What Is Your Safe Daily Caffeine Limit?
How caffeine affects your body depends heavily on your weight and individual sensitivity. As a general guideline, a safe daily caffeine limit for healthy adults is roughly 3-6mg per kg of body weight, capped at 400mg regardless of weight. This calculator uses your body weight and self-reported caffeine sensitivity (low, normal, or high) to calculate a personalized daily limit in mg, then converts it into cups of coffee (based on about 95mg per 8oz cup) so you know roughly how many cups is safe.
Why the Safe Amount Differs Even at the Same Weight
The liver enzyme that breaks down caffeine (CYP1A2) varies a lot in activity from person to person, which is why the same cup of coffee leaves one person unaffected while another feels jittery or cannot fall asleep. If you tend to be more sensitive, it is safer to set your limit lower relative to your body weight, and avoiding caffeine after roughly 2pm helps protect sleep quality. Remember that caffeine is not just in coffee — green tea, energy drinks, and chocolate all contribute, so your true daily total should account for all of them combined.
Do not Ignore Signs of Overconsumption
Taking in more caffeine than your safe limit can cause hand tremors, a racing heart, anxiety, headaches, and trouble sleeping. If these symptoms show up repeatedly, cutting back your daily intake or switching to decaf can help. Pregnant individuals and people with heart conditions are generally advised to keep intake lower than the standard guideline, so it is worth checking with a doctor if either applies to you.
Frequently Asked Questions
If just one cup of coffee makes your heart race or keeps you up at night, you likely have high sensitivity. If you can drink coffee in the evening and still sleep fine, your sensitivity is likely low. Choose Normal if you are unsure.
No. Green and black tea, energy drinks, chocolate, and some pain relievers also contain caffeine, so combining several sources can push your daily total up faster than you expect.