RediCalc.com
Last updated: June 1, 2026

Caffeine Calculator

Track your caffeine intake from various beverages. See how close you are to the recommended daily limit and how long caffeine stays active.

Caffeine Details

Caffeine Results

Total Caffeine190mg
% of Daily Limit (400mg)48%
Room Left Today210mg
Active For (approx.)16.2 hours
Dose per kg2.8 mg/kg
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Understanding the Caffeine Calculator

A caffeine calculator estimates how much caffeine you are consuming from coffee, tea, energy drinks, and soda, and compares it against recommended daily limits. It helps you understand your intake and avoid the jitters, poor sleep, or dependence that excess caffeine can cause.

How much is too much

Health authorities generally consider up to about 400 mg of caffeine per day safe for most healthy adults — roughly four cups of brewed coffee. Sensitivity varies widely, though; some people feel fine at higher amounts while others get anxious or sleepless from a single cup. Pregnant people are usually advised to consume considerably less.

Timing affects sleep

Caffeine has a half-life of around five to six hours, meaning a sizable portion is still in your system long after you drink it. An afternoon coffee can quietly disrupt that night’s sleep. If you are sensitive or sleeping poorly, cutting off caffeine by early afternoon often makes a noticeable difference.

Tips & things to know

  • Up to ~400 mg/day is generally safe for healthy adults.
  • Caffeine lingers for hours — avoid it late in the day.
  • Sensitivity varies; pregnant people should limit intake more.

How Caffeine Works

Caffeine has a half-life of about 5 hours. The FDA recommends no more than 400mg per day for healthy adults.

Sources

  • FDA. "Spilling the Beans: How Much Caffeine is Too Much?"

How to Use the Caffeine Calculator

1

Open the Caffeine Calculator

Navigate to the Caffeine Calculator page on Redicalc. The calculator loads instantly with no sign-up required.

2

Enter your values

Fill in recipe quantities, ingredients, or cooking parameters. Toggle between metric and imperial units if available.

3

Review your results

Your caffeine results appear instantly as you type. Review the breakdown, charts, or detailed analysis provided.

4

Adjust and compare

Try different input values to compare scenarios. This helps you understand how changes affect the outcome.

5

Share or save your results

Use the copy or share buttons to save your results. You can also bookmark the page for quick access later.

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Frequently Asked Questions

How much caffeine is too much?

The FDA recommends a maximum of 400mg per day for most adults. That is roughly 4 cups of drip coffee.

How long does caffeine last?

Caffeine has a half-life of about 5 hours. So if you drink 200mg at noon, you still have ~100mg at 5 PM and ~50mg at 10 PM.