βοΈ Caffeine Intake Calculator
Add up your drinks, check the 400 mg line, and time your last cup.
Estimates from typical values; actual caffeine varies by brand and brew.
Most caffeine drinkers have no idea how much they actually consume. A "coffee" can be 95 mg or 300 mg depending on size and brew, and energy drinks hide enormous doses behind small cans. Click your drinks above to total your intake in milligrams, see where you stand against the FDA's 400 mg daily guideline, and estimate how much is still in your system right now.
How to Use This Calculator
Tap each drink you have had today. The total, guideline percentage, and remaining caffeine update live.
Click a button for every serving: coffee, tea, soda, energy drink, chocolate. Sizes are standardized to typical servings.
Add anything unusual with the custom field: pre-workouts, caffeine pills, matcha lattes.
Enter how many hours ago your last caffeine was, to estimate what is still circulating (half-life about 5.5 hours).
Compare against 400 mg. If sleep is the issue, also check our sleep cycle calculator and circadian rhythm guide.
Caffeine Content of Common Drinks
These are USDA and manufacturer typical values; real numbers swing with brew strength, bean, and brand. Cold brew surprises people because long steeping extracts more caffeine, and "one coffee" at a shop is often 16 to 20 ounces, doubling the 8-ounce figures. Pre-workouts are the wild west at 200 to 400 mg per scoop, sometimes more, which is why the custom field exists. Chocolate and some medications contribute small amounts most people forget.
The FDA's 400 mg guideline applies to healthy adults: roughly four small brewed coffees. It is not a target, it is a ceiling, and sensitivity varies enormously with genetics, tolerance, anxiety, and pregnancy. Pregnant women are generally advised to stay under 200 mg. If 200 mg makes you jittery, your personal limit is 200 mg regardless of what the guideline says.
Worked Example
Two 8-ounce brewed coffees (190 mg), one 12-ounce cola at lunch (34 mg): total 224 mg, or 56 percent of the 400 mg guideline, comfortably inside it. Add a 2-ounce energy shot at 3 pm (200 mg): total 424 mg, over the line. With a 5.5-hour half-life, that 3 pm shot still leaves about 100 mg circulating at 10 pm, roughly a full small coffee's worth at bedtime. That single afternoon decision explains more bad sleep than most people realize.
Half-Life: Why Timing Beats Total
Caffeine's half-life averages about 5.5 hours but ranges from 3 to 7 between people, longer with certain medications and oral contraceptives, shorter in smokers. After one half-life, half remains; after two, a quarter. A 200 mg coffee at 4 pm leaves 100 mg at 9:30 pm and 50 mg at 3 am. Studies show caffeine even 6 hours before bed measurably shortens sleep, which is why the practical cutoff is early afternoon for sensitive sleepers and noon-ish for the very sensitive. The calculator's "still in your system" row makes this concrete for your actual intake.
My rule: no caffeine within 8 hours of bed if you value sleep, 10 if you are sensitive. Morning people who "need" an afternoon coffee usually need a walk and water instead; the 3 pm slump is circadian, not a caffeine deficiency. And if you are using caffeine to survive on 5 hours of sleep, the honest fix is the sleep, not the dose.
Dependence, Tolerance, and Quitting
Daily use builds tolerance in about a week and dependence soon after: skip a day and the headache, fatigue, and irritability are withdrawal, not personality. None of this is dangerous at moderate doses, but it means your "need" for morning coffee is largely your brain collecting yesterday's debt. To cut back, taper by about 25 percent every few days rather than quitting cold; mix decaf into your brew, shrink serving sizes, and move the last cup earlier. Withdrawal peaks at 1 to 2 days and fades within a week. Most people who taper are surprised how little they miss the afternoon cup once sleep improves.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
How much caffeine is safe per day?
The FDA cites 400 mg daily as an amount not generally associated with dangerous effects in healthy adults, roughly four small brewed coffees. It is a ceiling, not a target. Pregnant women are generally advised to stay under 200 mg, and sensitive individuals should go lower.
How much caffeine is in a cup of coffee?
About 95 mg per 8 ounces of brewed coffee, 64 mg per espresso shot, and around 200 mg in 12 ounces of cold brew. Shop servings are often 12-20 ounces, multiplying those numbers. Actual content varies by bean, brew method, and brand.
How long does caffeine stay in your system?
Half-life averages about 5.5 hours (range 3-7). A 200 mg coffee at 4 pm leaves roughly 100 mg at 9:30 pm and 50 mg at 3 am. Caffeine taken even 6 hours before bed measurably shortens sleep in studies.
When should I stop drinking caffeine before bed?
At least 8 hours before bedtime, 10 if you are sensitive. For an 11 pm bedtime, that means no caffeine after 1-3 pm. The afternoon slump most people treat with coffee is circadian and passes on its own.
Is 400 mg of caffeine a lot?
It is the top of the moderate range: about four small coffees or two strong energy drinks. Many daily drinkers exceed it without realizing, especially with energy drinks and pre-workouts. Track a typical day above to see where you land.
Can caffeine cause anxiety?
Yes, especially above personal tolerance. Caffeine blocks adenosine and raises adrenaline, which mimics anxiety symptoms: jitteriness, racing heart, racing thoughts. Anxiety-prone people often do better under 100-200 mg or switching to tea, which adds calming L-theanine.
How do I quit caffeine without headaches?
Taper, don't jump. Cut about 25 percent every few days: mix decaf into regular, shrink servings, drop the afternoon cup first. Withdrawal headaches peak at 1-2 days and fade within a week. Hydration and regular sleep blunt the symptoms.
Does caffeine dehydrate you?
Mildly at most. Caffeine is a weak diuretic, but regular coffee drinkers develop tolerance to that effect, and the water in the drink more than compensates. Coffee counts toward daily fluid intake for habitual drinkers.
How much caffeine is in pre-workout?
Typically 150-400 mg per scoop, with some products exceeding that. Because serving sizes and "proprietary blends" obscure the dose, check the label and use the custom field above. Never double-scoop to compensate for tolerance.
Is caffeine bad for your heart?
Moderate intake (up to 400 mg) is not linked to heart disease in healthy adults and may even associate with lower risk in some studies. But high doses can trigger palpitations and raise blood pressure temporarily, and people with arrhythmias should discuss intake with their cardiologist.