Caffeine Intake Calculator
Track your daily caffeine intake from coffee, tea, soda, and energy drinks. Compare against FDA recommendations.
About this calculator
This calculator adds up caffeine from four everyday sources using published average concentrations — about 12mg per ounce of brewed coffee, 47mg per 8oz cup of tea, 34mg per 12oz can of soda, and 160mg per energy drink can — then compares your daily total against the FDA's own published guidance, which names 400mg a day — roughly two to three 12-ounce cups of coffee — as the amount "not generally associated with negative effects" for most healthy adults. Coffee is scaled by both cup count and the serving size you select, since a 20oz large coffee delivers proportionally more caffeine than an 8oz small at the same per-ounce concentration, while tea, soda, and energy drinks are treated as fixed per-serving amounts regardless of size. The "hours to clear system" figure models caffeine's roughly 5.5-hour average half-life, estimating how long it takes your total dose to decay down to a residual baseline of about 10mg — a genuine exponential decay calculation, though real clearance time varies substantially between individuals based on genetics, liver enzyme activity, pregnancy, and medications, so treat the hours figure as a rough midpoint rather than a personalized estimate.
The body weight field is included for reference only and does not currently factor into any calculation here, since these are population-average concentrations rather than a weight-adjusted dosing model; a more precise mg-per-kilogram assessment would need to scale the FDA threshold to your actual body mass rather than using the flat 400mg figure. Every source total is also a population average — actual caffeine content varies by brewing method, bean or leaf type, and brand, sometimes substantially for coffee in particular.
Inputs
Results
Daily Caffeine
335 mg
Figures current as of 2024. Source: U.S. Food and Drug Administration, "Spilling the Beans: How Much Caffeine is Too Much?" (content current as of Aug. 28, 2024)
How to Use This Calculator
- Enter the number of coffees, teas, sodas, and energy drinks you consume per day.
- Select the coffee cup size that matches your typical serving.
- Optionally enter your body weight (advanced field) for reference — it does not currently change the calculated results.
- The calculator shows total daily caffeine in mg, percentage of the 400 mg FDA limit, and hours until it clears your system.
- Adjust beverage counts to find a daily intake within a healthy range.
How the result changes with Coffees per Day
| Coffees per Day | Daily Caffeine |
|---|---|
| 1 | 191 mg |
| 1.5 | 263 mg |
| 3 | 479 mg |
| 5 | 767 mg |
What each input means
- Coffees per Day
- Number of cups of coffee you drink each day
- Coffee Size
- Typical size of each coffee serving in fluid ounces
- Teas per Day
- Number of 8 oz cups of tea consumed daily — about 47mg caffeine each
- Sodas per Day
- Number of 12 oz cans of caffeinated soda consumed daily
- Energy Drinks per Day
- Number of energy drink cans consumed daily — about 160mg caffeine each
- Body Weight
- Your body weight — affects how caffeine is metabolized
How this is calculated
Formula
Coffee: ~12mg/oz, Tea: ~47mg/cup, Soda: ~34mg/can, Energy drinks: ~160mg/can. FDA recommends ≤400mg/day for adults.Worked example, using the default values
- Identify Input Parameters4 parametersCoffees per Day = 2, Coffee Size = 12, Teas per Day = 1, Sodas per Day = 0 = 6 input(s) provided
- Calculate Daily CaffeineDaily Caffeine335 = 335
- Calculate % of FDA Limit% of FDA Limit84 = 84%
- Calculate AssessmentModerate — within FDA recommendation = Moderate — within FDA recommendation
Figures and sources
- FDA guidance on daily caffeine intake for healthy adults (400 mg/day) (2024) — U.S. Food and Drug Administration, "Spilling the Beans: How Much Caffeine is Too Much?" (content current as of Aug. 28, 2024)
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't entering my body weight change any of the results?
The calculation compares your caffeine intake against the FDA's flat 400mg-per-day guidance, which is a population-wide recommendation rather than a weight-scaled dose, so this calculator doesn't currently adjust the limit or your totals based on body weight. A smaller person and a larger person consuming the same drinks get identical output here, even though caffeine's physiological effect per kilogram of body mass does differ between them.
How accurate is the 'hours to clear system' estimate?
It's a genuine exponential-decay calculation based on caffeine's average 5.5-hour half-life, estimating how long your total dose takes to fall to a small residual amount. But that half-life varies widely between individuals — smokers metabolize caffeine roughly twice as fast as non-smokers, pregnancy can double or triple it, and certain medications and liver conditions slow it further — so the number is a population-average midpoint, not a personal prediction.
Why does a large coffee count for more caffeine than a small one at the same number of cups?
Coffee's caffeine content scales with volume — roughly 12mg for every fluid ounce — so a 20oz extra-large cup contains about two and a half times the caffeine of an 8oz small cup even though both count as "one coffee." Tea, soda, and energy drinks are treated as fixed amounts per typical serving instead, since this calculator doesn't ask for their size separately.
Is 400mg a safe limit for everyone, or does it vary by person?
The FDA's 400mg figure is a general guideline for healthy, non-pregnant adults without a caffeine sensitivity, and it is not appropriate for everyone — pregnant individuals are typically advised to stay well under 200mg, and people with certain heart conditions, anxiety disorders, or caffeine sensitivities may experience adverse effects at doses well below 400mg. This calculator's assessment tiers use that adult guideline as a reference point, not a universal safety threshold.
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