5 Best Diet Root Beer | The Diet Soda That Tastes Real

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The zero-sugar root beer that dupes even die-hard regular drinkers.

You want a diet soda that tastes so close to the full-sugar version that people in your house might not notice. This is the one. A&W Zero is sweetened with the same creamy vanilla profile as original A&W. Buyers confirm that “this root beer tastes like regular root beer, not diet.” It’s the biggest total package here at 320 fluid ounces across 16 bottles. The 11 x 11 x 11-inch box weighs 22.55 pounds — a 49% heavier load than the A&W Diet can pack — so you will need a sturdy lower shelf.

Reviewers consistently love the flavor but note that “it’s a little pricey.” The trade-off is clear: you pay more per bottle for a premium taste that doesn’t scream “diet.” A&W Zero delivers the creamiest mouthfeel of any zero-sugar option here. Because it comes in resealable bottles instead of cans, you can pour a half-glass without wasting the rest. One reviewer summed it up: “Great value. Everyone loves it.”

Unlike the Barq’s line where Zero loses the signature bite, A&W Zero keeps the full creamy body. The one real catch: there is no sugar-free float potential if you are avoiding carbs — though a buyer did mention pairing a different brand with ice cream. Still, for straight-up sipping, this is the taste champion.

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The only diet root beer that still bites back.

Barq’s has a flavor that stands apart from the creamy crowd: a sharper, more carbonated “bite.” That comes from a higher caffeine content (about 22 mg per 12-ounce can) and a snappier sassafras (root beer spice) profile. The Diet version keeps that signature sharpness intact, delivering 288 fluid ounces across 24 cans — that is 33% more cans than A&W Diet’s 18-pack. Buyers report the distinction clearly: “Same ingredients but different taste; Barq’s classic bite missing in Zero, making it sweeter.” If you buy Barq’s, make sure you grab the Diet label and not the Zero, or you lose the very thing you came for.

Reader reviews are short and loyal — “best dam root beer,” “great root beer and great delivery.” But one 4-star fan admits “it’s not as good as diet Bargs,” which really says the same thing twice: Barq’s drinkers are picky, and this Diet can delivers the exact experience they expect. The 24-can flat fits neatly into pantry rotation without the weight of the bottle-based options. There is no vanilla creaminess here — this is a crisp, spicy root beer that stands up to ice cream without getting lost.

One thing sets this apart from Zevia and Shasta: Barq’s Diet uses aspartame, not stevia or Splenda. If you are sensitive to aspartame’s aftertaste, you may prefer a sweeter alternative. But if you grew up on Barq’s and refuse to switch, the Diet version is your lifeline to zero sugar.

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The stevia-sweetened root beer that converts aspartame skeptics.

Zevia takes a completely different route: it uses stevia leaf extract (a plant-based sweetener) instead of artificial sweeteners. It is Non-GMO Project Certified, vegan, gluten-free, and clear in color. That crisp look may be a surprise if you are used to root beer’s caramel brown, but the “Creamy Root Beer” flavor aims for a smooth, dessert-like experience. Owners mention “sweet but addictive natural zero-calorie soda” and one called it “like a drug” — once you acquire the stevia taste, it is hard to go back.

The 20-can pack delivers 240 fluid ounces, which sits between the smaller A&W Diet 18-pack (216 fl oz) and the bigger Barq’s 24-pack (288 fl oz). I’m so upset I can’t afford it anymore!” The price has climbed significantly, making Zevia less of a budget daily-drinker and more of a premium treat. Still, if you react poorly to aspartame (one Shasta reviewer specifically praises “no aspartame side effects”), Zevia is the only stevia-based option in this roundup.

Several reviewers admit the first can tastes “very different.” Stevia has a distinct lingering sweetness that some people love and others bounce off. Stick through a can or two, and “it’ll become your favorite drink,” one fan promises. The can labels reportedly rub off easily, but the soda inside stays intact. For a creamy root beer float, Zevia’s clear liquid and creamy taste profile work well with vanilla ice cream.

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The biggest 24-can pack that sweetens with Splenda, not aspartame.

Shasta Diet Root Beer stands out for two reasons: it uses Splenda (sucralose, a heat-stable sweetener) instead of aspartame, and it packs 24 cans for the same 288 fluid ounces as Barq’s Diet. One buyer raves: “Diet Shasta Root Beer: great taste, no aspartame side effects, doesn’t raise blood sugar, hard to find locally, convenient on Amazon.” Another confirms “I can enjoy root beer with splenda flavor instead of aspartame.” If you get headaches or bloating from diet sodas, Shasta might be the answer.

The brand leans toward a lighter, crisper root beer flavor compared to A&W’s creamy weight. It is not as sharp as Barq’s and not as rich as Zevia, but it hits a middle ground that most palates will find pleasant. “Holy moly, Batman, this is the best TASTING root beer ever!” one fan says. The 16.4 x 10.7 x 5-inch package is a bit wider than the A&W Diet 18-pack but still manageable. Since Shasta offers over 30 flavors, you can mix and match, but this review is strictly for the Diet Root Beer.

The biggest downside: Shasta is a smaller brand than A&W or Barq’s, so local store availability is spotty. That is exactly why Amazon is the move here — you get the 24-count without hunting. For the budget-conscious shopper who wants to avoid artificial sweeteners and still get 24 cans, Shasta is the best per-can value in this list.