BAC Calculator for San Francisco, California

Q: What is the BAC limit in San Francisco?

The legal BAC limit for drivers in San Francisco, California is 0.08%. For drivers under 21, the limit is effectively 0.00–0.02% under zero-tolerance laws. For commercial (CDL) drivers, the federal limit of 0.04% applies.

Q: How many drinks is the legal limit in San Francisco?

The number of drinks that puts you at the 0.08% limit varies significantly by body weight, sex, and how quickly you drink. As a rough guideline, a 160-pound male may reach 0.08% after 3–4 drinks in one hour. Women and lighter individuals reach the limit with fewer drinks. Use our free BAC calculator for a personalized estimate.

Q: What are DUI penalties in California?

A first-offense DUI in California typically carries fines, potential jail time, and license suspension. Penalties increase significantly for repeat offenses, high BAC readings (0.15%+), or if a minor was present in the vehicle. See our full California DUI laws page for detailed penalty information.

Alex Harmon · Updated June 2026

Key Facts for San Francisco Drivers

Legal BAC Limit 0.08%

State California

Under-21 Limit 0.00–0.02%

CDL (Commercial) Limit 0.04%

Implied Consent Yes

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DUI Law in San Francisco, California

San Francisco has some of the highest DUI enforcement density in California. SFPD, California Highway Patrol, and BART Police all operate in the city, and popular neighborhoods like the Mission, the Castro, North Beach, and the Marina are heavily monitored. SF's compact geography and excellent transit system make it easier to avoid driving after drinking than in almost any California city.

SF's MUNI Metro, BART subway, and extensive bus network make San Francisco one of the best-served US cities for transit, with late-night options available most nights. The 24-hour BART on weekends makes driving after drinking genuinely unnecessary.

California DUI first-offense penalties apply throughout San Francisco: fines from $390 plus penalty assessments (total ~$2,000+), potential 96-hour to 6-month jail, 6-month license suspension, and mandatory DUI school.

How Many Drinks to Reach the Limit in San Francisco?

The 0.08% BAC limit in San Francisco means different things for different people. The Widmark formula — the standard method for estimating BAC — depends on body weight, biological sex, number of drinks, and time elapsed. Here are rough estimates for reaching 0.08% BAC:

120 lb (54 kg) female: approximately 2–3 standard drinks in 2 hours
150 lb (68 kg) female: approximately 3–4 standard drinks in 2 hours
160 lb (73 kg) male: approximately 3–4 standard drinks in 2 hours
200 lb (91 kg) male: approximately 4–5 standard drinks in 2 hours

These are estimates only. Individual metabolism, food intake, and drink strength all affect actual BAC. The only reliable way to know your BAC is to use a calibrated breathalyzer or estimate with our BAC calculator.

Sobering Up After Drinking in San Francisco

Your liver eliminates alcohol at approximately 0.015% BAC per hour — regardless of coffee, food, water, or activity. If your BAC is 0.08% when you stop drinking, you will need approximately 5.3 hours before reaching zero. There is no shortcut.

Common myths: coffee does not speed up metabolism, cold water does not lower BAC, and "sleeping it off" only works if enough time passes. The only thing that sobers you up is time.

For a full breakdown of elimination rates and timing, see our How Long to Sober Up guide.

California DUI Laws: What You Need to Know

For complete information on California's DUI statutes, penalties, license suspension rules, and ignition interlock requirements, see our dedicated state page:

Frequently Asked Questions

What is the BAC limit in San Francisco?

The legal BAC limit in San Francisco, California is 0.08% for drivers 21 and over. Drivers under 21 are subject to zero-tolerance laws (0.00–0.02% depending on state). Commercial CDL drivers are held to a stricter 0.04% federal limit.

How many drinks is the legal limit in San Francisco?

The number of drinks to reach 0.08% varies by body weight and sex. As a rough guide, a 160-pound male may reach 0.08% after 3–4 drinks in one hour. Women and lighter-weight individuals reach the limit with fewer drinks. Use our BAC calculator for a personalized estimate based on your specific weight and drinking pace.

What are DUI penalties in California?

A first-offense DUI in California typically includes fines, potential jail time, and license suspension. Penalties are enhanced for high BAC readings (0.15%+), repeat offenses, or if a minor was in the vehicle. See our full California DUI laws page for complete penalty tables.

Facing a DUI Charge?

A DUI conviction costs $10,000–$25,000 on average. An experienced DUI attorney may challenge the stop, question the breathalyzer, or negotiate reduced charges.

FIND A DUI ATTORNEY →

Know Your BAC Before You Drive

Personal breathalyzers give you an accurate reading in seconds. The BACtrack Mobile connects to your phone and uses the same fuel cell technology as law enforcement devices.

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