How Long Breathalyzers Can Detect Alcohol: Information!

Discover how long breathalyzers can detect alcohol. It’s easy to know.


I.   Calculating Detection Time

II.  Keep in Mind

III. Caution

IV.  How to Keep BAC Low

V.   Have Pleasure Without Pain

I. Calculating Detection Time.

Basically, two things determine how long a breathalyzer can detect alcohol. One is person’s blood alcohol concentration (BAC) level. The other is how long ago they drank. (“Breathalyzer” is really a brand name of an alcohol breath detector. Other names include Intoximeter, Draeger, Alcopro, BACtrack, Alcosensor, BAC Datamaster, and Intoxilyzer.)

BAC declines at about .015 per hour. Thus, if the person’s peak BAC is a very high .15, it would be zero in ten hours. That is, dividing .015 into .15 equals 10. Similarly, if the BAC is .08, it would be gone in about  5.33 hours. That would be about an hour and 20 minutes. If it’s .05, it would take about three about three hours and twenty minutes. (.05 divided by .015). In short, simply divide the BAC by .015.

II. Keep in Mind

long breathalyzersFor most adults, it’s not illegal to drive with a BAC below .08. However, the lower the BAC, then safer the driving. Legally, it’s not wise to drink too near the limit. That’s because breathalyzers are not highly accurate. Therefore, you could be driving with a legal but still get a conviction of DUI or DWI. That is, with driving under the influence or while impaired. 

It’s important to remember that BAC can continue to rise after drinking ends. So it’s important to calculate from the peak BAC. A number of small, hand-held breathalyzers are on the market to help identify your BAC. But like all alcohol breath testers, they may be inaccurate. So driving well below the illegal BAC is wise. Of course, it’s even better to drive with zero BAC.

III. Caution

long breathalyzersAlthough breathalyzers are not highly accurate, field sobriety tests are much worse. The chances of passing a breathalyzer test are much higher than a field sobriety test. About 30% of volunteers with zero BAC who take a field sobriety test fail it. And that’s under ideal conditions.

However, police never give field sobriety tests under ideal conditions. And the drivers they pull over for suspected DUI fear failing and going to jail. They are very nervous and have a hard time concentrating. Police usually give the test at night, on a very uneven surface, with distracting lights and traffic nearby. 

Unfortunately, the test is highly subjective. Worse, the officer who pulls you over believes you’re probably guilty. So no matter how objective the officer tries to be, it’s essentially impossible. In addition, there often incentives to increase the number of arrests.

Therefore, DUI defense attorneys urge drivers not to take field sobriety tests. They suggest that breathalyzers are less biased. For more, visit Never Take a Field Sobriety Test Say DUI Lawyers.

IV. How to Keep BAC Low

  • Eat while drinking.
  • Sip drinks slowly.
  • Pace drinks to no more than one per hour.
  • Enjoy a non-acoholic drink between alcoholic ones.
  • Accept an alcoholic drink only when it fits with your consumption schedule.
  • Have only standard drink sizes to keep track of your alcohol consumption. Standard drinks of beer, wine, and spirits have the same amount of alcohol. A breathalyzer can’t tell them apart.

long breathalyzersA standard drink is

  • 5 ounces of dinner wine.
  • 12 ounces of regular beer.
  • 1 and 1/2 ounce of spirits. That’s whiskey, rum, vodka, gin, tequila, etc.

V. Have Pleasure Without Pain

People usually find that having a few drinks makes them feel good. So they assume that having more drinks will make them feel even better.

However, that’s not what happens. In reality, more drinks make them feel bad. This is the biphasic or two-part effect of drinking alcohol.

This is how it works. People tend to feel better as their BAC rises up to about .05. (Actually, it’s .055. That’s helfway between .05 and .06.) But as people’s BAC rises higher, negative effects begin. They’re more likely to have hangovers or worse hangovers. Also, other problems tend to increase.

So the good phase is a BAC up to .055. The bad phase begins after the BAC goes over that level. Obviously, it’s smart to avoid going into the second phase.

Learn how to estimate BAC and discover more at How Alcohol Effects Us. The Biphasic Curve Shows the Pleasure vs Pain Relationship.