What’s Really in Your Cup? A Caffeine Mythbusting Guide

This myth has been making the rounds in cafés and comment sections for years. But the truth is, caffeine content doesn’t vary much between roast levels—it’s virtually the same by weight across all coffees.

But what does vary? Density.

Lighter roasts are denser and take up less space by volume. If you measure with a scoop instead of weighing it with a scale, you’ll pack more coffee (and therefore more caffeine) into your brewer.

Dark roast beans are roasted longer, which causes them to puff up and lose moisture. This lower density means that you’re using less coffee per scoop and getting a weaker cup as a result. The caffeine hasn’t gone anywhere—it’s just spread thinner.

So no, light roast won’t keep you up all night any more than a dark roast will. The amount of caffeine depends on how much coffee you’re using, not the roast level.

Caffeine levels are most accurately controlled by measuring coffee by weight rather than volume. A level scoop of light roast may weigh 7 grams, whereas the same scoop of dark roast may only contain 5 grams.

When dialing in your caffeine, here’s what matters:

• Coffee species: Arabica beans clock in caffeine in the 1% range by weight, while Robusta beans are in the higher 2% range—almost double! They also taste more bitter, because caffeine itself is bitter.

• Grind size: Finer grinds typically extract more caffeine because more of the surface area is exposed to water, though this amount depends on the brew method (espresso vs. drip vs. French press).

• Temperature: Hot water extracts caffeine more quickly than cold water. However, since cold brew steeps longer and often uses more coffee, it can match—or even exceed—the caffeine in hot coffee. Some think that caffeine from cold beverages hits you faster, but there’s no clear evidence for this.

• Serving size: The size of your brew matters. A double espresso has more caffeine than a single, and a 16-oz pour-over will almost always top them both.

Bottom line: Roast level and brew method matter far more for flavor than for caffeine. The buzz in a cup of coffee comes down to simple math—how much ground coffee you use and how much water you brew it with. And that leads us straight to the next (and most important) factor.

Want more caffeine in a cup? Use more coffee. Need less? Use less coffee.

This is known as your brew ratio—the proportion of water to coffee—and it’s the single biggest factor that determines caffeine content.

A good starting point is an 18:1 ratio (grams of water to grams of coffee) and adjust from there. Some roasts shine at different ratios; for instance, light roasts often taste brighter and more complex at lower ratios like 16:1—or even 12:1 if you’re feeling bold. Discovering the perfect balance is half the fun of brewing.

Once you've dialed it in, consider adding clear brewing instructions to your packaging. It helps customers both brew a good cup of coffee and manage their caffeine intake.

Most healthy adults can safely consume up to 400 milligrams a day, which is roughly three to four cups of coffee.

The amount of caffeine in your cup depends heavily on serving size. Here's what ranges you're likely getting, according to a study on caffeine consumption.

• 8 oz cup of coffee: 63-126 mg caffeine

• 12 oz cup of coffee: 95-190 mg caffeine

• 16 oz cup of coffee: 126-253 mg caffeine

• 20 oz cup of coffee: 158-316 mg caffeine

• Single shot of espresso (1 oz): ~63 mg caffeine

• Double espresso shots (2 oz): ~126 mg caffeine

How Coffee Stacks Up: A 12 oz coffee packs way more punch than other caffeinated drinks like green tea (37 mg), black tea (71 mg), and some energy drinks. As we’ve said, the amount of coffee beans used matters more than roast level.

Know Your Limits: Most coffee shops serve 16-20 oz as standard sizes, meaning one large coffee could deliver 126-316 mg of caffeine—potentially up to the daily limit. While 400 mg is the general guideline, individual sensitivity varies—some may feel effects like increased heart rate and jitters at lower levels. To decrease caffeine intake, recommend your coffee drinkers try a smaller size, order decaf, or request "half-calf" coffee.

Communicate clearly: The FDA doesn't require coffee roasters to list caffeine content on packaging. If you do include caffeine information/levels on your bag, it’s important to communicate clearly and not mislead the average consumer. For example, don't add a "caffeine-free" label to a bag of decaf coffee, since all decaffeination processes leave trace amounts of caffeine behind.

While roast level gets most of the attention in caffeine debates, it’s far from the only misconception brewing in coffee culture.

Some myths have been passed around for decades, shaping how people store, brew, and even judge their coffee. Let’s set the record straight with these truths:

• Caffeine doesn’t “roast away.” Caffeine is incredibly stable under heat. Standard roasting temperatures aren’t nearly high enough to destroy meaningful amounts, so whether your beans are light or dark, the caffeine stays put.

• It doesn’t vanish in storage. Stale beans may lose flavor and aroma, but their caffeine content remains intact. To keep your coffee fresh for longer, choose packaging with quality barrier protection—our specialty.

• Decaf coffee is a worthy alternative. Modern processing has improved dramatically— meaning that a good decaf will earn a following.

There’s a lot of nuance in the coffee world, but when it comes to caffeine, the facts are refreshingly simple. Thanks again to Mike of Firedancer Coffee Educators for cutting through the confusion.

In the meantime, don’t let your beans go stale. Store them in high-quality coffee packaging that locks in freshness for peak flavor. Your taste buds and your customers will thank you.