How much caffeine is in Diet Pepsi?
of caffeine
Source: public manufacturer data and USDA FoodData Central. Values are estimates, not exact or medical measurements.
- 35 mg of caffeine per 355 ml (12 fl oz) serving (9.9 mg per 100 ml).
- About 0.4 cups of brewed coffee, and 9% of the FDA's 400 mg daily limit for healthy adults.
- After 6 hours roughly 17 mg is still in your system; after 12 hours about 8 mg.
- To stay under the 100 mg many people notice at bedtime, finish it about 0 h before sleep.
Diet Pepsi delivers about 35 mg of caffeine per 355 ml (12 fl oz) serving, the equivalent of roughly 0.4 cups of brewed coffee (a 240 ml cup is about 96 mg). That is about 61 mg less caffeine than a standard cup of coffee.
At 9.9 mg per 100 ml, Diet Pepsi is low by concentration — the fair way to compare it against drinks of a different size.
How long Diet Pepsi stays in your system
Caffeine leaves the body through first-order elimination with a population-average half-life of about 5.7 hours. Starting from 35 mg, roughly 24 mg is left after 3 hours, about 17 mg after 6 hours, and around 8 mg after 12 hours. Your personal rate varies — smoking speeds it up, pregnancy and some medications slow it down — which is why the calculator below lets you set your own half-life and bedtime.
Diet Pepsi and your daily limit
For most healthy adults the FDA points to about 400 mg of caffeine a day as an amount not generally linked to negative effects. One serving of Diet Pepsi is 9% of that ceiling. Pregnant people are usually advised to stay under about 200 mg a day, and the American Academy of Pediatrics discourages caffeine for children and adolescents. This is general guidance, not medical advice. The easiest way to stay under your own limit is to log every drink — CoffeeLog adds up your real daily total automatically.
How long it stays in your system
Starting from one serving, here is roughly how much caffeine is left as the hours pass (population-average half-life of 5.7 hours).
| Time | Caffeine left | % left |
|---|---|---|
| At serving | 35 mg | 100% |
| After 1 h | 31 mg | 89% |
| After 3 h | 24 mg | 69% |
| After 6 h | 17 mg | 49% |
| After 9 h | 12 mg | 34% |
| After 12 h | 8 mg | 23% |
Your personal caffeine curve
Estimates for general information, not medical advice.
How it compares
| Drink | Serving | Caffeine |
|---|---|---|
| Diet Pepsi | 355 ml | 35 mg |
| Club-Mate | 330 ml | 66 mg |
| Mountain Dew | 355 ml | 54 mg |
| Coca-Cola Diet Coke | 355 ml | 46 mg |
| Dr Pepper | 355 ml | 42 mg |
| Sunkist Orange | 355 ml | 41 mg |
| Pepsi | 355 ml | 38 mg |
Frequently asked questions
How much caffeine is in Diet Pepsi?
Diet Pepsi contains about 35 mg of caffeine per 355 ml (12 fl oz) serving (9.9 mg per 100 ml). Values are public-source estimates, not exact measurements.
Is 35 mg of caffeine a lot?
It is about 0.4 cups of brewed coffee. The FDA considers up to 400 mg per day safe for most healthy adults, so this is a moderate single dose.
How long does the caffeine in Diet Pepsi stay in your system?
Caffeine has a half-life of about 5.7 hours, so roughly 24 mg of the original 35 mg remains after 3 hours and about 8 mg after 12 hours. The calculator above shows your personal curve.
Will Diet Pepsi keep you awake?
It can if you have it late. From 35 mg it takes roughly 0 hours to fall below the 100 mg level many people notice at bedtime. Finish it well before sleep, or use the cutoff above.
Track this automatically with CoffeeLog
Log any drink in one tap, watch caffeine fade in real time on your home screen, and get a nudge before it touches your sleep — the same engine that powers this page.
Related
TrackCaffeine provides general reference information about caffeine. It is not medical advice. Caffeine values are public-source estimates, not exact measurements.