Caffeine limit and sleep cut-off time calculator

This caffeine limit and sleep cut-off time calculator gives you two practical numbers: a daily caffeine cap that scales to your body weight and context, and a latest last-cup time that respects caffeine half-life and your target bedtime. Keeping text and inputs in clean straight lines helps on mobile, and the outputs use plain language you can act on today for better sleep hygiene and steadier energy.

Why a daily cap matters: caffeine helps alertness and training, but too much raises anxiety, reflux, palpitations and fragmented sleep. A conservative starting point is about three milligrams per kilogram of body weight. The planner also applies sensible ceilings: many healthy adults stay under four hundred milligrams per day, pregnancy guidance often suggests two hundred milligrams or less. Because brew strength and brands vary, treat any chart as a starting estimate and adjust based on your own labels and how you feel.

Half-life is the key to the cut-off. After each half-life, the amount in your body halves again. If you want only a small fraction remaining at lights out, count backward from your bedtime by two to four half-lives. The standard options reflect common practice: two half-lives for a practical, afternoon-friendly curfew; three for stricter protection; and four for those who prefer the cleanest nights. Half-life itself varies with genetics, smoking status, medications and pregnancy. If you clear caffeine slowly, select a longer half-life; if it fades quickly for you, choose a shorter one.

Useful drink estimates you can edit: a single espresso shot often lands around sixty to seventy milligrams; a small filter coffee is roughly ninety to one hundred; a mug of black tea comes in near forty to fifty; a can of cola sits around thirty; a small energy drink is often about eighty. Pre-workout formulas vary dramatically—some exceed two hundred milligrams per scoop—so check your tub and include that amount in your daily total. Chocolate, iced tea and some pain relievers add smaller amounts that can still nudge sleep later when taken in the evening.

How to use the output: front-load more of your intake in the first half of the day, then taper. Two earlier, smaller top-ups usually beat a single late spike for productivity without harming sleep. On stressful days, arousal is already high—dropping your cap by one or two hundred milligrams and moving the cut-off earlier often feels better. If you train late, keep servings modest and finish them well before the curfew. Many people notice less sleep latency and fewer night awakenings after shifting the last cup just one to three hours earlier.

Make the basics support you: open the morning with bright outdoor light, leave a buffer of at least an hour before your first coffee, hydrate across the day, and protect a short wind-down routine at night. Pair caffeinated drinks with food if you get jitters, and avoid stacking energy drinks with pre-workout. Track what you actually drink for a week—shots, mugs, cans—and compare to the cap. Small, consistent changes compound faster than one-off extremes.

Important cautions: this planner provides general information and cannot account for every medical condition. Pregnancy usually slows caffeine clearance; many guidelines suggest two hundred milligrams per day or less. People with anxiety disorders, arrhythmias, hypertension, reflux or sleep disorders often do better with a lower cap and an earlier cut-off. Children and teens should follow pediatric guidance rather than adult limits. If you experience palpitations, tremor, nausea, headaches or persistent insomnia, reduce intake and consult a clinician.

Search phrases that can help you learn more include caffeine half-life timing, last coffee before bed, caffeine during pregnancy, daily caffeine limit, espresso milligrams per shot, energy drink caffeine per can and sleep hygiene habits. Use them to cross-check your plan and tune your daily routine without overthinking the details.

FDA overview of typical caffeine amounts · EFSA scientific opinion on caffeine safety · ACOG guidance for pregnancy and caffeine · Review of caffeine half-life and sleep effects