How long does caffeine stay in your system?

Caffeine has a half-life of roughly 5 hours for the average adult. This means 50% of the caffeine remains in your blood 5 hours after consumption. It can take over 10 hours to clear the 'sleep threshold' of 50mg.

When should I stop drinking coffee to sleep by 11 PM?

For an average metabolism, you should generally stop caffeine intake 8-10 hours before bed. However, this depends on the dosage (e.g., Espresso vs. Venti Latte). Use our caffeine calculator to get your exact personalized cutoff time.

Is 200mg of caffeine a lot?

Yes. 200mg is equivalent to a strong 12oz coffee or two espresso shots. Research shows this amount can disrupt deep sleep even if consumed 6 hours before bed.

How much caffeine is in a Starbucks Grande Latte?

A Starbucks Grande (16oz) Latte contains approximately 150mg of caffeine. This can take 8-10 hours to drop below the 50mg sleep threshold for most adults.

Does Monster Energy have more caffeine than coffee?

A 16oz Monster Energy drink contains about 160mg of caffeine, which is comparable to a Grande coffee from Starbucks. However, the caffeine-to-volume ratio is lower than espresso or cold brew.

Caffeine Stacker

Track your caffeine intake · Know when you can sleep

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50mg sleep threshold

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Common Caffeine Content Database

Caffeine levels in popular drinks and their impact on sleep quality

Drink Name	Size	Caffeine (mg)	Sleep Impact
Starbucks Grande Latte	16 oz	150 mg	High
Monster Energy	16 oz	160 mg	High
Red Bull	8.4 oz	80 mg	Moderate
Espresso Shot	1 oz	63 mg	Moderate
Drip Coffee (Standard)	8 oz	95 mg	Moderate
Cold Brew	12 oz	155 mg	High
Black Tea	8 oz	47 mg	Low
Coke / Pepsi	12 oz	34 mg	Low
Green Tea	8 oz	28 mg	Low

☕ Franchise Coffee Size Guide

Small / Short

8 oz · 1 shot

Medium / Tall

12 oz · 1 shot

Large / Grande

16 oz · 2 shots

XL / Venti

20 oz · 2-3 shots

1 Why the "50mg" Sleep Threshold?

You might wonder: "Why can't I just wait until it hits 0mg?"

In reality, waiting for caffeine to completely leave your system would take over 24 hours! However, sleep studies indicate you don't need to be at zero.

The Logic: 50mg is roughly the amount in a cup of black tea or half a shot of espresso. For most people, this residual amount is low enough for the brain's adenosine receptors to initiate natural sleep pressure.

The Risk: Levels above 100mg at bedtime are clinically proven to increase sleep latency (time to fall asleep) and reduce total sleep time.

2 The "Half-Life" Trap

"I stopped drinking coffee at 2 PM, so why am I awake at midnight?"

This is the most common misconception. Caffeine has a half-life of roughly 5 hours for the average adult.

The Math: If you drink a large 200mg coffee at 4 PM:

→ 9 PM: 100mg still in your blood
→ Midnight: ~70mg remaining

⚠️ That 70mg at midnight is biologically equivalent to taking a shot of espresso right before bed.

The "Buzz" vs. The Blood: The mental alertness (the "buzz") often fades faster than the chemical elimination. You might feel tired, but your body is still chemically wired.

Individual metabolism varies based on genetics (CYP1A2 gene), age, medications, smoking status, and pregnancy. This calculator provides estimates for educational purposes.

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Algorithm Last Updated: December 2025

Based on pharmacokinetics research regarding adenosine receptors, half-life elimination curves, and deep sleep cycles (SWS). We use a safe sleep threshold of 50mg to ensure quality rest. Caffeine metabolism follows first-order kinetics with an average half-life of 5 hours (range: 3-7 hours depending on individual factors).