Frequently Asked Questions

Everything below applies to the free Alcophone app for Android and to the simplified calculator on this site. If your question is not here, it can be sent through the contact form.

The app

What does Alcophone do?

Alcophone estimates your blood alcohol content while you drink. You log what you have had, and the app shows your current estimated BAC, how it compares with the legal limit where you are, and the time it expects you to be back at zero. Once your BAC is above zero it keeps a ride-home button on screen, and at dangerous levels it offers a one-tap emergency call.

Is Alcophone free?

Yes. The full calculator, the database of 2,000+ beers, the legal limits and the rideshare shortcuts are free, supported by ads. A one-time premium unlock adds wine, spirits, cocktails, ciders and seltzers (5,800+ drinks in total), hydration tracking, a more personalised calculation with your body measurements and meals, and unlimited history, and removes the ads. There is no subscription.

Which countries does it support?

The United States, Canada, Australia, the United Kingdom, India and Ireland, including state, province and territory level limits, local drink sizes and the right emergency number for each. Support for more countries is in progress.

Does it work without an internet connection?

Yes. The BAC calculation runs entirely on your phone, so it keeps working with no signal, and you need no account. The rideshare shortcut needs the network because it hands over to another app; ads in the free version and the free-trial check also go online.

Accuracy and the science

How accurate is the estimate?

Alcophone builds its estimate from body composition rather than body weight alone, and calculates alcohol from the real volume and strength of what you logged. That is a substantial step up from the weight-only formula most calculators still use, and the premium model, which adds your circumference measurements, is more accurate still. It remains an estimate rather than a measurement, and food is one of the biggest things that move it, which is why Premium lets you log your meals.

How does Alcophone calculate blood alcohol?

From body composition rather than body weight alone. The app estimates your body fat percentage from your sex, age, weight and height, then works out the volume the alcohol spreads into: alcohol follows body water, which sits in fat-free mass, not in fat. Alcohol per drink is calculated from the actual volume and ABV of what you logged, not from a generic standard drink. A separate model is used for South Asian body composition.

Why do other BAC calculators give different numbers?

Most of them still run the Widmark formula from 1932, which knows only your weight and sex. Two people of the same weight with very different body composition get the same number from it. Alcohol spreads through body water, and body water sits in fat-free mass, not in fat — which is what Alcophone models. Where a weight-only formula differs, it tends to read low for people with higher body fat — the direction that matters least in your favour.

Can Alcophone replace a breathalyzer?

No. A breathalyzer measures a sample of your breath; Alcophone calculates from what you tell it. What the app can do that a breath test cannot is look forward: it shows what your BAC will be in three hours and when it reaches zero, which is the question that actually decides whether you can drive home.

Does eating change the result?

Yes, substantially. A full meal eaten before drinking slows absorption and can cut peak BAC by a third or more (Jones and Jönsson 1994). With Premium you log a meal, and the drinks after it are absorbed more slowly in the estimate too. It only ever works in that direction: a meal logged after drinking does not lower the number, and the rate your body clears alcohol stays at its empty-stomach value. Food is also the least precise part of any BAC model.

Legal limits and safety

Does the app tell me whether I am safe to drive?

Never. Alcophone shows a number and the limit that applies where you are; it does not give permission. Impairment starts below every legal limit in the world, and an estimate is not a measurement. The design deliberately pairs the number with a way to get home instead of a verdict.

What is the legal limit where I live?

It depends on the country and often on the state or province. Full tables are on this site for the United States, Canada, Australia, the United Kingdom, India and Ireland. The app applies the right one automatically once you set your region.

What about new drivers?

In several countries the limit for learner and provisional drivers is zero, not the adult limit. Alcophone knows this and applies it when you tell it your licence type. The details are in our guide on zero tolerance for new drivers.

Privacy and data

What data does Alcophone collect?

Your drink log, BAC history and body details stay on your phone: we never receive them, and there is no account to create. The app does use Google services: usage statistics and crash reports (both can be switched off in Settings), ads in the free version, and Google Play for purchases. The full detail is in the privacy policy, and everything can be erased from the app or through the data deletion page.

Can I get my drink history out of the app?

Yes, with Premium. Export your drink history as CSV, or save a full backup and restore it on another device.

Buying Premium

Can I try Premium before buying?

Yes. You can start a 14-day free trial inside the app. No payment details are needed, and when the trial ends the app goes back to the free version. Nothing is charged.

How much does Premium cost?

Premium is a one-time purchase on Google Play: $9.99. Outside the USA, Google Play shows the price in your local currency. There is no subscription.

I got a new phone. Do I have to pay again?

No. Premium is tied to your Google account. Install Alcophone with the same account and Premium comes back automatically, or tap Restore Purchase in Settings. Your drink history lives only on your phone, so move it with the Premium backup, or take it along as a CSV export.

Can I get a refund?

Purchases and refunds go through Google Play. Open your Google Play order history, choose the Alcophone purchase and ask for a refund there. If Google refers you to us, email safemetrics4u@protonmail.com with your order number (it starts with GPA.). This does not affect your rights under the consumer law of your country.