Caffeine Clearance Calculator
Estimate how long caffeine stays in your system with a caffeine half-life calculator, intake tracker, clearance time, and sleep impact chart.
The Drink
8 fl oz cup preset
Auto-calculated from preset — edit if your drink differs
Today's log
No drinks logged yet. Add coffee, tea, or an energy drink to start.
About You
- Add at least one caffeine intake to run the analysis.
Use this free caffeine calculator to estimate how long caffeine stays in your system, when caffeine may wear off, and how much active caffeine could remain at bedtime. Log coffee, espresso, tea, energy drinks, pre-workout, caffeine pills, or a custom milligram dose, then personalize the caffeine half-life estimate with age, body weight, smoking status, oral contraceptive use, pregnancy trimester, CYP1A2 metabolism, liver health, and target bedtime. The calculator uses a first-order exponential decay model to show current active caffeine, estimated clearance time below 10 mg, sleep impact risk, and a caffeine metabolism curve. Everything runs locally in your browser, so your caffeine intake log and health details stay on your device.
How to Use Caffeine Clearance Calculator
Use the caffeine intake calculator
Start by adding each caffeine source you consumed today. Choose a preset for drip coffee, espresso, cold brew, black tea, green tea, cola, energy drinks, pre-workout, or caffeine pills, or enter a custom caffeine amount from a product label. Set the exact time consumed so the calculator can estimate how much caffeine remains now and later.
Log multiple coffees, teas, or energy drinks
Caffeine does not reset after each drink. If you drink coffee in the morning and an energy drink in the afternoon, the remaining caffeine from the first drink stacks with the later dose. Add every intake event to build one combined caffeine clearance curve for the day.
Personalize your caffeine half-life
The average caffeine half-life is often described as about 5 hours, but real metabolism varies. Use the About You section to adjust for age, body weight, gender, smoking, oral contraceptive use, pregnancy trimester, optional CYP1A2 fast or slow metabolizer status, liver health, and target bedtime.
Check how much caffeine is still active
The current caffeine level estimates how many milligrams may still be active in your body right now. This helps answer searches like "how much caffeine is still in my system?", "when will my coffee wear off?", and "how long does an energy drink last?"
Find your caffeine clearance time
The clearance result estimates when your active caffeine level drops below 10 mg. Because caffeine decays by half-lives, a 200 mg dose can take many hours to become very low, especially for slow metabolizers, pregnant users, oral contraceptive users, or anyone logging multiple drinks.
Plan caffeine before bed
Enter your target bedtime to see a sleep impact warning. The calculator projects caffeine remaining at bedtime and labels the risk as low, moderate, or high, making it useful as a coffee before bed calculator or caffeine sleep calculator.
Read the caffeine metabolism chart
The chart plots active caffeine over time and includes threshold lines for jitter, focus range, and sleep disruption risk. Change any drink, time, or personal factor and the metabolic curve updates instantly without a page reload.
Calculator Features
Coffee, tea, energy drink, and pill presets
Estimate caffeine from drip coffee, espresso, cold brew, black tea, green tea, cola, energy drinks, pre-workout, caffeine pills, or a custom mg amount.
Caffeine intake calculator with multiple doses
Log several drinks in one day and combine overlapping caffeine decay curves instead of treating each cup or supplement as a separate event.
Personalized caffeine half-life calculator
Starts from a 5-hour baseline and adjusts for smoking, oral contraceptives, pregnancy, CYP1A2 status, liver health, age, and gender.
Caffeine clearance and wear-off time
Estimate current active caffeine, time until caffeine drops below 10 mg, and the projected curve for the next several hours.
Caffeine sleep impact calculator
Project how much caffeine may remain at your target bedtime and identify low, moderate, or high sleep disruption risk.
Metabolic curve chart with thresholds
Visualize caffeine remaining over time with lines for jitter, focus range, sleep disruption, and practical clearance.
Private local caffeine tracker
Your profile and caffeine log are stored in browser local storage. No account, no automatic upload, and no server-side health profile.
Complete Function List
- Caffeine intake calculator for coffee, tea, energy drinks, pre-workout, pills, and custom mg doses
- Answers "how long does caffeine stay in your system?" with a personalized estimate
- Caffeine half-life calculator with an adjustable personal metabolism model
- Multiple caffeine intake events in one day
- Preset beverages with serving-based milligram estimates
- Custom caffeine milligram input from nutrition labels
- Exact time-of-consumption logging
- Current active caffeine level in mg
- Estimated time until caffeine drops below 10 mg
- Caffeine wear-off estimate for coffee, tea, energy drinks, and supplements
- Bedtime caffeine projection and sleep risk warning
- Metabolic curve chart with jitter, focus, and sleep threshold lines
- Lifestyle and physiology factors: age, weight, gender, smoking, pregnancy, oral contraceptives, CYP1A2, and liver health
- Real-time recalculation on every input change
- Local browser storage for profile and intake history
- Mobile-first responsive interface for logging drinks on the go
- No sign-up required
- Educational guidance with medical caution for pregnancy, liver disease, and medication interactions
Common Calculations & Examples
Example 1: How long will coffee stay in my system?
Problem: You drank a cup of coffee at 2:00 PM and want to know whether caffeine may still be active tonight.
Steps:
- Select Drip Coffee and set the serving count.
- Enter 2:00 PM as the time consumed.
- Add your age, bedtime, and any relevant metabolism factors.
- Review current caffeine, clearance time, and the bedtime sleep warning.
Explanation: Coffee may feel like it wears off after a few hours, but measurable caffeine can remain much longer. The calculator separates perceived alertness from the underlying half-life curve.
Example 2: Calculate caffeine before bed
Problem: You are considering an afternoon latte, tea, or energy drink and want to avoid a bad night of sleep.
Steps:
- Add the drink and time you plan to consume it.
- Set your target bedtime.
- Compare projected caffeine at bedtime before deciding whether to drink it.
Explanation: Caffeine can reduce sleep quality even when you feel tired enough to fall asleep. Looking at residual caffeine at bedtime is more useful than guessing from the initial buzz.
Example 3: Track multiple coffees and an energy drink
Problem: You had coffee in the morning, another cup after lunch, and an energy drink later in the day.
Steps:
- Log each coffee and energy drink with its own time.
- Use custom mg values if you know the label amount.
- Check the active caffeine total and metabolic curve.
Explanation: Caffeine doses overlap. Remaining caffeine from earlier drinks continues decaying while later drinks add new caffeine on top, which can push bedtime levels higher than expected.
Example 4: Compare fast vs slow caffeine metabolism
Problem: You know your CYP1A2 result or suspect you are sensitive to caffeine and want a more personal estimate.
Steps:
- Set CYP1A2 status to Fast metabolizer or Slow metabolizer.
- Add the same drink and time you normally use.
- Compare half-life, clearance time, and bedtime projection.
Explanation: CYP1A2 is a major enzyme involved in caffeine metabolism. Genetics do not explain everything, but they are one useful signal when estimating caffeine half-life.
Example 5: Estimate pre-workout caffeine clearance
Problem: You took a high-caffeine pre-workout before training and want to know when it may stop affecting sleep.
Steps:
- Choose Pre-Workout or enter the exact caffeine mg from the label.
- Set the time you took it.
- Review the jitter threshold, sleep threshold, and estimated clearance time.
Explanation: Pre-workout products often contain more caffeine than one cup of coffee. A larger dose takes more half-lives to fall below low residual levels.