Caffeine Intake Calculator
Enter drink servings, volume, and caffeine per serving to estimate daily caffeine, source shares, and an adult reference comparison.
Estimated result
About 64% of the 400 mg/day reference. This is not a personal safety allowance.
A share link writes drink names, volume, caffeine per serving, servings, and context into the URL. Send it only if you are comfortable sharing those inputs.
How to understand the result
The total is an estimate
Each source is servings multiplied by caffeine per serving. Better label, brand, or measured data produces a more useful estimate.
The adult reference is not a diagnosis
FDA says 400 mg/day is an amount not generally associated with dangerous negative effects for most adults. Sensitivity, timing, health, and medicines still matter.
Start with the largest source
Source shares show the main contributor. Verify its serving size, number of servings, and label value before changing smaller sources.
How to use the caffeine calculator
- Add each caffeine source
Choose a preset or enter a drink or brand, serving volume, caffeine per serving, and number of servings.
- Check the editable values
Confirm the label milligrams and serving size; switch volume units if needed.
- Review the total and limits
Calculate the total, inspect source shares, then read the reference context, uncertainty, and action guidance.
Formula, example, and limits
Formula, units, and rounding
- Servings may range from 0 to 50; caffeine per serving may range from 0 to 1,000 mg.
- Volume documents serving size but does not alter the entered mg value. 1 US fl oz = 29.5735295625 ml.
- The calculation retains full precision; totals and percentages are formatted only for display.
- The 400 mg comparison is an FDA reference for generally healthy adults, not a personal tolerance calculation.
Example: two coffees and one energy drink
2 × 95 mg brewed coffee + 1 × 64 mg energy drink = 254 mg. Coffee contributes about 75% and the energy drink about 25%.
Scope and action guidance
- Pregnancy, breastfeeding, children, adolescents, cardiovascular conditions, and medicine interactions require more cautious individual guidance than the general adult comparison.
- Coffee beans, tea, brewing, cup size, extra espresso shots, and product formulation can substantially change actual caffeine.
- The total includes only entered sources and does not automatically add chocolate, supplements, medicines, or unrecorded drinks.
- The result is a general health-management estimate, not diagnosis, treatment, or individualized nutrition advice.
Privacy and local processing
All calculations run in this browser. There is no upload, third-party runtime request, cookie, or localStorage write. Clipboard access occurs only after you choose a copy action.
Data and method sources
US FDA: Spilling the Beans—How Much Caffeine is Too Much? supports the adult reference, individual variability, and common drink ranges.
USDA FoodData Central can be used to look up food and drink data; actual labels and brand data should take priority for a specific product.
Independent native JavaScript with no third-party calculation library; presets are editable examples, not universal brand values.
Content and source review: 31 July 2026.
Frequently asked questions
How much caffeine per day is appropriate?
There is no single number for everyone. FDA says 400 mg/day is not generally associated with dangerous negative effects for most adults, but sensitivity, health, medicines, and timing change the response. Special groups need individual guidance.
Why does caffeine vary between cups of the same drink?
Bean or leaf type, grind, dose, water, brewing time, extraction, cup size, and extra shots all matter. That is why the page lets you edit the brand, volume, and caffeine per serving.
How many cups of coffee is too much?
Cup count cannot answer reliably because serving size and caffeine per cup vary widely. Check a label or brand value, total all daily sources, and do not keep adding caffeine when symptoms occur.
Can energy drinks and coffee be compared by cup count?
Not reliably. Volume, formulation, and caffeine per serving differ, and one container may include multiple servings. Enter label milligrams, servings per container, and the amount actually consumed.