’s crucial to ensure proper packaging and storage of opened beer to prevent mold formation.

Properly stored beer within its recommended shelf life will maintain its quality and taste without the risk of mold contamination.

How to Extend the Shelf Life of Beer

Are you wondering how you can ensure your beer lasts longer? Utilize these tried-and-tested tips: 

Find the Perfect Storage Spot 

We recommend storing beer in a cool, dry place with temperatures between 35 and 55 degrees Fahrenheit (2 to 13 degrees Celsius). Avoid areas prone to temperature fluctuations, such as near windows or heating vents.

At the same time, keep your beer away from light. Exposure to UV rays is one of the fastest ways to ensure your beer goes terribly, even before its expiry date. 

If you have a refrigerator, always store your beer in it. The machine’s cold temperature will slow down the beverage’s flavor degradation, giving you more time to enjoy it.

Keep the Beer Sealed and Upright

Here’s another excellent strategy to extend your beer’s shelf life. Ensure you properly seal your beer bottles or cans after opening them. This helps prevent oxygen exposure, which can cause the beverage to go bad faster. 

Again, store your beer upright rather than on its side. This helps minimize the surface area of the beer exposed to oxygen, further preserving its freshness.

Avoid Temperature Fluctuations

You should also avoid exposing your beer to temperature fluctuations to enable it to last longer. Rapid temperature changes can negatively impact the brew’s quality and taste. 

On top of that, never freeze and thaw your beer as it affects its carbonation levels and taste, facilitating spoilage.  If you’re storing the drunk outdoors, choose a shaded area that maintains a relatively stable temperature throughout the day.

Keep your beer in a cooler or insulated bag to shield it from extreme temperatures during transport.

FAQs On How Long Can A Beer Sit Open

How long can an open beer sit out before it goes bad?

Once you open a beer, drink it within 24-48 hours to relish its optimal taste and quality. After that time frame, the beverage will likely lose its carbonation, flavor, and freshness.

Can I still drink a beer that has been left out overnight?

You can drink an open beer left out overnight without exposing yourself to health risks. However, it will likely be flat without its initial flavor.

What happens if I refrigerate an opened beer after leaving it out?

Refrigerating an open beer after leaving it out can slow oxidation and preserve its freshness for a little longer. However, the overall quality and taste of the beer may still be affected as exposure to oxygen will continue even in cold temperatures.

Are there any visual signs or indicators that an open beer has gone bad?

Yes, an open beer that has gone bad will likely be darker or cloudy. You might also notice particles or sediment floating in the beverage. 
Off-smells like vinegar or rotten eggs and unusual flavors such as sourness or excessive bitterness are also common in spoiled beer. 
If you notice any of these signs, avoiding consuming the beer as they indicate spoilage or contamination is best.

Final Take on How Long Can a Beer Sit Out Open

An unsealed beer will only last 1-2 days. After that, it will be stale, and drinking it might be less exciting. Still, always watch out for the most common spoilage indicators before consuming the beverage to protect yourself against health hazards. Examples include off flavors and odors and mold growth. 

If you buy beer in bulk, take various measures to extend its shelf life. We recommend storing it in cool, dry areas or your refrigerators and limiting its exposure to sunlight. At the same time, keep your beer bottles and cans tightly sealed to ensure it remains fresh longer. 


Dan Smullen Beer is my life profile

Hi, I'm Dan, founder of BeerIsMyLife. I've been an avid homebrewer for over ten years, and beer is my true passion. I've traveled all over the world, visiting breweries, tasting beer, as well as making my own batches. I set up this blog to share that experience with you.