Caffeine Content Calculator

Dose Summary

{{ format(total_mg) }} mg

{{ typeLabel }} · {{ size_value }} {{ size_unit }} (≈ {{ Math.round(size_ml) }} mL)

{{ guidelineLabel }} {{ dose_mg_per_kg.toFixed(2) }} mg/kg {{ percent_limit.toFixed(0) }}% of daily Active now {{ Math.round(active_now_mg) }} mg

Drink type:

Size:

Strength factor: ×

Caffeine per serving: mg

Body weight:

Time since consumed:

min

Guideline:

Half-life:

Absorption peak:

min

Look-ahead window:

Field	Value	Copy
Drink	{{ typeLabel }}
Size	{{ size_value }} {{ size_unit }} ({{ Math.round(size_ml) }} mL)
Strength	{{ strength_factor.toFixed(2) }} ×
Total caffeine (mg)	{{ total_mg.toFixed(2) }}
mg/mL	{{ mg_per_ml.toFixed(2) }}
mg/100 mL	{{ mg_per_100ml.toFixed(1) }}
mg/8 fl oz	{{ mg_per_8oz.toFixed(0) }}
Dose (mg/kg)	{{ dose_mg_per_kg>0 ? dose_mg_per_kg.toFixed(2) : '—' }}
Daily limit (mg)	{{ daily_limit_mg }}
Percent of guideline (%)	{{ percent_limit.toFixed(0) }}
Active now (mg)	{{ active_now_mg.toFixed(2) }}
Half-life (h)	{{ half_life_h.toFixed(2) }}
Absorption peak (min)	{{ Math.round(absorb_min) }}
Look‑ahead (h)	{{ Math.round(lookahead_h) }}

Tags: Education , Nutrition

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Caffeine dose is the amount of stimulant in a serving and it reflects both drink volume and brewing strength. A caffeine content calculator turns everyday servings into clear totals you can compare with common guidance and with your own tolerance over a typical day.

Enter a drink type and serving size, then read the total in milligrams along with density per volume and dose per body weight if you add weight. You can also enter the time since you drank it so you see an estimate of how much remains in your body now, which helps you pace energy earlier and sleep later without trial and error.

For example, a twelve ounce brewed coffee works out to roughly one hundred forty two milligrams at a neutral strength, which is about one quarter of a typical adult day. If you check again after a few hours the estimate tapers to about half as the body clears it, so you can decide whether another cup makes sense.

Results are estimates rather than diagnoses and people vary in sensitivity. Pregnancy changes limits and stronger mixes can run high, so treat high readings with care. This tool provides informational estimates and does not substitute professional advice.

Technical Details:

The quantities of interest are the total caffeine in milligrams for a serving, the concentration per milliliter and per one hundred milliliters, the equivalent per eight fluid ounces, the dose per kilogram of body mass, and the share of a daily guideline. Time since consumption is used to estimate the amount still active.

Total caffeine is computed from serving volume and a drink‑type density that reflects typical preparation. When weight is provided the calculator reports milligrams per kilogram to make doses comparable across people. A simple absorption followed by first‑order elimination is used to approximate the active amount after a given number of minutes.

Guideline bands are provided for context only. Adult limit is four hundred milligrams per day, pregnancy two hundred per day, and teen roughly one hundred per day. Alerts surface when a single serving is very high, when a dose per kilogram is strong, or when a serving alone would meet or exceed a daily guideline.

\begin{matrix} D & = & V / 100 \times C \times S \\ (V = milliliters, C = milligrams per 100 milliliters, S = strength factor) \\ D & = & entered milligrams when using a custom serving \end{matrix}

\begin{matrix} Λ & = & \frac{\ln (2)}{h \times 60} \\ A (t) & = & piecewise {if t < t \end{matrix}

_peak: D× tt_peak , if t≥t_peak: D× e -Λ(t-t_peak) }

Symbols and units used in formulas
Symbol	Meaning	Unit/Datatype	Source
$D$	Total caffeine in serving	mg	Derived
$V$	Serving volume	mL	Input
$C$	Density per 100 milliliters	mg/100 mL	Drink type
$S$	Strength factor	number	Input
$Λ$	Elimination rate constant	min⁻¹	Derived
$h$	Half life	hours	Input
$t$	Minutes since consumption	min	Input
$t$ _peak	Absorption peak time	min	Input
mg/kg	Dose per kilogram of body mass	mg/kg	Derived
Guideline %	Share of selected daily limit	%	Derived

Worked example

Brewed coffee, twelve fluid ounces, neutral strength. Drink density is forty milligrams per one hundred milliliters, and volume is about three hundred fifty five milliliters.

\begin{matrix} D & = & (355 / 100) \times 40 = 141.95 \approx 142 mg \\ Guideline % & = & 142 / 400 \times 100 \approx 36 % (adult) \\ mg/kg & = & 142 / 70 \approx 2.03 mg/kg \\ Active at 45 min & = & 142 mg (at peak) \\ Active 5 h after peak & = & 142 \times 2^{- 1} = 71 mg \end{matrix}

Reading: a single cup is a moderate serving for an adult and would be a strong dose per kilogram only for very low body mass.

Alert thresholds and interpretations
Alert	Lower Bound	Upper Bound	Interpretation	Action Cue
High single dose	200 mg	∞	Single serving is large.	Consider a smaller size next time.
Strong mg/kg	3.00	< 6.00	Notable per‑kilogram dose.	Add time before another serving.
Very strong mg/kg	6.00	∞	High per‑kilogram dose.	Avoid stacking servings.
Exceeds daily guideline	100 %	∞	Single serving meets a full day.	Switch to decaf or pause.

Units, precision, and rounding

Decimal separator is a dot and numbers are rounded to displayed places.
Totals show two decimals; milligrams per milliliter two; per one hundred milliliters one; per eight ounces zero; percentages as whole numbers.
Milliliter conversions use 29.5735295625 per fluid ounce and 236.5882365 for eight ounces.

Validation and bounds

Inputs with limits and validation
Field	Type	Min	Max	Step/Pattern	Notes
Drink type	select	—	—	enumerated	Sets density and default volume.
Size value	number	0	—	0.1	Units: milliliters or fluid ounces.
Strength factor	number	0.1	—	0.05	Applied to density for non‑custom types.
Custom milligrams	number	0	—	1	Overrides density when using a custom serving.
Body weight	number	0	—	0.1	Units: kilograms or pounds.
Time since consumed	number	0	—	1	Minutes since the serving.
Half life	number	0.1	—	0.1	Hours to halve the active amount.
Absorption peak	number	0	—	1	Minutes to reach peak.
Look‑ahead window	number	6	—	1	Hours plotted for the timeline.
Guideline	select	—	—	adult / pregnancy / teen	Daily limits: 400, 200, about 100.

Constants and drink profiles

Conversion constants and drink density presets
Constant / Type	Value	Unit / Notes
Fluid ounce to milliliter	29.5735295625	mL per fluid ounce
Eight fluid ounces	236.5882365	mL
Pound to kilogram	0.45359237	kg per lb
Adult daily guideline	400	mg
Pregnancy daily guideline	200	mg
Teen daily guideline	≈ 100	mg
Brewed coffee (drip)	40	mg/100 mL, default 355 mL
Espresso	212	mg/100 mL, default 30 mL
Cold brew coffee	60	mg/100 mL, default 355 mL
Instant coffee (prepared)	30	mg/100 mL, default 240 mL
Americano	25	mg/100 mL, default 355 mL
Latte	18	mg/100 mL, default 355 mL
Cappuccino	40	mg/100 mL, default 180 mL
Flat white	52	mg/100 mL, default 240 mL
Mocha	30	mg/100 mL, default 355 mL
Espresso macchiato	110	mg/100 mL, default 60 mL
Turkish coffee	80	mg/100 mL, default 100 mL
Iced coffee	30	mg/100 mL, default 355 mL
Nitro cold brew	65	mg/100 mL, default 473 mL
Black tea	20	mg/100 mL, default 240 mL
Green tea	12	mg/100 mL, default 240 mL
Oolong tea	16	mg/100 mL, default 240 mL
White tea	10	mg/100 mL, default 240 mL
Chai tea (brewed)	20	mg/100 mL, default 240 mL
Iced black tea	18	mg/100 mL, default 355 mL
Iced green tea	10	mg/100 mL, default 355 mL
Yerba mate (brew)	30	mg/100 mL, default 240 mL
Matcha (prepared)	28	mg/100 mL, default 240 mL
Energy drink (typical)	32	mg/100 mL, default 250 mL
Energy drink (strong)	40	mg/100 mL, default 473 mL
Energy shot	350	mg/100 mL, default 57 mL
Caffeinated sparkling water	10	mg/100 mL, default 355 mL
Cola soda	10	mg/100 mL, default 355 mL
Guaraná soda	12	mg/100 mL, default 355 mL
Kombucha	8	mg/100 mL, default 355 mL
Chocolate milk (cold)	2	mg/100 mL, default 240 mL
Hot chocolate / cocoa	2	mg/100 mL, default 240 mL
Decaf coffee	2	mg/100 mL, default 240 mL
Decaf tea	1	mg/100 mL, default 240 mL
Thai iced tea	12	mg/100 mL, default 350 mL
Coffee pod (prepared)	33	mg/100 mL, default 240 mL

I/O and formats

Inputs and outputs
Input	Accepted Families	Output	Encoding/Precision	Rounding
Numbers and selections	Drink type, size, strength, weight, time, half life, absorption, window, guideline	Metrics table	Two to zero decimals per metric	Nearest at shown places
Copy or download	CSV, JSON	Tabular or structured payload	UTF‑8 text	As displayed for metrics
Timeline	Sampled hours	Hours versus milligrams	Quarter hour minimum step	Two decimals in samples

Networking and storage

All calculations run in the browser and no data is transmitted to a server.
The timeline relies on a charting layer; if it cannot load, metrics still compute.

Assumptions and limitations

Drink densities are typical values and not brand specific.
Strength factor scales density linearly.
Absorption increases linearly until the stated peak.
Elimination follows a constant half life with first order behavior.
Single serving modeling only; multiple servings are not stacked.
Body weight is optional; without it per kilogram is omitted.
Daily guideline is a comparison aid, not a prescription.
Heads‑up Rounding can slightly change category edges.
Very small half lives are clamped to a sensible minimum.
Units must be entered consistently to keep results comparable.

Edge cases and error sources

Zero or negative sizes produce zero totals.
Weight of zero suppresses per kilogram reporting.
Extremely large strengths inflate all downstream measures.
Very long windows show near zero tails due to rounding.
Minute to hour conversions introduce small rounding drift.
Display rounding differs from internal values used in JSON.
Copying single cells exports the rounded value only.
Switching units resets size to the type default.
Timeline sampling step adjusts with window length.
Non numeric inputs are treated as zero where applicable.
Percent of guideline divides by at least one to avoid zero.
Tooltips and timeline require browser features that may be disabled.

Privacy & compliance

No data is transmitted or stored server‑side. Outputs support personal planning only and do not constitute medical advice.

How‑to · Step‑by‑Step Guide

Estimate caffeine dose and the active amount over time for a single serving.

Select a drink type required.
Enter the serving size and choose the unit required.
Adjust the strength factor if your brew is weaker or stronger.
Optionally enter body weight for dose per kilogram.
Enter minutes since consumption to estimate what remains active now.
Pick a daily guideline and set half life and absorption peak if you wish.

Example: Espresso, sixty milliliters, strength one, weight seventy kilograms, forty five minutes since consumption, half life five hours.

If results look implausible, confirm units and strength.
Warning Very high single servings can trigger multiple alerts.

FAQ

Is my data stored?

No. Calculations happen in your browser and nothing is sent to a server or saved remotely.

Sensitive entries do not leave your device.

How accurate is the half life estimate?

It is a simple first order model with a user set half life and a linear rise to a peak. It is a helpful guide, not a clinical measure.

Change half life to fit your experience.

Which units can I use?

Milliliters and fluid ounces for size, kilograms and pounds for weight. Conversions use fixed factors shown above.

All totals convert internally to milliliters and kilograms.

Can I enter a custom serving?

Yes. Choose the custom option and type the total milligrams for the serving when you know it from packaging or lab data.

Strength does not apply to custom entries.

What does “borderline” mean?

Values near alert thresholds can change with rounding. Treat readings around the line as guidance and prefer a margin of safety.

Rerun with the nearest smaller size to compare.

Why does the timeline sometimes not appear?

The chart depends on a display layer. If it cannot load, the metrics still compute and you can copy results as text.

Reload the page or check network settings.

How do I compare different drinks?

Switch the type and keep size constant to compare concentrations. For fair dose comparisons, also enter body weight.

Use per kilogram to normalize across people.

Troubleshooting

Results are zero: confirm size is above zero.
Per kilogram is blank: enter a nonzero weight.
Alerts look wrong: check units and strength.
Timeline missing: the chart layer may not be available.
Copy shows rounded values: use JSON for full precision.
Unexpected resets: changing type resets the default size.

Entered values must be numeric. Non numeric text is treated as zero and results will be suppressed or misleading.

Advanced Tips

Tip Use the same unit every time to keep runs comparable.
Tip Nudge strength up or down to match your usual brew.
Tip Shorten the window when you want detail near the peak.
Tip Keep half life consistent across tests to compare days.
Tip Use per kilogram to compare across different body weights.
Tip Copy CSV for quick sharing and JSON for downstream tools.

Glossary

Caffeine dose: Total stimulant amount in a serving measured in milligrams.
Concentration: Amount per milliliter or per one hundred milliliters.
Half life: Time for the active amount to reduce by half.
Absorption peak: Time from drinking to the maximum active amount.
Dose per kilogram: Milligrams divided by body mass in kilograms.
Guideline percent: Serving share of the selected daily limit.