Monster Energy vs Reign: caffeine compared
Reign (16 oz) has 300 mg of caffeine, 140 mg more than Monster Energy (16 oz, 160 mg) — 1.9× as much per serving. Per fluid ounce, Reign is the stronger drink: 18.8 mg/oz versus 10.0 mg/oz.
| Monster Energy | Reign | |
|---|---|---|
| Serving | 16 oz | 16 oz |
| Caffeine per serving | 160 mg | 300 mg |
| Per fl oz | 10.0 mg | 18.8 mg |
| Share of 400 mg/day | 40% | 75% |
| Servings to reach 400 mg | 2.5 | 1.3 |
| Hours until under 50 mg | 8.4 h | 12.9 h |
| Last one for an 11 PM bedtime · standard (50 mg) | 2:37 PM | 10:05 AM |
| Last one for an 11 PM bedtime · sensitive (25 mg) | 9:37 AM | 5:05 AM |
| Share of the 200 mg pregnancy limit | 80% | 150% |
One serving of each, over 16 hours
Common questions
Which has more caffeine, Monster Energy or Reign?
Reign (16 oz) has about 300 mg versus 160 mg in Monster Energy (16 oz): 140 mg more, or 1.9× as much.
Which is stronger per ounce, Monster Energy or Reign?
Reign: about 18.8 mg per fl oz versus 10.0 mg for Monster Energy. Serving size decides the total you actually drink.
How many Monster Energy servings equal one Reign?
About 1.9 servings of Monster Energy (16 oz) match the caffeine in one Reign (16 oz).
When should I stop drinking Monster Energy or Reign before bed?
For an 11 PM bedtime with a 50 mg limit and a 5-hour half-life: last Monster Energy by 2:37 PM, last Reign by 10:05 AM. Half-life varies from about 1.5 to 9.5 hours between people.
Method
Caffeine per labeled serving, from the same drink table every calculator here uses (FDA/USDA reference amounts and manufacturer labels; see caffeine content of every drink). Brewed drinks vary batch to batch, so read these as typical values. Decay uses a 5-hour average half-life with a 45-minute absorption ramp; cutoff = bedtime − 5 h × log₂(dose ÷ limit). Percentages use the FDA's 400 mg/day figure for healthy adults and the 200 mg/day limit ACOG gives for pregnancy.
Source — Monster Energy: CSPI caffeine chart (Monster Energy Original, 16 oz), checked 2026-10-13.
Source — Reign: Monster Energy press release — REIGN Total Body Fuel (300 mg), checked 2026-10-13.