How much caffeine is in Barq's Root Beer?

A 12 fl oz can of Barq's Root Beer has 22 mg of caffeine.

That's about a quarter of a cup of brewed coffee, and 6% of the 400 mg a day the FDA cites for most healthy adults.

Source: Center for Science in the Public Interest · checked 10 Nov 2026

When did you have it?

Had at 3 pm, about 7.7 mg is still in you at an 11 pm bedtime. That should not affect most people’s sleep.

Bedtime

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Latest time to drink it

For an 11 pm bedtime, a 12 fl oz can of Barq's Root Beer stays under the 50 mg most people sleep fine with, even late in the evening. The table works it out for other bedtimes and for how sensitive you are: it is the latest time to start one so that the caffeine left stays under the line all night.

Bedtime	Very sensitive under 25 mg	Average under 50 mg	Not very sensitive under 100 mg
9 pm	Any time	Any time	Any time
10 pm	Any time	Any time	Any time
11 pm	Any time	Any time	Any time
Midnight	Any time	Any time	Any time
1 am	Any time	Any time	Any time

For a 12 fl oz can of Barq's Root Beer, average clearance (half-life 5 h), 8 hours of sleep. "Any time" means even one at bedtime stays under the line.

How long it lasts

The caffeine from a 12 fl oz can of Barq's Root Beer peaks in your blood about 75 minutes after you start it, at roughly 19 mg. Half of it is gone in about 5 hours for an average adult; that ranges from roughly 3 to 7 hours, and longer in pregnancy or with some medicines.

Time after	3 hours	6 hours	9 hours	12 hours
Still in you	15 mg	10 mg	6.7 mg	4.4 mg

So one had at 3 pm leaves about 7.7 mg at 11 pm. How long caffeine lasts explains the curve.

How it compares

Barq's Root Beer is stronger than 7% of the 15 sodas we track, by caffeine per serving.

Per fluid ounce (1.8 mg) it is stronger than 7% of them.

To reach 400 mg in a day you would need about 18 of these.

Less caffeine

Sunkist Orange Soda 19 mg, 12 fl oz can
Caffeine-Free Coca-Cola no caffeine
Fanta Orange no caffeine

More caffeine

Coca-Cola 34 mg, 12 fl oz can
Poppi Cola 40 mg, 12 fl oz can
Dr Pepper 41 mg, 12 fl oz can

FAQ

Is Barq's Root Beer high in caffeine?

No, it is low. A 12 fl oz can of Barq's Root Beer has 22 mg, which is 23% of the 95 mg in an 8 fl oz cup of brewed coffee.

Can I drink Barq's Root Beer at night?

For most people, yes: even late in the evening a 12 fl oz can of Barq's Root Beer stays under 50 mg at an 11 pm bedtime.

How long does the caffeine in Barq's Root Beer last?

It peaks about 75 minutes after you start it. Of the 22 mg, about 10 mg is still in you 6 hours later and 4.4 mg after 12 hours, for an average adult with a 5-hour half-life.

Does Barq's Root Beer have more caffeine than a cup of coffee?

No. A 12 fl oz can of Barq's Root Beer has 22 mg; an 8 fl oz cup of coffee has 95 mg.

Method and limits

The caffeine figure comes from Center for Science in the Public Interest; recipes, brewing and batches vary, so a real serving can differ. The curves use a standard one-compartment model with an average 5-hour half-life and a sleep-friendly line of 50 mg; your own body may clear caffeine faster or slower. How it works has the details.

These are estimates for information, not medical advice.

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