Short answer: A 12 fl oz can of Bare Brew lists 0g sugar, 20 calories and 5g total carbohydrate. Plain black coffee you brew at home is listed by the USDA at 0g carbohydrate per cup. So if you're asking for the lowest-carb coffee you can drink, the honest answer isn't our can. It's a mug of black coffee you made yourself. This page runs the label math so you can decide whether 5g fits your day. We won't make that call for you.
Why this page changed
This article used to be titled "Cold Brew on Keto: Why It's the Perfect Low-Carb Coffee." That headline overstated things. Our can isn't zero-carb, "perfect" isn't a number, and whether a drink fits a ketogenic diet depends on the rest of your day, not on the can. The old version also gave a steep time we can't source to any primary document, so we took it out. What's left is what we can show: the numbers on our label, the numbers on the USDA's, and the definition dietitians actually use.
What "keto" means in grams
"Keto" gets used loosely on labels, so start with a definition. The Alberta Health Services nutrition guideline on restricted-carbohydrate diets (reformatted September 2025) defines a ketogenic diet as 20 to 50 grams of carbohydrate a day, or less than 10% of total energy from carbohydrate. It notes that the figure refers to available, or net, carbohydrate: total carbohydrate minus dietary fibre.
The same guideline makes a few points that rarely appear on brand blogs:
- It recommends that people following a ketogenic diet be medically monitored.
- In people with diabetes, restricting carbohydrate can raise the risk of low blood sugar if diabetes medications aren't adjusted, and it flags SGLT-2 inhibitors as a specific concern.
- It states ketogenic diets aren't recommended during pregnancy.
If any of that applies to you, the person to ask is your prescriber or a registered dietitian, not a coffee company.
The label math
Here's what a can of Bare Brew and a few common keto-coffee setups add up to against the low and high ends of that 20 to 50g range. Bare Brew figures come from our own nutrition label. Coffee and cream figures come from USDA FoodData Central.
| What you drink | Carbohydrate | Calories | Share of a 20g day | Share of a 50g day |
|---|---|---|---|---|
| Home-brewed black coffee, 8 fl oz (USDA) | 0g | about 2 | 0% | 0% |
| Black coffee + 2 tbsp heavy cream (USDA) | under 1g | about 100 | under 5% | under 2% |
| 1 can Bare Brew, 12 fl oz (label) | 5g total | 20 | 25% | 10% |
| 2 cans Bare Brew (label) | 10g total | 40 | 50% | 20% |
Three things stand out.
Plain black coffee wins on carbs. If carbohydrate is the only thing you're optimizing, home-brewed black coffee beats our can. We'd rather say that here than have you find it out from a macro app.
One can is a real line item on a strict day. At 20g a day, one can of Bare Brew uses a quarter of your budget. At 50g it's a tenth. Two cans in a day is half of a strict budget. Whether that trade is worth it depends on what else you eat. We aren't the right people to decide that for you.
Cream isn't the carb problem people think it is. Two tablespoons of heavy cream add about 100 calories but under a gram of carbohydrate, per USDA data. If you're counting calories as well as carbs, the cream matters. If you're only counting carbs, it barely registers.
Total carbs vs net carbs
Our label lists total carbohydrate: 5g. Many keto plans, including the Alberta Health Services definition above, count net carbohydrate, which is total minus dietary fibre. If your plan counts net carbs, read the fibre line on the nutrition panel and do the subtraction yourself. We aren't going to print a net-carb number in marketing copy. That's how "zero-carb" claims end up on cans that aren't.
Zero sugar is not zero carbs
This is the mistake we see most often, and we used to make it on our own site. Bare Brew has 0g sugar. That's the lead claim on the can, and it's accurate. It also has 5g total carbohydrate. Those two facts aren't in conflict. Sugar is one kind of carbohydrate, and a drink can list zero of one and a few grams of the other.
The same goes for ingredient counts. Bare Brew has two ingredients: coffee and water. A short ingredient list tells you what's in the can. It doesn't tell you the macro numbers. For those, read the nutrition panel. We wrote a longer piece on what "zero sugar" and "sugar-free" mean on coffee labels if you want the regulatory definitions.
What 0g sugar does mean is simple. There's no added sugar, so there's no sugar spike from the can. We're not making a claim about how you'll feel. We're telling you what isn't in it.
What to check on any "keto" coffee label
Plenty of canned coffees put "keto" on the front. Here's the four-line check we'd run on any of them, ours included:
- Total carbohydrate, per container, not per serving. Some cans list two servings. Multiply.
- Sugar and added sugar. These are separate lines on the US Nutrition Facts panel. "No added sugar" and "0g sugar" aren't the same claim.
- Sweeteners. Sucralose, acesulfame-K and similar non-nutritive sweeteners contribute essentially no carbohydrate. Research on how they affect insulin response in different people is still ongoing and unsettled, so treat any strong claim either way with caution.
- "Natural flavors." Under FDA rules (21 CFR 101.22), "natural flavor" covers flavoring constituents drawn from a wide range of plant and animal sources. The label won't tell you which ones. If you need to know exactly what's in the can, a short ingredient list is easier to check.
We did this exercise against real published labels in what's actually in your canned cold brew. Every figure there comes from a printed label, not a lab.
Fasting: we're leaving that call to you
Many people who eat keto also fast, and the most common question we get is whether a can "breaks" a fast. Here's what we can tell you. The label lists 20 calories and 5g total carbohydrate per can. Whether that fits your fasting window depends on the protocol you follow, and protocols disagree. Some allow a small number of calories and some allow none. If you're fasting under medical supervision, ask the person supervising. We cover the different protocol definitions in does cold brew break a fast.
The caffeine number matters more than the carb number
For most people reading this, 5g of carbohydrate isn't what deserves attention. 320mg of caffeine is. The FDA cites 400mg a day as an amount not generally associated with negative effects for most healthy adults. One can of Bare Brew is 80% of that figure. If you also drink a pot of coffee at home, or take a pre-workout with caffeine in it, add them up. Sensitivity varies a lot from person to person. If you're pregnant, breastfeeding, sensitive to caffeine or on medication, ask your health care provider first.
We broke down what 320mg means against other drinks in our caffeine content page, including where other brands are more concentrated.
What cold brewing changes, and what it doesn't
Cold brewing changes extraction, not macros. A 2018 study in Scientific Reports (Rao and Fuller) found cold brew had lower total titratable acidity than hot brew from the same beans at comparable pH. The study doesn't support a percentage, so we don't quote one. (We explain why we don't quote an acidity percentage.) None of that changes the carbohydrate number. Cold or hot, plain brewed coffee is listed at essentially zero, and our can is listed at 5g.
If 0g sugar, two ingredients and 5g total carbohydrate per can fit your numbers, here's the 12 oz can. It's $4.50 a can in a 12-pack, and shipping is $8.99 flat on every US order.
Founder's Take
This page used to say our can was the "perfect" low-carb coffee. I took that down. Our label says 5g of carbohydrate, and on a 20g day that's a quarter of your budget. That's a lot to wave away with an adjective.
Here's what I'll stand behind. There's no sugar in it. There are two ingredients, and you can read them in two seconds. Every number on this page matches the label. If you're strict keto and carbs are the only thing you're counting, brew black coffee at home. It's lower-carb than my can, and I'd rather you hear that from me. If you want 320mg in a can with nothing added, that's what we make. Just count it. — Miles, founder
Frequently asked questions
Is Bare Brew keto?
We don't label it keto. A 12 fl oz can lists 0g sugar, 20 calories and 5g total carbohydrate. Against the 20 to 50g daily range Alberta Health Services uses to define a ketogenic diet, one can is 10% to 25% of the day. Whether that fits your plan is your call, ideally with your dietitian or doctor.
How many carbs are in a can of Bare Brew?
5g total carbohydrate per 12 fl oz can, with 0g sugar and 20 calories.
Is plain black coffee lower in carbs than Bare Brew?
Yes. USDA FoodData Central lists brewed black coffee at 0g carbohydrate per 8 fl oz cup. Bare Brew lists 5g per 12 fl oz can.
Does Bare Brew break a fast?
That depends on your fasting protocol. The can lists 20 calories and 5g total carbohydrate. Some protocols allow a small number of calories and some allow none. Check yours, and ask your doctor if you're fasting under medical supervision.
Does zero sugar mean zero carbs?
No. Sugar is one type of carbohydrate. Bare Brew lists 0g sugar and 5g total carbohydrate. Both numbers are on the label.
How much caffeine is in a can?
320mg in 12 fl oz. That's 80% of the 400mg daily amount the FDA cites for most healthy adults.
Related reading: coffee and blood sugar: what the research says, does caffeine raise blood sugar? the dose math per can, and zero sugar cold brew explained.
