Try using our caffeine calculator to estimate caffeine intake and its potential overdose effects on your body using “Caffeine Dosage (mg/kg) = Total Caffeine Consumed (mg) / Body Weight (kg)” formula.
A person weighing 70 kg who consumes two cups of coffee (200 mg caffeine) and a can of energy drink (80 mg caffeine) can use a caffeine overdose calculator to determine:
- Total caffeine intake: 280 mg
- Caffeine per kg of body weight: 4 mg/kg
- Estimated time until caffeine leaves the system: ~14 hours
Caffeine Calculator
| Beverage Type | Quantity | Caffeine Content | Body Weight | Total Intake | Caffeine per kg | Time to Metabolize |
|---|---|---|---|---|---|---|
| Coffee | 2 cups | 190 mg | 70 kg | 190 mg | 2.71 mg/kg | ~10 hours |
| Energy Drink | 1 can | 80 mg | 60 kg | 80 mg | 1.33 mg/kg | ~5 hours |
| Green Tea | 3 cups | 75 mg | 80 kg | 75 mg | 0.94 mg/kg | ~4 hours |
| Espresso | 2 shots | 126 mg | 65 kg | 126 mg | 1.94 mg/kg | ~7 hours |
| Cola | 2 cans | 70 mg | 75 kg | 70 mg | 0.93 mg/kg | ~4 hours |
| Black Tea | 3 cups | 90 mg | 70 kg | 90 mg | 1.29 mg/kg | ~6 hours |
| Iced Coffee | 16 oz | 200 mg | 80 kg | 200 mg | 2.50 mg/kg | ~10 hours |
| Matcha | 1 serving (1 tsp) | 70 mg | 70 kg | 70 mg | 1.00 mg/kg | ~6 hours |
| Dark Chocolate | 100 g | 50 mg | 75 kg | 50 mg | 0.67 mg/kg | ~4 hours |
| Caffeinated Snack Bar | 1 bar | 100 mg | 70 kg | 100 mg | 1.43 mg/kg | ~5 hours |
| Yerba Mate | 1 cup | 85 mg | 75 kg | 85 mg | 1.13 mg/kg | ~6 hours |
| Caffeine Pill | – | Varies (200-300 mg) | – | – | – | – |
Caffeine Overdose Calculation Formula
The formula for calculating potential caffeine overdose risk is:
Caffeine Dosage (mg/kg) = Total Caffeine Consumed (mg) / Body Weight (kg)A dosage exceeding 15 mg/kg is considered potentially dangerous.
A person weighing 60 kg who consumes:
- 3 cups of coffee (300 mg)
- 2 energy drinks (160 mg)
- 1 caffeine pill (200 mg)
Total caffeine intake: 660 mg
Caffeine Dosage = 660 mg / 60 kg = 11 mg/kgWhile this dosage is high, it’s below the 15 mg/kg threshold.
Recommended Caffeine Intake
| Age Group | Recommended Daily Limit | Caffeine per kg (mg) | Example Body Weight (kg) | Total Caffeine Limit (mg) |
|---|---|---|---|---|
| Adults | Up to 400 mg | 2.5 – 4 | 70 | 175 – 280 |
| Pregnant women | 200 mg or less | 1.5 – 3 | 70 | 105 – 210 |
| Adolescents (12-18) | < 100 mg | 1.5 – 2.5 | 60 | 90 – 150 |
| Children (< 12) | Not recommended | < 2.5 | 30 | < 75 |
| Athletes | Up to 600 mg | 3 – 9 | 80 | 240 – 720 |
| Individuals with Sensitivity | < 200 mg | < 3 | 50 | < 150 |
How do you calculate how much caffeine you can have?
To determine your personal caffeine limit, consider the following steps:
Establish a baseline: Start with the recommended limit of 400 mg for adults.
Adjust for body weight: A general rule is 3-6 mg per kg of body weight.
Consider individual factors: Tolerance, sensitivity, and health conditions play a role.
For a healthy adult weighing 75 kg:
- Baseline limit: 400 mg
- Weight-based calculation: 75 kg * 5 mg/kg = 375 mg
In this case, staying close to 375 mg daily would be a reasonable limit.
How much is 200 mg of caffeine?
To put 200 mg of caffeine into perspective:
- 2 cups (8 oz each) of brewed coffee
- 2.5 shots of espresso
- 5-6 cups of green or black tea
- 2 cans (16 oz each) of most energy drinks
- 5-6 cans (12 oz each) of cola
How much caffeine will be left in his bloodstream after 4 hours, after 8 hours, and after 12 hours?
Let’s say someone consumes 300 mg of caffeine at 8:00 AM.
- After 4 hours (12:00 PM): ~225 mg remaining
- After 8 hours (4:00 PM): ~150 mg remaining
- After 12 hours (8:00 PM): ~75 mg remaining
Caffeine has a half-life of approximately 5-6 hours in healthy adults.
Is 700mg of caffeine a lot?
Consuming 700 mg of caffeine in a day is considered very high and exceeds recommended limits for most adults.
- 7 cups of coffee
- 8-9 energy drinks
- 17-20 cans of cola
Such high intake can lead to:
- Increased anxiety and restlessness
- Rapid heart rate
- Insomnia
- Digestive issues
- Potential caffeine toxicity
How much caffeine in irn bru?
Irn Bru, a popular Scottish carbonated soft drink, contains approximately 32 mg of caffeine per 330 ml can.
- Coffee (8 oz): 95-200 mg
- Cola (12 oz): 30-40 mg
- Energy drinks (8.4 oz): 70-80 mg
For someone consuming Irn Bru as their primary caffeine source, they would need to drink about 12 cans to reach the 400 mg daily limit, which is unlikely for most individuals.
Sources
- National Center for Biotechnology Information: Caffeine
- FDA: Spilling the Beans: How Much Caffeine is Too Much?
- Mayo Clinic: Caffeine: How much is too much?
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