เครื่องคำนวณคาเฟอีน – ปริมาณที่บริโภคต่อวัน
Track your daily caffeine intake and estimate when it will wear off.
วิธีใช้เครื่องคิดเลขนี้
- ป้อนNumber of Drinks
- ป้อนDrink Type
- คลิกปุ่มคำนวณ
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How Caffeine Works in Your Body
Caffeine blocks adenosine receptors in the brain — adenosine is the molecule that makes you feel sleepy as it accumulates during the day. By blocking it, caffeine increases alertness, concentration, and mood. Effects begin within 15–45 minutes of consumption and peak at 1–2 hours.
Caffeine has a half-life of approximately 5–6 hours in healthy adults. This means half the caffeine from a 3 PM coffee is still in your system at 9 PM. This is the primary reason afternoon caffeine disrupts sleep quality even if you can fall asleep.
Caffeine Content by Beverage
Approximate caffeine per serving:
- Espresso (1 oz): 63 mg
- Drip coffee (8 oz): 95–200 mg
- Cold brew (8 oz): 100–200 mg
- Black tea (8 oz): 47 mg
- Green tea (8 oz): 28 mg
- Cola (12 oz): 34 mg
- Energy drink (8 oz): 70–150 mg
- Dark chocolate (1 oz): 12 mg
The FDA recommends a maximum of 400 mg/day for healthy adults — roughly 4 cups of drip coffee.
Caffeine and Sleep
Even moderate caffeine consumption can reduce sleep quality without you noticing. Studies show that 400 mg of caffeine taken 6 hours before bed reduces total sleep time by over 1 hour. The effect on deep sleep (the most restorative phase) is even more pronounced.
Best practice: set a personal caffeine cutoff time. A good rule of thumb: no caffeine after 2 PM (or at least 8–10 hours before planned bedtime). If you are sensitive to caffeine, this window may need to be even earlier.
ตารางปริมาณคาเฟอีน
แหล่งคาเฟอีนทั่วไปและปริมาณโดยประมาณ
| แหล่ง | คาเฟอีนทั่วไป | ความเข้มข้น |
|---|---|---|
| Espresso (1 shot / 30ml) | 63 mg | ~210 mg/100ml |
| Drip coffee (240ml) | 95 mg | ~40 mg/100ml |
| Cold brew (240ml) | 150 mg | ~63 mg/100ml |
| Instant coffee (240ml) | 60 mg | ~25 mg/100ml |
| Latte / Cappuccino (240ml) | 63 mg | ~26 mg/100ml |
| Green tea (240ml) | 28 mg | ~12 mg/100ml |
| Black tea (240ml) | 47 mg | ~20 mg/100ml |
| Cola (355ml) | 34 mg | ~10 mg/100ml |
| Energy drink (250ml) | 80 mg | ~32 mg/100ml |
| Dark chocolate (40g) | 24 mg | ~60 mg/100g |
| Pre-workout (1 serving) | 150–300 mg | varies |
อัปเดตล่าสุด: March 2026
Frequently Asked Questions
How much caffeine is safe per day?
The FDA and EFSA recommend up to 400 mg/day for healthy adults, 200 mg for pregnant women. Adolescents should limit to 100 mg. Individual sensitivity varies widely — some people metabolize caffeine faster (genetics of CYP1A2 enzyme) and tolerate more.
Can you build a tolerance to caffeine?
Yes. Regular consumption leads to tolerance within 1–2 weeks — you need more to achieve the same effect. Withdrawal symptoms (headache, fatigue, irritability) peak 1–2 days after stopping and resolve within a week. A periodic caffeine reset (1–2 weeks off) restores sensitivity.
Does caffeine dehydrate you?
Mildly, at high doses. But the water in coffee and tea more than compensates for the diuretic effect. Regular coffee and tea consumption counts toward daily fluid intake. Only very high caffeine doses (500+ mg) or caffeine pills without water cause meaningful dehydration.