Time to Sober Calculator: How Long Until You're Sober?

The Basic Rule: 0.015% BAC Per Hour

Your body eliminates alcohol at a remarkably consistent rate: approximately 0.015% BAC per hour. This rate, known as the elimination rate or metabolic rate, is determined primarily by your liver's capacity to process alcohol and remains fairly constant regardless of your weight, gender, or how much you've had to drink.

This means if your current BAC is 0.08% (the legal limit in most U.S. states), you'll need approximately 5.3 hours to reach 0.00% BAC:

For example: 0.08% ÷ 0.015 = 5.33 hours

However, this simple formula has important limitations. Individual metabolism rates can range from 0.010% to 0.020% per hour. If you metabolize alcohol more slowly than average, it could take 8 hours to clear a 0.08% BAC. To be safe, always use the more conservative 0.010% rate when planning.

Time to Sober Reference Table

This table shows approximately how long it takes to reach 0.00% BAC from various starting points, using the average elimination rate of 0.015% per hour:

How Alcohol Metabolism Works

Understanding how your body processes alcohol helps explain why the sobering process takes so long and why nothing can speed it up.

The Liver's Role

Your liver is responsible for metabolizing approximately 90-95% of the alcohol you consume. The remaining 5-10% is eliminated through breath, sweat, and urine - which is how breathalyzers work.

The liver uses two main enzymes to break down alcohol:

1. Alcohol Dehydrogenase (ADH): This enzyme converts ethanol (drinking alcohol) into acetaldehyde, a toxic compound that causes many hangover symptoms. This is the rate-limiting step - your liver can only produce so much ADH, which is why metabolism rate is relatively constant.

2. Aldehyde Dehydrogenase (ALDH): This enzyme quickly converts acetaldehyde into acetate, which is then broken down into carbon dioxide and water for elimination.

The liver can process approximately one standard drink (14 grams of alcohol) per hour. When you drink faster than this rate, alcohol accumulates in your bloodstream, causing BAC to rise. When you stop drinking, the liver works through this backlog at its steady rate.

First-Order vs. Zero-Order Kinetics

Interestingly, alcohol metabolism follows zero-order kinetics at typical drinking levels, meaning it's processed at a constant rate regardless of concentration. This is different from most substances, which are eliminated faster when concentrations are higher (first-order kinetics).

This zero-order elimination is why BAC decreases in a straight line rather than a curve. Whether your BAC is 0.08% or 0.20%, your liver eliminates approximately 0.015% per hour.

At very low BAC levels (below about 0.02%), metabolism may shift to first-order kinetics, which is why the final bit of alcohol may clear slightly faster than predicted.

Factors That Affect Sobering Time

While the average elimination rate is 0.015% per hour, several factors cause individual variation:

Genetic Factors

Genetic variations in ADH and ALDH enzymes significantly affect metabolism rate. Some people have "fast" versions of these enzymes that process alcohol more quickly, while others have slower versions.

Many people of East Asian descent have a variant of ALDH that works slowly, causing acetaldehyde to accumulate and producing facial flushing, nausea, and rapid heartbeat. This doesn't necessarily mean they sober up faster - the alcohol is still processed at a normal rate, but the intermediate steps cause unpleasant effects.

Biological Sex

Women generally have lower levels of ADH in the stomach than men, which means more alcohol enters the bloodstream directly. However, once alcohol is in the blood, elimination rates are similar between men and women.

Some studies suggest women may actually metabolize alcohol slightly faster than men once it's in the bloodstream, potentially due to liver size relative to body weight. But these differences are small compared to genetic variation.

Age

Alcohol metabolism slows with age. Older adults typically have less efficient liver function and less body water, leading to higher peak BAC and longer elimination times. A 60-year-old may take 20-30% longer to sober up than a 25-year-old.

Liver Health

Liver damage from hepatitis, cirrhosis, or fatty liver disease significantly impairs alcohol metabolism. People with liver disease may have elimination rates as low as 0.005% per hour, meaning sobering takes three times longer than average.

Recent Food Intake

While food doesn't speed up elimination, it does affect peak BAC. Eating before or while drinking slows absorption, resulting in a lower peak BAC that takes less time to clear. The total elimination time from first drink to zero BAC may be similar, but the time spent at potentially dangerous levels is reduced.

Chronic vs. Occasional Drinking

Regular heavy drinkers may develop higher elimination rates due to enzyme induction - the liver produces more alcohol-metabolizing enzymes in response to frequent alcohol exposure. Some chronic heavy drinkers have elimination rates of 0.020% or higher per hour.

However, this "faster" metabolism comes with serious health costs and doesn't reduce impairment at a given BAC level.

What Doesn't Speed Up Sobering

Despite popular belief, nothing can accelerate alcohol metabolism. Your liver works at its own pace, and these common "remedies" are myths:

Coffee and Caffeine

Coffee does not sober you up. Caffeine is a stimulant that can make you feel more alert, but it doesn't reduce BAC or improve coordination or judgment. Studies show that caffeinated drunk drivers are just as impaired as non-caffeinated drunk drivers - they're simply more awake. This can actually be dangerous, as feeling alert may lead someone to believe they're capable of driving when they're not.

Cold Showers

A cold shower will wake you up and may temporarily increase alertness, but it has zero effect on BAC. The shock of cold water doesn't change liver enzyme activity or speed alcohol elimination in any way.

Exercise

Working out or being physically active doesn't metabolize alcohol faster. While exercise does increase metabolism of many substances, alcohol elimination is limited by liver enzyme capacity, not overall metabolic rate. You might sweat out a tiny amount of alcohol, but it's insignificant compared to what the liver processes.

Eating After Drinking

Eating food after you've already absorbed alcohol doesn't reduce BAC. Food only helps if consumed before or during drinking, when it slows absorption. Once alcohol is in your bloodstream, food has no effect on elimination rate.

Fresh Air

Going outside for fresh air might make you feel better and more alert, but it doesn't change BAC. The idea that you can "walk it off" is a dangerous myth.

Activated Charcoal

While activated charcoal can absorb some toxins in the stomach, it's not effective for alcohol. Alcohol is absorbed too quickly and too completely for charcoal to have any meaningful effect, especially after the first few minutes of drinking.

IV Fluids and "Hangover Cures"

IV hydration services and hangover remedies may help with dehydration and electrolyte imbalance, but they don't speed up alcohol elimination. Any claims to "flush out" alcohol faster are unsupported by evidence.

Calculating Your Sobering Time

To estimate when you'll be sober, follow these steps:

Step 1: Estimate Your Current BAC

If you don't have a breathalyzer, you can estimate BAC using the Widmark formula or our BAC calculator. You'll need to know:

• Number of standard drinks consumed
• Your body weight
• Your biological sex
• Time since you started drinking

Step 2: Determine Your Target

What BAC do you need to reach?

• 0.00% - Completely sober (recommended for driving)
• 0.08% - Legal driving limit in most states
• 0.04% - Legal limit for commercial drivers
• 0.02% - Limit for drivers under 21 in many states

Step 3: Calculate the Time

Subtract your target BAC from your current BAC, then divide by the elimination rate:

For safety, use the conservative elimination rate of 0.010% per hour rather than the average of 0.015%.

Step 4: Add a Safety Buffer

Because of individual variation and estimation errors, add at least 30% extra time to your calculation. If your math says 5 hours, plan for 6.5 hours.

Also remember that if you've recently stopped drinking, your BAC may still be rising. Peak BAC typically occurs 30-90 minutes after your last drink.

Example Calculations

Example 1: After a Night Out

You stopped drinking at midnight with an estimated BAC of 0.12%. When can you drive?

Using average rate (0.015%):

Time to reach 0.08%: (0.12 - 0.08) ÷ 0.015 = 2.7 hours = 2:40 AM

Time to reach 0.00%: 0.12 ÷ 0.015 = 8 hours = 8:00 AM

Using conservative rate (0.010%):

Time to reach 0.08%: (0.12 - 0.08) ÷ 0.010 = 4 hours = 4:00 AM

Time to reach 0.00%: 0.12 ÷ 0.010 = 12 hours = 12:00 PM noon

Recommendation: Wait until at least 8 AM for the legal limit, noon to be completely safe. Better yet, don't drive until the afternoon.

Example 2: Afternoon Happy Hour

You have two drinks between 5 PM and 6 PM, reaching an estimated BAC of 0.05%. When are you safe to drive home?

Using conservative rate:

Time to reach 0.00%: 0.05 ÷ 0.010 = 5 hours = 11:00 PM

Since you're already under the legal limit, you could legally drive sooner, but waiting until 11 PM ensures you're completely sober.

Example 3: Morning After Calculation

You drank heavily until 2 AM, reaching an estimated peak BAC of 0.18%. You need to drive to work at 8 AM. Are you safe?

6 hours elapsed (2 AM to 8 AM)

Using average rate: 0.18 - (0.015 × 6) = 0.18 - 0.09 = 0.09% BAC

Using conservative rate: 0.18 - (0.010 × 6) = 0.18 - 0.06 = 0.12% BAC

Result: You're likely still over the legal limit at 8 AM. You should not drive to work. Consider calling in sick, working from home, or arranging alternative transportation.

The "Morning After" Problem

Many DUI arrests occur the morning after heavy drinking. People assume that sleeping "sobers them up," but sleep has no effect on alcohol metabolism. If you go to bed very intoxicated, you may still be over the legal limit when you wake up.

Studies of "morning after" BAC levels have found:

• About 26% of people who drank heavily the night before were still over 0.05% BAC at 8 AM
• About 12% were still over 0.08% BAC at 8 AM
• Residual alcohol impairment was detected even in those who reached 0.00% BAC

The last point is important: even after BAC reaches zero, residual impairment from sleep deprivation, dehydration, and hangover effects can reduce driving ability. Research shows that hungover drivers perform similarly to drivers at 0.05-0.08% BAC in driving simulator tests.

Using Personal Breathalyzers

Personal breathalyzers can help estimate your BAC, but they have limitations:

Accuracy varies widely: Consumer breathalyzers can have error margins of ±0.01-0.02% BAC. A reading of 0.07% might actually be 0.05% or 0.09%.

Calibration is essential: Breathalyzers need regular calibration (typically every 6-12 months) to maintain accuracy. An uncalibrated breathalyzer can give dangerously incorrect readings.

Technique matters: Proper use requires waiting 15-20 minutes after your last drink, not eating or smoking, and following the device's specific instructions.

False confidence risk: A breathalyzer showing 0.07% might lead you to believe you're safe to drive. But given the error margin, you could actually be at 0.09%. Always treat breathalyzer readings as estimates, not definitive measurements.

If you're going to use a personal breathalyzer, choose a fuel cell sensor model (more accurate than semiconductor sensors) and keep it calibrated. Even then, if the reading is anywhere close to the legal limit, don't drive.

Legal Implications

Understanding sobering time has important legal implications:

DUI checkpoints: Police conduct checkpoints at various times, including early mornings when people may still be impaired from the night before.

Zero tolerance laws: Drivers under 21 face very low BAC limits (0.00-0.02%) in most states. Even one drink might keep you over the limit for hours.

Enhanced penalties: Many states have enhanced penalties for BAC levels of 0.15% or higher. If you reach such levels, you'll need 10+ hours to reach zero BAC.

Implied consent: In all states, having a driver's license implies consent to BAC testing. Refusing a test typically results in automatic license suspension.

Per se laws: In all states, it's illegal to drive with BAC at or above 0.08%, regardless of whether you "feel impaired." The BAC number alone is sufficient for conviction.

Practical Tips for Planning Ahead

The best way to avoid sobering time concerns is to plan ahead:

Designate a sober driver: Before drinking begins, choose someone who won't drink at all.

Use rideshare services: Uber, Lyft, and taxis are always safer than driving after drinking, regardless of how much time has passed.

Stay overnight: If drinking at a friend's house or near a hotel, arrange to sleep there rather than driving home.

Limit consumption: One drink per hour roughly matches your metabolism rate. Staying at this pace keeps BAC relatively stable and low.

Track your drinks: Use an app or simply count to know exactly how much you've consumed.

Set an alarm: If you need to drive in the morning, set an alarm that accounts for sobering time plus a safety buffer.

When in doubt, don't drive: If there's any question about whether you're sober, the answer is don't drive. The consequences of a DUI conviction far outweigh the inconvenience of finding alternative transportation.

Try Our Time to Sober Calculator

Use our free time to sober calculator to get a personalized estimate of when you'll reach your target BAC. Enter your current BAC (measured or estimated) and see exactly when you'll be safe.

Remember: These calculations are estimates only. Individual results vary significantly based on genetics, liver function, and other factors. The only guaranteed way to be safe to drive is to not drink at all, or to wait until you're absolutely certain all alcohol has cleared your system.