US · Energy drinks
How much caffeine is in REIGN Total Body Fuel?
A US 16 fl oz REIGN can lists 300 mg. Formulations in other countries can be lower, so check the local label.
Interactive serving
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Source and provenance
- Source type
- Manufacturer
- Market
- US
- Value basis
- Manufacturer listed
- Source reviewed
- 21 August 2026
US product page; formulations in other markets can differ.
Estimated caffeine remaining over time
These figures apply CaffCalc’s exponential model to the adjusted 300 mg starting value. They are calculations, not measurements of caffeine in a particular person.
| Hours elapsed | 3-hour half-life | 5-hour half-life | 7-hour half-life |
|---|---|---|---|
| 0 | 300 mg | 300 mg | 300 mg |
| 3 | 150 mg | 197.9 mg | 222.9 mg |
| 5 | 94.5 mg | 150 mg | 182.9 mg |
| 8 | 47.2 mg | 99.0 mg | 135.9 mg |
| 10 | 29.8 mg | 75 mg | 111.4 mg |
| 12 | 18.8 mg | 56.8 mg | 91.4 mg |
With the central five-hour model, the estimate falls below 25 mg after approximately 17.9 hours. The faster and slower columns show why one fixed clearance time should not be treated as a personal fact.
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Same category, lower documented dose
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These suggestions use documented servings in the same category and compare caffeine quantity only. Check the evidence badge before relying on a reported figure.