coffee

Brewed Coffee (240ml / 8oz)

Caffeine Half-Life Analysis

For: Fast Metabolizers (Genetic)
95
mg Caffeine
3.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
400
mg Daily Limit

trending_down Caffeine Decay Timeline

How 95mg caffeine clears from your system with a 3.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 95.0 mg
100.0% 		Moderate
After 1 hour 77.9 mg
82.0% 		Moderate
After 2 hours 63.9 mg
67.3% 		Moderate
After 3 hours 52.4 mg
55.2% 		Moderate
After 4 hours 43.0 mg
45.3% 		Minimal
After 5 hours 35.3 mg
37.1% 		Minimal
After 6 hours 29.0 mg
30.5% 		Minimal
After 8 hours 19.5 mg
20.5% 		Minimal
After 10 hours 13.1 mg
13.8% 		Minimal
After 12 hours 8.8 mg
9.3% 		Cleared
After 16 hours 4.0 mg
4.2% 		Cleared
After 20 hours 1.8 mg
1.9% 		Cleared
After 24 hours 0.8 mg
0.9% 		Cleared

health_and_safety Health Insights for Fast Metabolizers (Genetic)

ℹ️ Health Note

Approximately 10% of the population has CYP1A2*1A genotype, making them 'fast metabolizers'. These individuals can drink coffee late and still fall asleep easily.

Daily Limit Calculation

  • • Recommended daily limit: 400mg of caffeine
  • • Caffeine per serving: 95mg
  • • Servings until limit: 4.2 servings

You may tolerate higher caffeine doses, but cardiovascular risks remain. Don't exceed 400mg/day.

Sleep Quality Impact

Caffeine blocks adenosine receptors in the brain, preventing the buildup of sleep pressure. Even when you don't feel "wired," residual caffeine can reduce deep sleep quality by up to 20%.

>100mg
May disrupt sleep
50-100mg
Reduced deep sleep
<50mg
Minimal impact

science How Caffeine Half-Life Works

Half-life is the time required for the body to eliminate 50% of a substance. For caffeine, this primarily occurs in the liver through the CYP1A2 enzyme system.

With a half-life of 3.5 hours for fast metabolizers (genetic), caffeine follows exponential decay:

  • After 3.5 hours: 50% remains (47.5mg)
  • After 7.0 hours: 25% remains (23.75mg)
  • After 10.5 hours: 12.5% remains (11.875mg)
  • After 14.0 hours: 6.25% remains (5.9375mg)

The fast metabolizers (genetic) category has a faster metabolism compared to healthy adults (5 hours baseline). Approximately 10% of the population has CYP1A2*1A genotype, making them 'fast metabolizers'. These individuals can drink coffee late and still fall asleep easily.

Compare Other Drinks

Espresso (30ml / 1oz shot) 63mg Red Bull (250ml / 8.4oz) 80mg Monster Energy (473ml / 16oz) 160mg Green Tea (240ml / 8oz) 28mg

Compare Conditions

Healthy Adult 5.0h Smokers 3.0h Pregnancy 10.5h Birth Control Users 7.5h Liver Impairment 12.0h Elderly (65+) 6.5h

Related Tools

local_cafe Full Caffeine Calculator hourglass_bottom Caffeine Cut-off Time bedtime Sleep Cycle Calculator

About Brewed Coffee (240ml / 8oz)

Standard drip-brewed coffee

Note: Caffeine can range from 70-140mg depending on brewing method and bean origin

help Frequently Asked Questions

How long does Brewed Coffee (240ml / 8oz) caffeine last for fast metabolizers (genetic)?

For fast metabolizers (genetic), the caffeine half-life is approximately 3.5 hours. This means that 95mg of caffeine from Brewed Coffee (240ml / 8oz) will take about 3.5 hours to reduce to 48mg, and 7.0 hours to drop to 24mg. Full clearance (below 10mg) takes approximately 11.4 hours.

When should I stop drinking Brewed Coffee (240ml / 8oz) to sleep well?

If you plan to sleep at 10 PM, you should consume your last Brewed Coffee (240ml / 8oz) by any time - caffeine level is low. This allows approximately sufficient hours for caffeine levels to drop below the sleep disruption threshold of 100mg.

How does being in the 'Fast Metabolizers (Genetic)' category affect caffeine metabolism?

Approximately 10% of the population has CYP1A2*1A genotype, making them 'fast metabolizers'. These individuals can drink coffee late and still fall asleep easily. You may tolerate higher caffeine doses, but cardiovascular risks remain. Don't exceed 400mg/day.