SipLogger — Educational BAC Calculator & Drink Tracker
Understand Alcohol Metabolism. Visualize Your Estimated BAC Curve.
Educational and informational BAC estimation tool for iPhone & iPad. No account. No ads. No data collection.
For educational & informational purposes only. Rated 18+.
SipLogger is a free educational BAC calculator and alcohol tracker for iPhone that estimates your blood alcohol level over time using the Watson Total Body Water method and the Widmark formula — with no ads, no subscription, and no data collection.
These established pharmacokinetic models are personalized by your weight, height, sex, and age. Use it as a drink counter with 40+ built-in drink templates or create custom entries. Observe how drink pace and timing affect your estimated BAC curve, see when your level approaches baseline, and review session history to understand your patterns — all with HealthKit integration and Live Activities for at-a-glance monitoring on your Lock Screen and Dynamic Island.
Not a breathalyzer — all BAC values are mathematical estimates with approximately ±20% variance. For educational and informational purposes only. Available in 8 languages with metric and imperial support.
See the Educational BAC Calculator in Action
Educational BAC Estimation — Key Features
Educational Estimated BAC Curve
View your estimated blood alcohol content as a smooth chart over time. Observe estimated absorption, peak, and metabolism phases — designed to help you understand how alcohol affects the body. All values are approximations (+/-20%).
Watson + Widmark Formulas
Uses the Watson Total Body Water method combined with the Widmark formula for scientifically-grounded estimation. Personalized by weight, height, biological sex, and age. All values are approximations (+/-20%).
40+ Built-In Drinks
Choose from a curated library of 40+ drink templates — beer, wine, spirits, cocktails, and more. Each has pre-configured volume and ABV. Create custom drinks with any volume and alcohol percentage.
Drink Pace Modeling
Each drink's estimated absorption is modeled individually based on timing. Observe how spacing may affect your estimated BAC curve — for educational understanding only.
HealthKit Integration
Optionally read weight, height, biological sex, and age from Apple HealthKit for more accurate educational estimates. Read-only — SipLogger never writes to HealthKit and never transmits your health data.
Session History & Diary
Review past sessions with detailed drink logs, estimated peak BAC, session duration, and time to approach baseline. A personal educational diary of your drinking patterns.
Live Activities
Monitor your active session from the Lock Screen and Dynamic Island with Live Activities. See your current estimated BAC and time to approach baseline at a glance.
8 Languages
Available in English, Ukrainian, Polish, French, Spanish, German, Czech, and Italian. Full localization with metric and imperial measurement support.
How the Educational BAC Calculator Works
Set Up Your Profile
Enter your weight, height, sex, and age — or let SipLogger read them from HealthKit. These values personalize the Watson + Widmark formula.
Log Your Drinks
Pick from 40+ templates or create custom drinks. Each drink is timestamped for accurate absorption modeling in the estimated BAC calculation.
Review Your Sessions
See your estimated BAC curve, review session history, and learn how different drinking patterns affect estimated alcohol metabolism.
Why SipLogger Is Completely Free
No Subscription, No Ads
SipLogger is 100% free with no subscription, no ads, no in-app purchases, and no hidden costs. Every feature is available from day one.
Complete Privacy
No backend servers. No account required. No analytics in the app. All data stays on your device. Your drinking data is nobody's business but yours.
Educational Mission
SipLogger exists as an educational and informational tool to help people understand alcohol metabolism. Knowledge promotes responsible decision-making.
Metric & Imperial
Switch between measurement systems based on your preference — milliliters or fluid ounces, kilograms or pounds.
Frequently Asked Questions
Is SipLogger really free?
Yes, SipLogger is 100% free with no subscription fees, no ads, and no in-app purchases. It is an educational tool for understanding alcohol metabolism. All features are available immediately with no restrictions.
How does the estimated BAC calculation work?
SipLogger uses the Watson Total Body Water (TBW) method combined with the Widmark formula to estimate blood alcohol content. The calculation considers your weight, height, biological sex, and age to model how alcohol is absorbed and metabolized over time. Results are educational estimates with approximately ±20% accuracy.
How accurate is the estimated BAC?
The estimated BAC has approximately ±20% accuracy. Individual metabolism varies based on many factors including food intake, hydration, medications, liver health, and genetics. SipLogger is for educational and informational purposes only — never use estimated BAC to make decisions about driving or operating machinery.
Does SipLogger tell me when I can drive?
No. SipLogger is an educational tool and never provides driving advice. The app shows when your estimated BAC approaches baseline levels, but this should never be used to determine fitness to drive. Always use a certified breathalyzer or wait a safe amount of time. When in doubt, use a taxi or rideshare.
Is my data private?
Yes, SipLogger has no backend servers, requires no account, and collects no data. All your drink logs and session history stay entirely on your device. HealthKit data is read-only and never leaves your device. The app contains no analytics, no tracking, and no third-party SDKs.
What HealthKit data does SipLogger use?
SipLogger optionally reads weight, height, biological sex, and date of birth from HealthKit to improve estimated BAC accuracy. This data is only used locally for calculations — it is never transmitted, stored externally, or shared. SipLogger never writes data to HealthKit.
How many drinks are in the built-in database?
SipLogger includes 40+ built-in drink templates covering beer, wine, spirits, cocktails, and more. Each template has pre-configured volume and alcohol percentage. You can also create custom drinks with any volume and ABV percentage.
What is the Widmark formula?
The Widmark formula is a well-established pharmacokinetic model for estimating blood alcohol content. It calculates estimated BAC based on the amount of alcohol consumed, body weight, a gender-specific distribution ratio, and time elapsed. SipLogger enhances this with the Watson Total Body Water method for improved body water estimation, making it a reliable educational tool.
Does SipLogger work on iPad?
Yes, SipLogger is a universal app that works on both iPhone and iPad. The interface adapts to larger screens for a comfortable experience on iPad.
What is the age rating for SipLogger?
SipLogger is rated 18+ on the App Store. The app is intended for adults of legal drinking age. It is an educational and informational tool — it does not encourage or promote alcohol consumption.
What is the best free BAC calculator app for iPhone?
SipLogger is a free educational BAC calculator for iPhone that uses the Watson TBW and Widmark formula to estimate blood alcohol content over time. Unlike many alternatives, SipLogger has no ads, no subscription, no in-app purchases, and collects no data. It includes 40+ drink templates, a real-time BAC curve, Live Activities, HealthKit integration, and is available in 8 languages.
How long until my estimated BAC reaches baseline?
SipLogger shows your estimated BAC curve over time so you can see when your level is projected to approach baseline. Alcohol is generally metabolized at roughly 0.015% BAC per hour, but individual rates vary. SipLogger models this using the Watson TBW and Widmark formula personalized to your body. This is an educational estimate only — never rely on any app or calculator to determine fitness to drive.
Is SipLogger a breathalyzer app?
No. SipLogger is not a breathalyzer and does not measure actual blood alcohol. It is an educational calculator that mathematically estimates BAC based on your drinks, body parameters, and time using the Watson TBW and Widmark formula. Results have approximately ±20% variance. For precise measurement, use a certified breathalyzer device.
Does SipLogger support Live Activities and Dynamic Island?
Yes. SipLogger uses Live Activities to show your current estimated BAC and session timer on your iPhone Lock Screen and Dynamic Island. This lets you monitor your estimated level at a glance without opening the app.
What is a standard drink?
A standard drink contains approximately 14 grams (0.6 oz) of pure alcohol — roughly equivalent to a 12 oz beer at 5% ABV, a 5 oz glass of wine at 12% ABV, or a 1.5 oz shot of spirits at 40% ABV. SipLogger's 40+ built-in drink templates are pre-configured with standard volumes and ABV percentages to help you log drinks accurately for educational BAC estimation.
Does SipLogger work offline?
Yes. SipLogger works entirely offline with no internet connection required. All calculations happen on your device. There are no backend servers, no cloud sync, and no data transmission — your drinking data never leaves your iPhone or iPad.
Your Privacy Is Absolute
No account required. No backend servers. No analytics. No data collection. All your drink logs and session data stay on your device. HealthKit data is read-only and never transmitted. SipLogger is a completely private, educational tool.