Drinking and Driving is dangerous. You will get into big trouble If you drink and drive. You can check Blood Alcohol Concentration (BAC) using a regular Breathalyzer or Breath Alcohol Detector. If you are looking for an android or iOS app to check blood alcohol level, You are in luck.
You can buy regular Breathalyzer like BACtrack Select S80 Breathalyzer for about $130 or BACtrack Keychain Breathalyzer for $30 on Amazon. These are portable and mostly show accurate BAC levels.
How to check Blood Alcohol Level on iPhone or android like Galaxy S3, S4, Note 2 etc
Breathometer has small, portable Breathalyzer that can be attached to iPhone or android phone via headphone jack. You can buy it for $20 and get it in January 2014. You can pay $100 now to get it in Summer 2013.
You will need to download the app. Just blow into the device to get your BAC level. You can decide to drive or wait depending on Blood Alcohol Level. You can track your activity history with the app as well.
2. AlcoDroid Alcohol Tracker
AlcoDroid Alcohol Tracker android app lets you enter your drink intakes and calculate BAC level. It shows an estimate for BAC. You can also log your daily or weekly drinking intakes and chart them. It does not seem to be accurate. It is just for informational purposes.
3. Blood Alcohol Content calculators
You can find many Blood Alcohol Content calculators online including this one from University of Oklahoma Police dept. You can access it on android phone or iPhone. You can enter the number drinks you took, number of hours you are drinking, type of drink including Beer, Light Beer etc. It displays BAC %. All states have 0.08% BAC as legal limit as per this site.
You can use these methods most smart phones including iPhone 5, iPhone 4S, Galaxy S3, S4, Note 2, HTC One, Sony Xperia Z, Nexus 4 etc.
Also read, How to find your lost Samsung android phone