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Estimate your daily caffeine intake in mg, compare it with age‑appropriate safe limits, and see whether you may be overdoing coffee, energy drinks, or soda.
Caffeine is the world's most widely consumed psychoactive substance, found in coffee, tea, energy drinks, soft drinks, chocolate, and many medications. For most healthy adults, up to about 400 mg of caffeine per day is generally considered safe—roughly the amount in four 8-ounce cups of brewed coffee.
However, your personal safe range depends on multiple factors: age, body weight, pregnancy status, medications, health conditions, and individual sensitivity. Some people feel jittery, anxious, or experience heart palpitations at much lower doses, while others tolerate higher amounts without issue.
This calculator adds up caffeine from all your daily sources and compares the total to age- and situation-appropriate guidelines. It also calculates your caffeine per kg of body weight, since higher mg/kg doses are more likely to trigger side effects.
Different populations have different recommended limits based on research into health effects:
The FDA, European Food Safety Authority, and most health organizations cite 400 mg/day as a safe upper limit for most healthy adults. This amount is not associated with negative health effects in clinical studies. However, individual responses vary significantly.
Most guidelines recommend 200 mg/day or less during pregnancy and breastfeeding. Higher caffeine intake has been associated with increased risk of miscarriage and low birth weight in some studies, though evidence is mixed. Many healthcare providers recommend staying well under 200 mg to be cautious.
The American Academy of Pediatrics suggests teens should limit caffeine to 100 mg/day or less—roughly one cup of coffee. Developing brains and bodies are more sensitive to caffeine's effects on sleep, anxiety, and heart rate.
Most pediatric guidelines recommend children consume minimal caffeine, with rough limits around 2.5 mg per kg of body weight per day at most. Many experts recommend avoiding caffeine entirely for young children.
Watch for these symptoms that may indicate overconsumption:
Caffeine has a half-life of about 5-6 hours in most adults, meaning half the caffeine from your morning coffee is still in your system 5-6 hours later. This is why afternoon caffeine can significantly impact sleep even if you feel fine when going to bed.
Some factors that slow caffeine metabolism (extending half-life):
If you're sensitive to caffeine's sleep effects, consider cutting off caffeine intake at least 8-10 hours before bedtime.
Talk with a healthcare professional about your personal caffeine limits if you:
If you're consuming too much caffeine and want to cut back, gradual reduction is key to avoiding withdrawal symptoms:
If you regularly consume caffeine and suddenly stop, you may experience withdrawal symptoms including:
Symptoms typically begin 12-24 hours after last caffeine intake, peak at 20-51 hours, and resolve within 2-9 days. Gradual reduction minimizes these effects.
No. This tool provides educational estimates based on public health guidance (like 400 mg/day for most adults and 200 mg/day or less in pregnancy). It cannot diagnose caffeine sensitivity, caffeine use disorder, or other health problems. Always follow your doctor's advice if you have medical conditions affected by caffeine.
Caffeine sensitivity varies significantly due to genetics and other factors. Some people feel anxious, jittery, or have heart palpitations even at modest doses (50-100 mg). If you regularly notice unpleasant symptoms after caffeine, your personal limit may be much lower than general guidelines. Consider tracking your response and consulting a healthcare professional.
No. Actual caffeine content varies widely by bean type, roast level, brew method, and serving size. A Starbucks "Grande" coffee contains around 310 mg—nearly your full daily limit—while a home-brewed 8 oz cup might have 95 mg. Espresso-based drinks vary by the number of shots. This calculator uses typical averages; check specific products when possible.
Caffeine has a half-life of about 5-6 hours in most adults, meaning half the caffeine is still in your system after that time. A 200 mg coffee at noon means ~100 mg at 5-6 PM, ~50 mg at 10-11 PM, etc. This is why afternoon caffeine can disrupt sleep even if you feel fine at bedtime.
Yes. Regular caffeine consumption leads to tolerance, meaning you need more to feel the same effects. Your body also becomes dependent, leading to withdrawal symptoms when you stop. This tolerance can develop within 1-4 days of regular use and is why some people feel they "need" coffee to function normally.
For most healthy adults, moderate caffeine consumption (up to 400 mg/day) is not associated with increased heart disease risk. However, very high doses can cause temporary increases in blood pressure and heart rate. People with existing heart conditions, arrhythmias, or high blood pressure should consult their doctor about appropriate limits.
Contrary to popular belief, darker roasts actually have slightly less caffeine than lighter roasts (the roasting process burns off some caffeine). However, the difference is small. Brew method and serving size have much larger impacts on total caffeine content.
Caffeine can temporarily boost metabolism and fat oxidation, which is why it's included in many weight loss supplements. However, the effect is modest (3-11% metabolic increase) and tolerance develops. Caffeine is not a substitute for healthy eating and exercise, and high doses carry risks.