Is Caffeine Clock free?

Yes. Free, no signup, no ads, no data collection. Runs entirely in your browser.

Does Caffeine Clock upload my data?

No. All processing happens client-side in your browser. Nothing is uploaded to a server.

Who built Caffeine Clock?

Kesava (https://iamkesava.com), part of the Kami Studios little tools collection at https://tools.iamkesava.com.

How does the Caffeine Clock calculate when coffee wears off?

Caffeine has a half-life of about 5–6 hours in healthy adults. The clock tracks how much caffeine remains in your system over time based on your intake time, dose, and personal sensitivity.

Can I enter multiple coffees or other drinks?

Yes. Add each drink with its time and caffeine content. The clock sums their curves and shows when your combined caffeine load drops below a threshold you choose.

Is the result medically accurate?

It's a useful approximation based on standard pharmacokinetic models, but individual metabolism varies by liver enzymes, age, and medications. Treat it as a guide, not a prescription.

Does it consider espresso vs. drip vs. energy drinks?

Yes. The intake form includes preset caffeine amounts for common drinks (espresso ~65 mg, drip ~100 mg, energy drink ~80–150 mg) and lets you enter a custom amount.

Caffeine Clock

When will your coffee actually wear off?

Caffeine in system — today

12am3am6am9am12pm3pm6pm9pm12am

Now Bedtime

☕ 08:00 · Drip coffee (96mg)

Right now

active caffeine

At bedtime

Sleep is safe

12mg active · under 50mg at bedtime

Last safe coffee

4:19 PM

still time — have one if you need

Fully cleared (below 5%)

5:40 AM

About this tool

How does the Caffeine Clock calculate when coffee wears off?: Caffeine has a half-life of about 5–6 hours in healthy adults. The clock tracks how much caffeine remains in your system over time based on your intake time, dose, and personal sensitivity.
Can I enter multiple coffees or other drinks?: Yes. Add each drink with its time and caffeine content. The clock sums their curves and shows when your combined caffeine load drops below a threshold you choose.
Is the result medically accurate?: It's a useful approximation based on standard pharmacokinetic models, but individual metabolism varies by liver enzymes, age, and medications. Treat it as a guide, not a prescription.
Does it consider espresso vs. drip vs. energy drinks?: Yes. The intake form includes preset caffeine amounts for common drinks (espresso ~65 mg, drip ~100 mg, energy drink ~80–150 mg) and lets you enter a custom amount.