Picture this: You're out with some friends.

You're having a great time.
You've been drinking.

It's time to go home and some of your friends are doubtful if you're okay to drive. You're even doubtful if you're okay to drive. You don't have a pocket breathalyzer and you're certainly not going to call the cops. How do you decide to drive or hitch a ride?

Well, if you have an iPhone or iPod Touch, “there's an app for that!”

Check out these useful utilities you can download to make sure you stay safe and sober on the road.

drunkulator – $0.99
Check your BAC on the go. This application uses both standard and metric systems. This easy to use interface has big buttons, but is very basic. The calculation is based on the assumption all of your drinks have relatively similar alcohol content. The BAC is based on your inputs and tells you if you're tipsy, drunk or had too much. Since we tend to be more gracious with our own pours, this application may not be too useful if you've been mixing your own drinks.

BAC reader – $0.99
This application is similar to the drunkulator, but the BAC reader takes into account the difference between liquor, wine and beer. The simple click wheel interface gives an approximate BAC based on these inputs. However, if the user is not aware of local drunk driving laws, or what is considered safe, the number is useless as the program gives no guide once calculated.

BAC calculator iDrinkSmart, scientific – $0.99
The iDrinkSmart is a comprehensive analysis of factors that would affect your BAC, such as weight, gender age and recent food consumption. Developed by scientists, the application is as accurate as possible, and the best of class for applications less than a buck.

The application is much more interactive, allowing the user to adjust the level of alcohol concentration per drink, whether wine, beer or liquor. Users can even estimate the approximate length of time until sobriety (no alcohol in your system). Unfortunately, most people don't know content levels offhand, and the likelihood of asking the bartender is minimal. Although iDrinkSmart looks very nice and is comprehensive, is might be complicated for a truly drunk person to navigate.

Got Your BAC – $1.99
Slightly more elaborate than your basic drink calculator, Got Your BAC allows you to calculate by picking the drinks you've had from a drink menu that includes many popular mixed drinks. The interface also calculates calorie and carb intake, quite handy for the drinker who's watching their figure. As you add drinks to the list throughout the night to the “slosh-o-meter,” Got Your BAC keeps track of your estimated BAC level. When you've reached your limit, a button appears that when pressed, will find and call a local taxi company to take you home safely. This app also supports multiple profiles so that you can keep track of not only you, but also your friends.

Cheers! – $2.99
This time efficient application keeps real time data of your estimated BAC based on the standard scientific formula. Like Got your BAC, it can find you a taxi when the program decides you've had too much. However, to get completely accurate results you have to input in each drink as at the time of consumption. Since the formula relies partially on consumption and your body's absorption of alcohol, not remembering to put in data in a timely fashion can result in inaccurate results.

miniBAC – Free
This is a good, simplistic calculator that can be used after the fact. Input your weight, gender, number of drinks, and hours you've been drinking and it will give you a rough estimate of your BAC. It's probably not the most accurate tool, but it has large buttons and is easy to navigate and read even while intoxicated. The application also includes brief descriptions of what kind of effects you should be experiencing based on your BAC. Not bad for a free app, though not extremely scientific either.

Other Useful Drunk Apps

drunkdialNO! – Free for a limited time – $0.99
We all have that person we shouldn't talk to, but when we get a little tipsy, all rationality flies out the window. drunkdialNO! looks out for you; On your way out to party, you decide who you shouldn't be calling and drunkdialNO! will erase these numbers from your contacts for a designated period of time. You pick how long each contact will remain missing from your phone and avoid embarrassing morning after situations.

Designated Dialer – $0.99
This is similar to drunkdialNO! except all contacts are locked for the same period of time. Although their numbers still appear in your phone, when you try to call them you will instead be routed to a toll-free number with a friendly reminder message indicating you probably shouldn't be calling this person. Your contacts will remain locked until you run the application again and pass a simple coordination test indicating to the program that you are sober enough to make responsible phone decisions again.

These are just a few of the cool applications available in the iTunes store.

A word of caution: you will also find breathalyzer applications in the store. DO NOT DOWNLOAD A BREATHALIZER APPLICATION. They are all programmed as gags since an iPhone cannot actually act as a breathalyzer. Maybe in the future Apple will make that possible, but for now all breathalyzer apps deliver pre-programmed outcomes for a laugh.

Finally, a quick note. Though they can be extremely helpful in keeping you safe, these applications are not exact scientific measures of BAC and cannot be used as a defense against DUI laws. While they can be good personal guides, they are provided for entertainment purposes only. Don't rely on a phone application to keep you safe. Know your limits and please drink responsibly.