The 0.04% Standard
Half the limit. Double the consequences. Understanding the BAC threshold that defines your career.
The CDL Difference
Standard Driver
0.08%
Legal BAC Limit
CDL Holder
0.04%
Half the Limit
The Math Problem
For an average 180-pound person:
- •2 beers over an hour might put you at 0.05%
- •For your neighbor with a regular license: Completely legal
- •For you as a CDL holder: Career-ending if in a CMV
The margin for error is razor-thin. What feels like "barely buzzed" to most people can cost you your CDL.
The "Buzzed" Zone: Where CDL Holders Lose
| BAC Level | Standard Driver | CDL in CMV |
|---|---|---|
| 0.00% - 0.02% | Legal | Legal |
| 0.02% - 0.04% | Legal | 24-Hour Out-of-Service |
| 0.04% - 0.08% | Legal | 1-Year CDL Disqualification |
| 0.08%+ | DUI | 1-Year Disqualification + Criminal DUI |
Note: The 0.04% limit applies when operating a CMV. For personal vehicle DUI (0.08%+), see our Personal Vehicle DUI guide.
The 24-Hour Out-of-Service Order
What Happens at 0.02% - 0.04%
Even if you're below the 0.04% threshold, any detectable alcohol triggers an immediate 24-hour out-of-service order. You cannot perform any safety-sensitive function—including driving, loading cargo, or even waiting at a dispatch terminal.
What It Means
- • Immediate removal from duty
- • Cannot drive for 24 hours
- • Logged in your record
- • Employer notification
What It Doesn't Mean
- • Not a CDL disqualification
- • Not reported to Clearinghouse
- • Not a criminal charge
- • But: employer may still terminate
Understanding BAC Estimation
BAC varies based on body weight, gender, food intake, and drinking pace. Here's a rough guide for a 180-pound male drinking standard drinks (12 oz beer, 5 oz wine, 1.5 oz liquor):
| Drinks (1 hr) | Est. BAC | Standard Driver | CDL (CMV) |
|---|---|---|---|
| 1 drink | ~0.02% | Legal | Out-of-Service Risk |
| 2 drinks | ~0.04-0.05% | Legal | DQ Risk |
| 3 drinks | ~0.06-0.07% | Legal | 1-Year DQ |
| 4+ drinks | ~0.08%+ | DUI | DQ + DUI |
Disclaimer: These are rough estimates only. Actual BAC varies significantly based on individual factors. The only safe approach is to never operate a CMV with any alcohol in your system.
Key Takeaways
The 0.04% Rule
Operating a CMV at 0.04% BAC or higher triggers immediate 1-year CDL disqualification, even without a criminal DUI conviction.
Any Detectable = Grounded
Even below 0.04%, any detectable alcohol (0.02%+) means 24 hours off the road. One beer could sideline you for a full day.
Personal Vehicle Different Rule
The 0.04% limit applies to CMV operation. Personal vehicle DUI (0.08%+) also disqualifies your CDL—see our separate guide.
No Margin for Error
What feels like "one or two drinks" to most people can end your career. The safest approach: no alcohol before driving.
Related Guides
Sources & Official Resources
Information on this page is sourced from federal regulations.
Last updated: January 8, 2026
Charged Near the 0.04% Threshold?
BAC readings can be challenged. Breathalyzer calibration, timing of the test, and procedural errors all create defense opportunities. Talk to an attorney who understands CDL cases.
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