How much caffeine is in a Monster? A 16 oz can of original green Monster Energy has 160 mg, Monster Zero Sugar also has 160 mg, Zero Ultra has 150 mg, Rehab has 160 mg per 15.5 oz and Java Monster has 200 mg per 15 oz, according to Monster's own product pages. That makes a standard Monster roughly the same as one and a half to two cups of brewed coffee.
At an average 5-hour half-life, a 160 mg can takes a little over 13 hours to fall below 25 mg. So for an 11 PM bedtime, a Monster is really a breakfast drink. The caffeine calculator works out your own cutoff for any can and bedtime.
Free toolCaffeine Cutoff CalculatorHow much caffeine is still in you at bedtime, and your latest cup.How much caffeine is in each Monster drink?
Most 16 oz Monster cans carry 150 to 160 mg, and Java Monster is the strongest of the main lines at 200 mg. These figures come from monsterenergy.com product pages, checked in October 2026. Monster states each number for a specific can size, shown below.
| Drink | Size Monster bases it on | Caffeine |
|---|---|---|
| Monster Energy (original green) | 16 fl oz | 160 mg |
| Monster Energy Zero Sugar | 16 fl oz | 160 mg |
| Monster Zero Ultra (white can) | 16 fl oz | 150 mg |
| Rehab Monster (Tea + Lemonade, Peach Tea, Green Tea, Wild Berry) | 15.5 fl oz | 160 mg |
| Java Monster (Mean Bean, Loca Moca, Salted Caramel) | 15 fl oz | 200 mg |
| For comparison: brewed coffee | 8 fl oz | about 95 mg |
Monster sells many of these in other sizes too, such as 12, 19.2 and 24 oz cans. Its pages give caffeine only for the size in the table, so for a bigger can, check the label rather than guessing. Recipes change and amounts can differ outside the US.
How much caffeine is in Monster Zero Sugar?
Monster Zero Sugar has 160 mg of caffeine per 16 oz, the same as the original green can. Monster describes it as the original taste without the sugar. Removing sugar doesn't remove caffeine, so for sleep it counts exactly like a regular Monster.
How much caffeine is in a Zero Ultra Monster?
Monster Zero Ultra has 150 mg of caffeine per 16 oz. Most of the Ultra flavors we checked on Monster's site list the same 150 mg, but a few differ, such as Ultra Red at 140 mg and Ultra Red, White and Blue Razz at 160 mg. If you have a favorite flavor, its own page or can is the number to trust.
How much caffeine is in Rehab Monster?
Rehab Monster has 160 mg of caffeine per 15.5 oz can, across the Tea + Lemonade, Peach Tea, Green Tea and Wild Berry flavors we checked. It's non-carbonated and tastes more like iced tea, which makes it easy to drink fast and forget it's a full energy drink. It carries as much caffeine as an original Monster.
How much caffeine is in Java Monster?
Java Monster has 200 mg of caffeine per 15 oz can in Mean Bean, Loca Moca and Salted Caramel. That's the most of any line here, about two cups of brewed coffee. Because it's a coffee drink, people often stack it on top of their morning coffee, which pushes the day's total up quickly.
How much Monster caffeine is left at bedtime?
A 160 mg Monster at 2 PM still leaves about 46 mg in you at 11 PM. The table uses the calculator's math: remaining caffeine = dose x 0.5^(hours / 5), for an 11 PM bedtime.
| Can at | Zero Ultra (150 mg) | Original, Zero Sugar or Rehab (160 mg) | Java Monster (200 mg) |
|---|---|---|---|
| 8 AM | 19 mg | 20 mg | 25 mg |
| 10 AM | 25 mg | 26 mg | 33 mg |
| Noon | 33 mg | 35 mg | 44 mg |
| 2 PM | 43 mg | 46 mg | 57 mg |
| 4 PM | 57 mg | 61 mg | 76 mg |
| 6 PM | 75 mg | 80 mg | 100 mg |
This site uses about 25 mg at bedtime as a sensible ceiling. It isn't an official limit, just a useful line. A Monster at 6 PM leaves about as much caffeine at bedtime as a small cup of coffee, and a Java Monster at 6 PM leaves about a full one.
What's the latest time to drink a Monster?
For an 11 PM bedtime, finish a 16 oz Monster or Zero Sugar by about 9:37 AM, a Zero Ultra by about 10:05 AM and a Java Monster by about 8:00 AM. These are the times each can falls below 25 mg by bed:
| Bedtime | Zero Ultra (150 mg) | Original, Zero Sugar or Rehab (160 mg) | Java Monster (200 mg) |
|---|---|---|---|
| 10:00 PM | 9:05 AM | 8:37 AM | 7:00 AM |
| 10:30 PM | 9:35 AM | 9:07 AM | 7:30 AM |
| 11:00 PM | 10:05 AM | 9:37 AM | 8:00 AM |
| Midnight | 11:05 AM | 10:37 AM | 9:00 AM |
In hours before bed, that's about 12 h 55 min for Zero Ultra, 13 h 23 min for a 160 mg can and 15 hours for Java Monster. These are averages. If caffeine tends to linger for you, the caffeine calculator has a high-sensitivity setting that moves the cutoff earlier.
An afternoon can doesn't have to keep you awake to cost you sleep. In an at-home study, a large caffeine dose taken 6 hours before bed cut total sleep by more than an hour. For how energy drinks fit into the bigger sleep picture, see energy drinks and sleep. If you're comparing brands, Red Bull's caffeine by can size is lower per can.
How many Monsters a day is safe?
For healthy adults, the FDA cites 400 mg of caffeine a day as an amount not generally linked to negative effects. That's two 160 mg Monsters plus a little coffee, or two Java Monsters on their own. A third can puts most people over.
That figure is for adults only. The FDA notes that medical experts advise against energy drinks for children and teens because of their sugar and caffeine, and that too much caffeine in young people can cause a racing heart, anxiety and sleep problems. If you're pregnant, breastfeeding, have a heart condition or take medications, talk to your health care provider about a lower limit. To tally a full day, see how much caffeine is too much.