The holiday season is here, and that means plenty of eating and drinking. Nothing wrong with that, if you ask me. But there is something wrong with driving while drunk. It is illegal in many countries, and it is definitely dangerous and irresponsible everywhere. But how much drinking is too much? How do you know when you should let someone else drive?

DrinkOrDrive, a mobile app for Nokia touchscreen phones, can help. Based on your size, weight and what you’ve recently had to eat and drink, the app gives you a graphical Drive/Don’t Drive rating. If you merit a Don’t Drive warning, the app also tells you how long you should wait before driving.

When you launch DrinkOrDrive, you first select metric or imperial measures, and then enter your weight, height and sex. Next, you select the Drink menu to record your drink’s capacity, drink type (beer, liqueur, wine, etc.), and time — now, X minutes ago (where you enter a value for X), or a specific time.

Next, you select the Eat menu. A person eating can drink more and feel it less than a person with an empty stomach. So here you complete two fields: Measure, which indicates whether you’ve eaten a small, normal, or big meal. And Time, which indicates how recently you’ve eaten.

The DrinkOrDrive app takes all that data and produces the following screen graphic. Using my test data as an example, the app says I should not drive. It also says I should wait 2 hours, 34 minutes — that is, until 11:45 — before driving:

The triangle represents your blood sugar, and the notches represent 15-minute increments. The up and down arrows let you zoom in and out. The left and right arrows let you see portions of the chart that may be obscured when you’ve zoomed in very far. All the other buttons, as far as I can tell, simply take you back to the main menu.

A number of other settings are offered, too. History (found under Drink) shows you what you’ve recently entered; it could come in handy after a long night of celebrations:

The Capacities menu (under Settings) lets you indicate the size of your drinks in millilitres. The Other menu (also under Settings) lets you define the maximum allowable blood alcohol level (in parts per thousand). The Advanced menu (again, under Settings) lets you define the default alcohol loss. If I understand this correctly, it shows how much time needs to pass for your blood alcohol to decrease by 5 per cent:

While DrinkOrDrive works fine (as tested on my Nokia N97), you should still exercise caution and be careful. This app is simply an aid. It does not provide legal or medical advice. At best, DrinkOrDrive should encourage you to think carefully about driving after drinking. Used properly, it could even save a few lives.

DrinkOrDrive has been created by Hungarian developer Web ITem Ltd., and it costs $4.99 in Ovi Store. For more information, check out the developer’s DrinkOrDrive site.

And remember — with or without your mobile device — if you’ve had too much to drink, don’t drive.

Have a Happy – and Safe – New Year!