Preselected calculator · substanceDrug Half Life Elimination Calculator
Drug Half Life Elimination Calculator
Caffeine.
Caffeine is applied to the real calculator input below. Review the visible assumptions and source scope, then adjust any details that differ from your situation.
Preselected valueCaffeineIllustrate one-compartment decay from an exact product half-life while blocking dosing, safety and drug-test clearance claims. Sensitive inputs stay in your browser. Verify important decisions with a qualified professional.
Browse substancecannabisnicotinecaffeineamphetaminecocaineopioidbenzodiazepinealcoholthcmdmamethamphetaminepsilocybinkratomgeneral
Preselected reference valueCaffeineThis value is applied to the real calculator input. Adjust the remaining assumptions and verify the visible source before relying on the result.
Your result
6.25%
The displayed fraction is the one-compartment equation 0.5^(elapsed ÷ half-life). FDA labeling distinguishes effective and terminal half-life and may describe active metabolites, nonlinear elimination and population variability. Review note: Verify the exact product half-life.
Why this result
Medication / substancecaffeine
Half-life entered12 hoursUnverified general value
Elapsed time48 hours
Half-lives elapsed4
Mathematical parent-drug fraction6.25%Not a measured blood level, pharmacologic effect, safety threshold or test result
Dosing contextSingle-dose illustration
Metabolite / kinetics checkNot checkedSimple exponential decay is not enough
Intended decisionEducation only
Five half-lives60 hours · 3.125% mathematical fraction
Seven half-lives84 hours · 0.78125% mathematical fraction
Safety screenNo overdose or severe symptom selected
Read before relying
Context matters.
- Do not use a half-life multiple to decide when to stop or repeat medicine, drive, breastfeed, undergo a procedure or assume an overdose is safe.
- The exact formulation, dose, repeated dosing, kidney or liver function, age, interactions, active metabolites and effective versus terminal half-life can materially change exposure.
- A predicted fraction cannot tell whether a drug test will be negative; test type, analyte, cutoff and specimen collection control the reported result.
Rule set 2.0.0
Source & calculation QA reviewedSources & scope
The calculation guide and this source trail show what the result means, where the rule came from and when it was last reviewed. This is source-and-calculation QA, not a claim of medical, legal, tax or other professional review; time-sensitive decisions still belong with the linked authority.
U.S. Food and Drug Administration · SRC-FDA-PK-LABEL-001Clinical Pharmacology Section of Labeling — effective and terminal half-life contextSource retrieved 2026-08-20FTC · SRC-FTC-HEALTH-001Mobile Health Apps Interactive ToolSource retrieved 2026-08-19
JurisdictionPharmacokinetic education — exact FDA prescribing-information half-life; never a dosing, safety or test-clearance result
Last reviewed2026-08-20
Next review due2027-02-20
Review scopeCalcSpan source & calculation QA
PrivacySensitive input stays local