Coffee Kick Calculator
See how much caffeine you’re consuming and how it affects your body over time.
Total number of servings consumed today.
Typical 8 oz cup of brewed coffee.
Multiply your weight in pounds by 0.4536 to convert to kilograms.
Used to estimate remaining caffeine in your system.
Total Caffeine Consumed
285 mg
71% of 400 mg daily guideline
Residual Caffeine
216 mg in system
3.1 mg/kg body weight (Moderate impact)
How to Use This Calculator
Record today’s caffeine beverages
Enter how many servings you drank and pick the closest drink type.
Add your body weight
Body weight helps estimate safe intake per kilogram.
Check the caffeine remaining
Residual caffeine declines with a 5-hour half-life. See how alert you might still feel.
Formula
totalCaffeine = servings × caffeinePerServing
residual = totalCaffeine × (0.5)(hours/5)
mgPerKg = residual ÷ bodyWeightKg
Example: 2 drip coffees (95 mg each) → 190 mg. After 4 hours → 190 × 0.5^(4/5) ≈ 120 mg remaining.
Guidelines: Most adults should limit caffeine to 400 mg/day; pregnant individuals to 200 mg/day.
Full Description
Caffeine stimulates the central nervous system, enhancing alertness and energy. This calculator helps you monitor intake so you stay within recommended safety limits. It considers both the immediate caffeine consumed and how much remains in your system based on caffeine’s half-life.
Drink choices have different caffeine contents depending on bean variety, roast, brewing time, and serving size. We use widely accepted averages. Energy drinks and cold brew can be especially potent; adjust servings accordingly.
When to use
- Planning study or work sessions requiring alertness.
- Tracking caffeine in athletes’ nutrition plans.
- Monitoring intake during pregnancy or when managing anxiety.
- Teaching students about stimulant pharmacokinetics.
Sensitivity varies by genetics, age, and tolerance. If you experience jitters or sleep disruption, reduce servings or choose decaffeinated options. Stay hydrated, and avoid stacking caffeine with other stimulants.
Frequently Asked Questions
How accurate are caffeine values?
They are averages. Actual caffeine can vary ±20%. Check manufacturer labels when available.
What is a safe caffeine dose?
Up to 400 mg per day for healthy adults, according to the FDA. Individuals with health conditions should consult doctors.
How long does caffeine stay in my system?
Half of it is metabolized in about 5 hours, but this varies with liver function, smoking status, and medications.
Does decaf have caffeine?
Yes, but much less—typically 2 to 5 mg per 8 oz cup. Consider it if you’re near your limit.