CaffeineSleepCalc — pharmacokinetic caffeine metabolism and sleep calculator
⚗ Pharmacokinetics-based · Science-backed

Free Caffeine Cutoff Calculator
for Better Sleep

Enter the caffeinated drinks you had today and your planned bedtime to estimate your personalized caffeine cutoff time. Adjust your caffeine metabolism profile and body weight to see how they may affect the estimate.

N N N N C C C C C O O CH₃ CH₃ CH₃ C₈H₁₀N₄O₂ caffeine 194.19 g/mol
How it works
☕
① Log your drinks
Enter every caffeinated drink you had today and the time you had it — coffee, tea, soda, or energy drink.
⚗️
② We model your caffeine
Our pharmacokinetics model estimates how much caffeine will remain in your body at bedtime, personalized by your metabolism and body weight.
🌙
③ Get your sleep plan
See your estimated caffeine cutoff time, bedtime caffeine level, optimal wake-up times, and personalized sleep tips — all in one place.
💡 Example: You had a drip coffee at 8 AM and an espresso at 1 PM. Your bedtime is 10:30 PM. The calculator estimates 46mg of caffeine still active at bedtime — below the selected 50mg modeling target, but above the sensitive 20mg threshold. Enter your own drinks below to see your personalized result.
Your profile
Today's caffeine intake
Drink type
Time
Results
Total caffeine — mg consumed today
At bedtime — mg still in system
Last safe drink at —
☕ Estimated caffeine at bedtime
The needle shows how much caffeine will remain in your system at bedtime. The marker indicates your selected target level of 50 mg. Individual responses vary — this is a modeling estimate, not a medical safety limit.
0 mg 100 mg 200 mg 300 mg 400+ mg
Caffeine half-life for your metabolism
5h
Every 5h, ~50% of caffeine is cleared by hepatic CYP1A2 enzymes.
Estimated caffeine remaining (mg) Your drinks, metabolism, target and bedtime on one timeline
Caffeine Target Bedtime

Estimated caffeine remaining over time Line chart showing estimated caffeine decay with bedtime marker and target line

Estimate based on an assumed caffeine half-life. Individual caffeine metabolism varies considerably.

Share your result
CaffeineSleepCalc.com — My Caffeine Plan
🛑 Caffeine cutoff
—
🌙 Bedtime
—
📊 At bedtime
—
🎯 Target
—
⚗️ Metabolism profile
—
Status
—
caffeinesleepcalc.com
🌙 Dark ☀️ Light

💡 Print / Save as PDF opens your plan in a new tab — then choose Save as PDF from the print dialog.

Personalized sleep tips
Optimal wake-up times
🌙 Sleep Cycle Calculator
Based on your bedtime, sleep cycles vary in duration throughout the night, so these are approximate wake-up windows rather than precise predictions. A 15-minute sleep latency is included as an estimate. Bold = recommended 5-cycle window.
Hit Calculate above to see your optimal wake-up times.
Pharmacokinetic model
⚗️
First-order, one-compartment elimination model
Standard clinical pharmacokinetics for oral caffeine absorption
// Plasma concentration at time t after a single dose:
C(t) = C₀ × e^(−k·t)    where k = ln(2) / t½

// Multiple doses (superposition):
C_total(t) = Σ Dᵢ × e^(−k·(t − tᵢ))

// CYP1A2 phenotype half-lives:
Fast ≈ 3h · Normal ≈ 5h · Slow ≈ 8h
C(t)
Plasma level at time t
mg in system
C₀ / Dᵢ
Initial / per-dose amount
mg per drink
t½
Elimination half-life
3h · 5h · 8h
k
Elimination rate
ln(2) / t½
CYP1A2
Metabolic enzyme
Hepatic P450
Vd
Distribution volume
0.6 L/kg × weight
Caffeine metabolism factors & safety

🧬 Factors affecting metabolism

  • CYP1A2 genetics — polymorphisms can halve or double clearance rates
  • Age — neonates clear caffeine very slowly (t½ up to 100h); declines in healthy adults
  • Pregnancy — t½ rises to ~15h in the 3rd trimester due to reduced CYP1A2 activity
  • Liver disease — hepatic impairment significantly extends half-life
  • Smoking — CYP1A2 inducers in smoke accelerate clearance (~3h t½)
  • Oral contraceptives — estrogen inhibits CYP1A2, extending t½ by ~30–40%
  • Fluvoxamine / ciprofloxacin — strong CYP1A2 inhibitors; can triple t½
  • High-fat meals — minimal effect; absorption is nearly complete regardless

🛡️ Safety guidelines

  • FDA / EFSA — up to 400 mg/day considered safe for healthy adults
  • Pregnant individuals — ACOG recommends ≤200 mg/day
  • Children / adolescents — no established safe threshold; avoidance advised
  • Anxiety disorders — caffeine exacerbates symptoms; lower limits recommended
  • Hypertension — acute BP elevation of 3–14 mmHg; monitor individually
  • Bedtime caffeine target — the calculator uses 20–50 mg as modeling targets; these are not established clinical thresholds, and individual sensitivity varies substantially
  • Adenosine rebound — caffeine blocks receptors; sleep debt accumulates silently
  • Concentrated supplements — pure caffeine powder & liquid carry overdose risk
Sleep optimization science

🌙 Timing strategies

  • Delayed first coffee — some suggest waiting 60–90 min after waking; cortisol peaks naturally then, but direct evidence for this timing is limited
  • Nap + caffeine — drink espresso before a 20-min nap; caffeine activates as you wake (Reyner & Horne, 1997)
  • Cutoff window — stop caffeine 6–10h before sleep depending on your t½
  • Circadian alignment — late caffeine disrupts melatonin onset by ~40 min (Burke TM et al., 2015)

💤 Sleep hygiene essentials

  • Temperature — bedroom 65–68°F (18–20°C) maximizes deep slow-wave sleep
  • Light exposure — 10,000 lux morning light anchors circadian rhythm
  • Sleep pressure — adenosine builds over 16h of wakefulness; caffeine masks but doesn't repay this debt
  • Consistency — a fixed wake time is more powerful than bedtime for long-term sleep quality
Caffeine-free evening alternatives
🌿 Winding down without caffeine

When it's time to stop caffeine for the evening, water and caffeine-free herbal teas are simple practical alternatives. These contain zero caffeine. Note: decaf coffee and tea usually contain small residual amounts of caffeine (typically 2–15mg per cup) and may not be completely caffeine-free and are a common part of a wind-down routine. Note: specific health claims about herbal ingredients vary in evidence strength — we list these as popular choices, not medical recommendations.

🌼
Chamomile
Contains apigenin — binds to GABA receptors, reducing anxiety and promoting sleepiness.
0 mg caffeine
💜
Lavender
Linalool has mild sedative effects. Shown to reduce heart rate and blood pressure before sleep.
0 mg caffeine
🌱
Valerian Root
May increase GABA levels and shorten sleep onset time in clinical studies.
0 mg caffeine
🍋
Lemon Balm
Rich in rosmarinic acid which inhibits GABA transaminase — naturally calming.
0 mg caffeine
🌸
Passionflower
Clinical trials show sleep quality improvement comparable to low-dose sedatives.
0 mg caffeine
🫚
Ashwagandha
Adaptogen that lowers cortisol. Studies show improved sleep onset after 8 weeks.
0 mg caffeine
💡 Best practice: Start your herbal tea ritual 60–90 minutes before bedtime. The warmth lowers core body temperature — a key physiological sleep trigger. Avoid adding sugar, which can spike blood glucose and delay sleep onset.
Scientific references
[1]
Nehlig A. (2018). Interindividual differences in caffeine metabolism and factors driving caffeine consumption.
Pharmacological Reviews, 70(2), 384–411.
doi:10.1124/pr.117.014407 ↗
[2]
Fredholm BB, et al. (1999). Actions of caffeine in the brain with special reference to factors that contribute to its widespread use.
Pharmacological Reviews, 51(1), 83–133. Foundational paper on caffeine's adenosine receptor antagonism mechanism.
[3]
EFSA Panel on Dietetic Products (2015). Scientific opinion on the safety of caffeine.
EFSA Journal, 13(5), 4102. Establishes the 400 mg/day safe intake threshold for healthy adults.
doi:10.2903/j.efsa.2015.4102 ↗
[4]
Drake C, et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed.
Journal of Clinical Sleep Medicine, 9(11), 1195–1200. Demonstrates measurable sleep disruption even at 6h pre-sleep caffeine intake.
doi:10.5664/jcsm.3170 ↗
[5]
Walker MP. (2017). Why We Sleep: Unlocking the Power of Sleep and Dreams.
Scribner, New York. Comprehensive synthesis of sleep science including caffeine-adenosine dynamics.
[6]
Burke TM, Markwald RR, McHill AW, Chinoy ED, Snider JA, Bessman SC, Jung CM, O'Neill JS, Wright KP Jr. (2015). Effects of caffeine on the human circadian clock in vivo and in vitro.
Science Translational Medicine, 7(305), 305ra146. Demonstrates that evening caffeine delays melatonin onset by ~40 minutes via adenosine receptor antagonism in the circadian master clock.
doi:10.1126/scitranslmed.aac5125 ↗
[7]
Reyner LA & Horne JA. (1997). Suppression of sleepiness in drivers: combination of caffeine with a short nap.
Psychophysiology, 34(6), 721–725. Origin of the evidence-based "nappuccino" strategy combining a brief nap with caffeine intake.
doi:10.1111/j.1469-8986.1997.tb02148.x ↗ · PubMed ↗
[8]
Bonati M, Latini R, Galletti F, Young JF, Tognoni G, Garattini S. (1982). Caffeine disposition after oral doses.
Clinical Pharmacology & Therapeutics, 32(1), 98–106. Classic pharmacokinetic study establishing caffeine's one-compartment first-order elimination model parameters including half-life and volume of distribution in healthy adults.
doi:10.1038/clpt.1982.132 ↗
[9]
Newton R, Broughton LJ, Lind MJ, Morrison PJ, Rogers HJ, Bradbrook ID. (1981). Plasma and salivary pharmacokinetics of caffeine in man.
European Journal of Clinical Pharmacology, 21(1), 45–52. Source for the volume of distribution (Vd ≈ 0.6 L/kg) used to personalize peak concentration estimates by body weight.
doi:10.1007/BF00609587 ↗
[10]
Cappelletti S, Piacentino D, Sani G, Aromatario M. (2015). Caffeine: cognitive and physical performance enhancer or psychoactive drug?
Current Neuropharmacology, 13(1), 71–88. Review covering CYP1A2 genotype-phenotype variability, population-level half-life data, and caffeine's effects on cognition and performance.
doi:10.2174/1570159X13666141210215655 ↗ · PubMed ↗
[11]
Gardiner C, Weakley J, Burke LM, Roach GD, Sargent C, Maniar N, Townshend A, Halson SL. (2023). The effect of caffeine on subsequent sleep: A systematic review and meta-analysis.
Sleep Medicine Reviews, 69, 101764. Meta-analysis of 24 studies showing caffeine reduces total sleep time by 45 min and deep sleep (N3/N4) by 11.4 min.
doi:10.1016/j.smrv.2023.101764 ↗
[12]
Low JJL, Tan BJW, Yi LX, Zhou ZD, Tan EK. (2024). Genetic susceptibility to caffeine intake and metabolism: a systematic review.
Journal of Translational Medicine, 22, 961. Systematic review of 26 studies (n=1,851,428) covering CYP1A2, ADORA2A, AHR, POR, ABCG2, CYP2A6 and other genes affecting caffeine metabolism and habitual consumption. Open access.
doi:10.1186/s12967-024-05737-z ↗
[13]
Heckman MA, Weil J, Gonzalez de Mejia E. (2010). Caffeine (1,3,7-trimethylxanthine) in foods: A comprehensive review on consumption, functionality, safety, and regulatory matters.
Journal of Food Science, 75(3), R77–R87. Widely cited reference for caffeine content across beverages and foods; used to verify drink database values in this calculator.
doi:10.1111/j.1750-3841.2010.01561.x ↗
[14]
Landolt HP, Werth E, Borbély AA, Dijk DJ. (1995). Caffeine intake (200 mg) in the morning affects human sleep and EEG power spectra at night.
Brain Research, 675(1–2), 67–74. Demonstrated that even morning caffeine intake significantly reduces NREM EEG delta activity and slow-wave sleep at night, with effects linked to plasma caffeine concentration. Key reference for the concentration-response relationship used in the estimated caffeine concentration panel.
PubMed ↗
[15]
Landolt HP, Retey JV, Tönz K, et al. (2004). Caffeine attenuates waking and sleep electroencephalographic markers of sleep homeostasis in humans.
Neuropsychopharmacology, 29(10), 1933–1939. Showed caffeine suppresses slow-wave activity (SWA) and sleep homeostatic markers. Alongside the 1995 paper, this establishes the physiological basis for the 0.5–1.5 μg/mL intermediate concentration band used in the concentration panel.
doi:10.1038/sj.npp.1300526 ↗
[16]
Baur DM, Dornbierer DA, Landolt HP. (2024). Concentration-effect relationship of caffeine on EEG delta activity and autonomic variables during sleep.
Journal of Sleep Research, e14173. Randomized, double-blind, crossover study in 21 healthy men. Found that plasma caffeine concentrations above ~7.4 μmol/L (~1.44 μg/mL) were associated with reduced EEG delta activity during NREM sleep. Note: participants received delayed-release caffeine; results may not fully generalize to ordinary coffee consumption in a broad population.
doi:10.1111/jsr.14173 ↗
Important disclaimer
⚠️ Not Medical Advice

This tool is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Caffeine metabolism varies significantly between individuals due to genetics, age, medications, and health conditions not captured by this calculator. Always consult a qualified healthcare provider before making changes to your caffeine intake, especially if you are pregnant, taking medications, or have a medical condition. By using this tool you agree that the creators assume no liability for decisions made based on its output.

Learn more
⏰
Caffeine Cutoff Guide
When exactly should you stop drinking coffee? A full guide personalized by metabolism type.
Read the guide →
🧬
Caffeine Sensitivity & CYP1A2
Why caffeine affects you differently — the genetics of CYP1A2 metabolism explained.
Learn more →
🔬
The Science
20+ peer-reviewed studies on caffeine, sleep, and metabolism — explained in plain language.
Explore research →

The Science

Evidence-based research on caffeine, sleep, and metabolism — drawn from peer-reviewed, high-impact journals.

☕ Caffeine & Sleep

  • Caffeine drunk 6 hours before bed still reduces sleep by 40+ minutes (Drake et al., 2013)
  • Caffeine blocks adenosine receptors — sleep debt accumulates silently
  • Tolerance builds to alertness effects but not to sleep disruption
  • Evening caffeine delays melatonin onset by ~40 minutes (Burke et al., 2015)

🧠 Sleep & Health

  • One bad night makes you 60% more emotionally reactive (Krause et al., 2017)
  • Under 6h sleep raises type 2 diabetes risk by 28%
  • Sleep follows a U-curve — both too little and too much increase cardiovascular risk
  • The brain's glymphatic system clears toxins during deep sleep — caffeine disrupts this
🔬 Read the full science — 20+ studies explained →

Drawn from Nature, BMJ, PNAS, JCSM and other peer-reviewed journals

Caffeine & Sleep Tools

These science-backed calculators to help you understand your relationship with caffeine — from daily safe limits to withdrawal timelines and sensitivity profiling.

🚫
Caffeine Withdrawal Calculator

Thinking of cutting back on caffeine? Enter your current daily intake and when you last had caffeine to see your predicted withdrawal timeline, symptom severity, and a personalized gradual reduction schedule. Based on Juliano & Griffiths (2004) Psychopharmacology.

Typical: 1 coffee = 95mg, espresso = 63mg, energy drink = 80-300mg
⚠️ Predicted withdrawal severity:
Symptoms begin in
—
hours
Peak symptoms at
—
hours
Fully resolved by
—
hours
Expected symptoms:
💡 Gradual reduction schedule (cut 10% every 2 days):
DayTarget daily intakeChange
  • Withdrawal symptoms are temporary and resolve within 2–9 days for most people
  • Gradual reduction (10% every 2 days) minimizes headache and fatigue severity
  • Stay well hydrated — dehydration worsens withdrawal headaches
  • Source: Juliano & Griffiths (2004). Psychopharmacology, 176(1), 1–29
🛡️
Daily Safe Caffeine Limit Calculator

The FDA's 400mg/day guideline applies to healthy adults — but your personal safe limit may be lower based on age, pregnancy, health conditions, and medications. Based on EFSA (2015) and ACOG guidance.

Your personalized daily caffeine limit
— mg/day
    🧬
    Caffeine Sensitivity Quiz

    Not sure whether to select Fast, Normal, or Slow in the main calculator? Answer 6 quick questions to choose your caffeine clearance starting point. Based on Nehlig (2018) Pharmacological Reviews.

    1. How do you feel after ONE standard cup of coffee (95mg)?
    2. Can you drink coffee after 6pm and still fall asleep at your normal time?
    3. How long after your last coffee does it take to feel the alertness fading?
    4. Do you get withdrawal headaches if you skip your usual morning caffeine?
    5. How many cups do you need to feel alert and functional in the morning?
    6. Do you experience anxiety, jitteriness, or heart palpitations from caffeine?
    —
    Estimated half-life:
    💡 Use this result in the main calculator: Go to the Calculator tab and set your Metabolism type to match your result above for a more personalized caffeine cutoff time.
    • This quiz estimates metaboliser type — it is not a genetic test
    • For a definitive result, CYP1A2 genotyping is available through consumer DNA tests
    • Source: Nehlig A. Pharmacological Reviews, 70(2), 384–411 (2018)
    ⚠️ Not medical advice. These tools are for informational and educational purposes only. Consult a qualified healthcare professional before making changes to your caffeine intake, especially if you have a medical condition or are pregnant.

    About CaffeineSleepCalc

    Last updated: August 2026

    Who built this site

    CaffeineSleepCalc was built by two academic researchers in bioengineering and economics, with expertise in biological and chemical engineering and data modeling. The pharmacokinetic model at its core applies first-order elimination kinetics — a standard framework in bioprocess and chemical engineering — to published caffeine-metabolism data. We are independent researchers and health-science enthusiasts, not medical professionals. All calculations are based on peer-reviewed sources cited throughout the site.

    Our mission

    Most caffeine advice online is a single imprecise rule of thumb: "stop coffee after 2pm." As researchers trained in quantitative modeling, we found this unsatisfying. Caffeine metabolism can be estimated with established pharmacokinetic models, yet no free tool was applying them rigorously. We built CaffeineSleepCalc to change that: a pharmacokinetics-based calculator that anyone can use in seconds, for free, with no account required.

    How the calculator works

    The calculator uses a one-compartment, first-order elimination model — the standard pharmacokinetic framework for oral caffeine. The formula is: C(t) = C₀ × e^(−k·t), where k = ln(2) / t½. The calculator offers fast (~3h), typical (~5h), and slow (~8h) clearance scenarios using illustrative half-life assumptions based on published population data from Nehlig (2018) in Pharmacological Reviews, EFSA (2015), and Drake et al. (2013) in the Journal of Clinical Sleep Medicine. These clearance settings are not a genetic test and do not determine an individual's CYP1A2 status.

    Where users select the concentration-based output, the model applies a population-average volume-of-distribution assumption (Vd = 0.6 L/kg; Newton et al., 1981) to estimate — not measure — peak plasma caffeine concentration. Body weight does not affect the caffeine-remaining calculation, and does not predict individual clearance rate or sleep sensitivity. The bedtime caffeine target (20mg or 50mg) is a user-configurable modeling threshold — not a universally established medical safety limit. Individual clearance and sleep response vary substantially due to tolerance, genetics, medications, age, and other factors.

    Model limitations

    • All calculations use population-average parameters — individual results will vary
    • Caffeine absorption begins within 15–45 minutes and peaks at 30–60 minutes; this calculator uses the time of consumption as the start of the decay curve, which is a simplification
    • The model does not account for tolerance, pregnancy, liver disease, drug interactions, or individual genetic variation beyond the three clearance scenarios
    • Food co-ingestion can slow caffeine absorption; this is not modeled
    • Caffeine in the sensitivity quiz is an informal self-assessment to help users choose a starting scenario — it is not a validated clinical instrument

    What we are not

    We are not doctors, pharmacists, or licensed medical professionals. CaffeineSleepCalc is an educational tool, not a medical service. Nothing on this site constitutes medical advice. Always consult a qualified healthcare professional regarding your caffeine intake, especially if you have a medical condition, are pregnant, or take medications that interact with caffeine.

    Scientific references

    All scientific claims on this site are cited with peer-reviewed sources linked to doi.org and PubMed. Our primary references are listed on the main calculator page. We review and update citations periodically. If you identify an error or an outdated reference, please contact us.

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    We welcome feedback, bug reports, and suggestions. Use the or email us directly at:

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    Privacy Policy

    Effective date: January 1, 2026 · Last updated: August 2026

    Your privacy is important to us. This policy explains what information CaffeineSleepCalc collects, how it is used, and your rights under applicable privacy laws including the General Data Protection Regulation (GDPR) for EU/EEA users, the California Consumer Privacy Act (CCPA) for California residents, and other applicable regulations.

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    • No account required. You do not need to register or log in to use the calculator.
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    Terms of Service

    Effective date: January 1, 2026 · Last updated: August 2026

    By accessing or using CaffeineSleepCalc ("the site"), you agree to be bound by these Terms of Service. If you do not agree, please do not use the site.

    1. Use of the site

    • The site is provided for informational and educational purposes only.
    • You must be at least 18 years of age to use this site.
    • You agree not to misuse the site or attempt to disrupt its operation.

    2. Not medical advice

    The content on CaffeineSleepCalc — including all calculations, recommendations, and reference materials — does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for personal health decisions. See our full disclaimer on the main calculator page.

    3. Accuracy of information

    We make reasonable efforts to ensure accuracy, but we do not warrant that the calculator results are complete, error-free, or suitable for your specific circumstances. Caffeine metabolism is highly individual and the model used is based on population averages.

    4. Limitation of liability

    To the fullest extent permitted by law, CaffeineSleepCalc and its creators shall not be liable for any direct, indirect, incidental, or consequential damages arising from your use of, or reliance on, the site or its content.

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