I’m a dude that owns a cocktail shaker but I’ve never worked at a bar in any capacity.

This one doesn’t seem to have a concrete answer because there’s a big bouncing blue billion ways to make a margarita.

The IBA recipe for a margarita calls for 50mL blanco tequila, 20mL triple sec, 15mL lime juice. Shake with ice, and then strain into a chilled cocktail glass, with an optional half-salted rim. I’m not much of a margarita guy but I’ve personally never seen one served up, they’re usually served on the rocks. Or “frozen.”

If you were to ask me to make you a frozen margarita, I’d try to talk you out of it, and then I’d probably dump everything I’d put in the shaker in my food blender, possibly also with the rocks I’d have served it over, ground it until it stopped grunching and then poured it in the glass, and I bet you wouldn’t enjoy it much.

I’m basically going to jump over “buy a jug of tequila mix from the grocery store and just add tequila.” I don’t know what’s in that and I don’t really care.

I cannot find a recipe for a single frozen margarita; most recipes are for making batches of 4 cocktails at a time or so, often adding simple syrup or agave nectar, dosing the liquid ingredients in terms of cups rather than ounces or milliliters. These recipes I’m reading are intended for amateurs to make at home in a blender. A nicer cocktail bar will likely do something like that, rev up a blender for you. A lot of places will have a slushy machine with batches made by the gallon. What they load it with? depends on the establishment. Might be off the shelf margarita mix and tequila, might be whatever mix they get from Applebee’s corporate, might be their own in-house “Joe’s Signature Recipe” whatever…

BOIL IT DOWN, FISTFUCKER

If you’re in the kind of place where you order a frozen margarita and the bartender makes it in a blender for you, I think you’re going to get the same amount of booze either way, approximately equivalent to 1.5 to 2 shots of tequila*. The variables are how quickly you’re going to drink it, and how much water you’re going to swallow alongside. If served up, you’ll likely drink it faster and with the least accompanying water. On the rocks will slow you down slightly and a little more water will melt into the drink while you’ve got it; most people will finish the drink before the ice completely melts and not eat the remaining ice. A frozen margarita will have ~ as much ice as a margarita on the rocks but you’re going to swallow it all(I say swallow because do you eat or drink ice/liquid slush?)

In an establishment that has a margarita slushy machine, they’ll obviously serve you a goblet of…whatever that is. I imagine it will be dosed so that the serving you get will have about the amount of booze in it will have. If you ordered a margarita up or on the rocks, are they going to measure tequila, triple sec and lime juice, or give you tequila and their margarita mix…? Go to enough bars and the answer will average out to “yes.”

I think the bottom line is going to be, “drinks” are mostly dosed for about the same amount of alcohol. The amount of water, sugar etc. and how fast it is consumed is what makes any practical difference. I see people talking about which is more “watered down.” Imagine this: You take two shots of tequila, then one shot of water. OR, you take two shots of tequila, then two shots of water. In which scenario did you drink the most tequila?

*I’m in the US, I define a “shot” as 1.5 ounces or ~45mL, and both Tequila and triple sec vary in ABV, figure typical spirits or liqueurs are ~40% ABV of 80 proof, give or take the metric system.