A Caffeine Calculator
We all know coffee contains caffeine – but how much of that caffeine makes its way from the coffee bean into our brewed beverage?
Understanding your caffeine intake can be helpful if you're looking to improve sleep, manage anxiety, or simply become more mindful about how much caffeine you’re consuming.
We set out to create a simple ‘caffeine calculator’ to enable a quick approximate calculation of the caffeine in your cup.
There are three main factors that affect the caffeine in your cup of coffee:
- Caffeine content in the green coffee
- The dose of your brew
- The brew method
If you know these three things you can estimate how much caffeine in your cup.
The Equation
Caffeine (mg) = 1000 × D × G × R × B
- D = Dose of coffee used in the brew, in grams
- G = Green coffee caffeine percentage
- R = Roast adjustment factor = 1.15
- B = Brew method factor
Green Coffee Caffeine % (G)
To understand the caffeine content in our cups we start with the raw product: the green (un-roasted) coffee bean. Arabica coffee—the most common species used in specialty coffee—typically contains 1.4%–1.6% caffeine by weight in its green form. Naturally low-caffeine varieties, such as Laurina or Aramosa, fall within 0.4%–0.6% and 0.6%–1.0%, respectively. Decaf coffees sit below 0.1%, per EU and UK definitions.
This green bean caffeine percentage forms the base of your caffeine calculation.
We caffeine test our naturally lower caffeine coffees and report the result – so you could use this number in your calculation. For example our LO CAF BRAZIL Rio Brilhante has 1.00% caffeine in the green bean. If you don’t know the exact value you could use 1.50% for regular Arabica coffee, 0.10% for decaf coffee.
Roast Adjustment Factor (R)
Unlike certain flavour compounds, caffeine is heat stable at common roasting temperatures - meaning roasting does not destroy it. However, roasting does reduce the bean’s overall mass through water loss and chemical changes.
To account for this, we apply a Roast Adjustment Factor (R) of 1.15, which compensates for the concentration of caffeine due to roast-induced weight loss. This ensures your calculation reflects the final roasted bean’s caffeine contribution.
Effect of Dose
The amount of ground coffee you use—also known as the dose—plays a major role. A standard filter brew might use 15g, while espresso doses are often closer to 18g–20g.
Larger doses naturally deliver more caffeine. Our calculator multiplies the dose (in grams) by all other factors to estimate total caffeine in milligrams.
Effect of Brew Method
Different brew methods extract caffeine with different efficiencies.
For example, espresso uses pressure to extract a highly concentrated brew in a short time, while cold brew relies on long steeping. These brewing techniques influence how much of the caffeine in your ground coffee makes it into your cup.
We use a Brew Method Factor (B) to represent this:
|
Brew Method |
B Factor |
|
Cold Brew |
1.0 |
|
Pour Over |
0.9 |
|
Stovetop |
0.9 |
|
Aeropress |
0.8 |
|
Cafetiere |
0.8 |
|
Espresso |
0.7 |
These figures are based on measured extraction efficiencies and supported by research into brewing techniques and caffeine content. Surprisingly, a standard pour over filter is more effective at extracting caffeine than an espresso shot.
Example Calculation
Let’s say you brew a 15g cafetière using a low-caf from Brazil with 1.00% caffeine content. Here's how you’d calculate the caffeine:
Caffeine (mg) = 1000 × D × G × R × B
- D = 15g
- G = 0.01 (1%)
- R = 1.15
- B = 0.8 (cafetiere)
Result:
1000 × 15 × 0.01 × 1.15 × 0.8 = 138mg of caffeine
That’s a manageable, moderate amount—great if you’re aiming to reduce your overall daily intake.
Summary
Here’s the full formula again:
Caffeine (mg) = 1000 × Dose (g) × Green Caffeine % × Roast Factor × Brew Method Factor
This approach offers a practical way to estimate caffeine intake based on bean type, brew method, and dose. While real-world variation exists, this method provides a decent estimate for comparing different coffees and brewing styles.
At Calm Coffee Roastery, we have coffees at all caffeine levels along the spectrum – from Decaf to Full Caf. Take a look today to find a specialty coffee at the right caffeine level for you.
References
- European Food Safety Authority. (2015). Scientific Opinion on the safety of caffeine. EFSA Journal. https://doi.org/10.2903/j.efsa.2015.4102
- Angeloni, G., et al. (2019). What kind of coffee do you drink? An investigation on effects of eight different extraction methods. Food Research International, 1327–1335. https://doi.org/10.1016/j.foodres.2018.10.022
- Calm Coffee Roastery (2025). Caffeine Calculator: LCSP Leaflet – Front and Back. Internal publication.