When you go to bed,how many cups of coffeeare still in your system?
Enter coffee time and bedtime, then estimate in 3 seconds how much caffeine is left before sleep.
Got an idea? Smash the button above.
Useful context before you rely on the number
How does this work?
We use the coffee times, cup count, and planned bedtime you enter to estimate how much caffeine may still be in your system before sleep.
Caffeine usually starts to kick in about 15-45 minutes after you drink it, and its half-life is roughly 5-6 hours. In plain terms: after 5-6 hours, around half of it may still be hanging around.
To make the number easier to understand, we turn the estimate into "cups of coffee left." It's not a lab test, just a small tool for reading the general trend.
Why can afternoon coffee affect bedtime?
Caffeine does not wait until bedtime to start fading. A cup in the afternoon keeps declining over the next several hours.
If you are sensitive to caffeine, a later cup can leave your body feeling a little switched on at night, even when you feel mentally tired.
This tool is not here to tell you to quit coffee. It helps you see your last cup on a timeline.
How to read "cups left"
Around 0.2 cups left usually means most of the caffeine has already faded.
Around 0.5 cups left means there's still a noticeable little trace before bed.
Above 0.8 cups left is like having most of a cup's caffeine still with you at bedtime. If you're sensitive to caffeine, that could already be enough to affect sleep.
Let your own body be the baseline
The same cup can let one person sleep just fine and leave another staring at the ceiling at 2 AM.
Coffee strength, cup size, your body, schedule, stress, medication, pregnancy, or breastfeeding can all change how it actually feels.
Use this as a bedtime reference, not medical advice. If you often have heart palpitations, anxiety, insomnia, or you're taking medication, play it more conservatively and consider talking to a professional.
About this small tool
Coffee Sleep is a lightweight caffeine estimator. It is meant for logging when you had coffee, then checking roughly how much caffeine may remain at your planned bedtime.
It is built for everyday use: workdays, study days, coffee lovers, and anyone trying to understand the effect of a later cup.
We keep the tool open, quick, and account-free. The result is an estimate, not a medical conclusion.
Where did coffee come from?
Coffee has been traveling for centuries.
Wild coffee plants are commonly traced back to Ethiopia. Later, coffee crossed the Red Sea to Yemen, where people began growing it, brewing it, and turning it into a culture.
From the Arab world, it moved into Europe. Through ports, caravans, and coffeehouses, it slowly became the first cup of the day for many people.
A cup of coffee has come a long way
A coffee bean is actually the seed of a coffee tree.
It sprouts in soil, is cared for, transplanted, and grown into a tree. Only years later does it produce coffee cherries. The ripe fruit is picked, processed, dried, roasted, ground, and finally becomes the cup in your hand.
So today's coffee is more than a short burst of alertness. It has passed through land, time, weather, farmers, roasters, and many hands.
Of course, by bedtime, it should also know how to behave: when it's time to clock out, no overtime.
