I know sometimes it surprises me how strongly one cocktail can affect me versus another, especially if the "strength" seems switched. A lot of people have mis-judged their tolerance but it's not always just the ingredients in a mixed drink recipe that determine how strong it is. When it comes to the many different types of mixed drinks out there, you need to understand that while the amount of alcohol has a lot to do with the overall strength of a drink - there are several other factors that can explain why one drink can affect you so strongly even if it supposedly is "less strong" than another one that you can handle more easily.
Proof of the liquor
This isn't to be mistaken with the overall strength of the mixed drink, but the two do tend to be strongly related. The proof of the liquor is interesting because it's important to notice that while whiskey, tequila, rum, and vodka are all grouped together under the general term of "hard liquor," these can have drastically different one another when it comes to overall proof. For example, many types of vodka will actually be a lower proof than some common mixing whiskey or rums.
This can be even more confusing when you have "over proof" liquors - which is especially common with the rum. Bacardi 151 is a common popular example, as it brags about having almost double the common proof of your normal rum. Obviously the extra proof there is going to make any rum based drink a lot stronger than even some other drinks that have more shots in them. The proof definitely matters - especially when putting together a cocktail that will knock the biggest drinker off of his stool.
Strength of the recipe
While this is often compared hand in hand along with the proof of the liquors being mixed in, it still deserves its own attention. A recipe calling for five shots of hard liquor or four shots with some extra (hello Long Island Iced Tea!) lower level liquors on the side will generally be much stronger than something simple like a normal whiskey and coke or Seagram's and 7-Up. A fuzzy navel that focuses on peach schnapps just isn't going to kick the way a much harder liquor will. Of course this is all assuming that the drink is mixed with exact measurements in the bartender's guide. Which brings up our next factor that affects the strength of your favorite drinks....
General rule of thumb for well over 90% of bar partrons: when they say the bartender is "good" or "mixes them good" or "takes care of you" they mean the bartender mixes the drinks a whole heck of a lot stronger than what the recipe calls for. In theory, the girly drink of a fuzzy navel can be stronger than a whiskey and coke if 80% of a tall glass is peach schnapps while a whiskey and coke is mixed with only one shot of whiskey. If one bartender mixes them very strong and another mixes the drinks weak, then obviously the strong mixes will be the stronger drinks. This can definitely trump the book recipe to make "weaker cocktails" stronger in reality than the mixed drink recipes calling for higher proof liquor. The level of mixing matters big time.
Carbonation, caffeine & sugars
I know one of the major factors I often overlook when judging how strong a drink is carbonation are the mixers. Why? Carbonation in a mixed drink means the alcohol will hit your system much faster. Add in the energy surge and crashes that come from sugar, or the insanity that can result with energy drink levels of caffeine added in with alcohol and you can see how it doesn't just take alcohol to make a strong mixed drink. That carbonation, sugar high, caffeine surge - or all of the above - can make for a drink that doesn't need nearly as much alcohol in order to really back a crazy punch. Be sure to pay close attention to those mixers to keep yourself in the game - especially if you need to pace yourself all night.
Speed of drink - "Bombs"
How quickly you drink goes a long way to packing a punch. However oddly enough many people don't think about that with "bomb" based drinks that call for a guzzling of the drink. Irish Car Bombs, Jager Bombs, and Vegas Bombs. You might think a glass of beer or shots of Bailey's don't add up to much - but mix it and guzzle it, and you'll be feeling it very quickly. Not advised when you're already near your limit.
There are many different reasons a drink can be labeled "strong." Hopefully by reading this article you'll not only pay attention to proof and strength of recipe, but you'll look at ALL of the factors that go into making these mixed drinks strong enough to challenge any tolerance level.