How much caffeine is too much for you? This free caffeine safe limit calculator estimates a general daily guideline from your body weight and shows how much room you have left based on what you’ve already had.
A cup of coffee has roughly 95mg, black tea ~47mg, and a typical energy drink 80-150mg.
This uses a general 400mg adult guideline (capped by a weight-based estimate). Pregnant individuals, teens, and those with certain health conditions should use a much lower limit – check with a doctor.
How the Caffeine Safe Limit Calculator Works
This tool estimates a general daily caffeine guideline based on your body weight, then compares it against how much caffeine you have already had today to show how much room you have left. It uses a commonly cited weight-based allowance capped at the general 400mg adult guideline.
Formula: Weight (kg) = Body weight (lb) × 0.453592. Daily limit = the smaller of 400mg or (Weight in kg × 6mg). Remaining today = Daily limit − Caffeine consumed today. % of limit used = (Caffeine consumed today ÷ Daily limit) × 100.
- Body weight (lb) — your body weight in pounds, used to estimate a weight-scaled caffeine allowance
- Caffeine consumed today (mg) — the total caffeine you have already had today, from coffee, tea, energy drinks, or other sources
Example Scenarios
| Body Weight (lb) | Consumed Today (mg) | Remaining Today (mg) |
|---|---|---|
| 90 | 50 | 195 mg (limit 245 mg) |
| 100 | 100 | 172 mg (limit 272 mg) |
| 130 | 200 | 154 mg (limit 354 mg) |
| 150 | 150 | 250 mg (limit 400 mg, capped) |
| 160 | 300 | 100 mg (limit 400 mg, capped) |
| 200 | 450 | -50 mg (limit 400 mg, capped) |
Caffeine Safe Limit Calculator FAQ
Where does the 400mg daily caffeine guideline come from?
400mg per day is a general guideline commonly cited by health authorities for healthy adults, roughly equivalent to about four cups of coffee. This calculator uses it as an upper cap on top of a weight-scaled estimate, not as a target to reach.Why is my daily limit lower than 400mg?
The calculator estimates an allowance of about 6mg of caffeine per kilogram of body weight, then caps that number at 400mg. If your weight-based estimate comes out below 400mg, the lower number is shown as your limit.How much caffeine is in a typical cup of coffee or energy drink?
A typical cup of coffee has roughly 95mg of caffeine, black tea has roughly 47mg, and energy drinks commonly range from about 80 to 150mg per can, though exact amounts vary widely by brand and serving size.Should pregnant women use the same limit shown by this calculator?
No. This calculator applies a general adult guideline, but pregnant individuals, teens, and people with certain health conditions or medications are typically advised to use a much lower limit. Check with a doctor for guidance specific to your situation.What does it mean if my “remaining today” shows a negative number?
A negative remaining amount means your reported consumption already exceeds the estimated daily limit for your weight. It is a signal to be mindful of further caffeine intake for the rest of the day, not a medical alert.Does this calculator account for caffeine sensitivity or tolerance?
No. It only scales a general guideline by body weight; it does not adjust for individual factors like caffeine tolerance, sleep sensitivity, medications, or health conditions that can meaningfully change a safe amount for any one person.Related Calculators
Caffeine intake also connects to how you sleep and hydrate, so you might also try the caffeine half-life calculator to see how long caffeine lingers in your system, the sleep calculator to plan around a late cup of coffee, or the water intake calculator for general daily hydration guidance.