Caffeine in drinks
How much caffeine is in Kit Kat?
Sources checked claim by claim by an AI review. Approved for publishing by Oleksii Y. on 2026-10-19.
One 1.5 oz bar (42 g) of Kit Kat has 5.9 mg of caffeine, according to USDA Agricultural Research Service, FoodData Central (SR Legacy).
How Kit Kat compares
- Strength: 14 mg per 100 g.
- One 1.5 oz bar (42 g) has as much caffeine as less than a sixth of a cup of brewed coffee, which has 94.8 mg per 8 fl oz cup.
- Of the 9 other candy bars and chocolate candies in our candy bars chart, 2 have more caffeine per serving and 7 have less.
How much will be left at bedtime?
1 × 1.5 oz bar (42 g) of Kit Kat
Left at 11:00 PM (8 h later), average metabolism
≈ 1.9 mg
Range 0.9–3 mg (fast to slow metabolism)
5.9 mg is already at or under the 50 mg this tool aims to have left at bedtime.
Estimate from a simple model: half-life of 3, 5 or 8 hours, 50 mg bedtime target. How we calculate
Caffeine by size
| Serving | Caffeine |
|---|---|
| 1.5 oz bar (42 g) | 5.9 mg |
| 1.625 oz bar (46 g) | 6.4 mg |
| Miniature bar (10 g) | 1.4 mg |
How long does Kit Kat stay in your system?
Our model halves caffeine every 5 hours for average metabolism, and every 3 or 8 hours for fast or slow metabolism. From one 1.5 oz bar (42 g) of Kit Kat (5.9 mg), about 3 mg is still in your body 5 hours later and about 1.5 mg after 10 hours. If you clear caffeine slowly (an 8-hour half-life), about 2.5 mg is left after 10 hours.
Estimated caffeine left at 11:00 PM from one 1.5 oz bar (42 g) (5.9 mg), using a half-life of 5 hours for average metabolism and 3 to 8 hours for the range. How we calculate
| Had at | Left at bedtime (average) | Range |
|---|---|---|
| 8:00 AM (15 h before bed) | ≈ 0.7 mg | 0.2–1.6 mg |
| 12:00 PM (11 h before bed) | ≈ 1.3 mg | 0.5–2.3 mg |
| 3:00 PM (8 h before bed) | ≈ 1.9 mg | 0.9–3 mg |
| 6:00 PM (5 h before bed) | ≈ 3 mg | 1.9–3.8 mg |
How many fit in a day?
Reference amounts are for caffeine from all sources combined. Counted at the upper end of the stated amount, one serving at a time:
- Up to 400 mg a day for most healthy adults (FDA, EFSA): about 67 servings.
- Up to 200 mg at one time for healthy adults (EFSA): about 33 servings in one go.
- Up to 200 mg a day in pregnancy (EFSA, NHS): about 33 servings.
These are reference amounts for groups of people, not a personal limit. Some people feel jittery or sleep worse on much less. See the cutoff calculator for timing.
Good to know
USDA also has a separate KIT KAT BIG KAT record that shows 0 mg of caffeine, a value supplied by the manufacturer; the wafer bar figure used here comes from a lab sample.
How the serving amount was worked out: USDA lists 14 mg per 100 g, from 1 lab sample; 42 g × 0.14 = 5.88 mg, rounded to 5.9 mg; 46 g × 0.14 = 6.44 mg, rounded to 6.4 mg; 10 g × 0.14 = 1.4 mg.
Common questions
How much caffeine is in Kit Kat?
USDA Agricultural Research Service, FoodData Central (SR Legacy) gives 5.9 mg of caffeine per 1.5 oz bar (42 g). Other sizes are in the table on this page.
How many Kit Kat servings can I have in a day?
The FDA and EFSA cite up to 400 mg of caffeine a day, from all sources combined, for most healthy adults. At 5.9 mg per 1.5 oz bar (42 g), that is about 67 servings if Kit Kat is your only source. In pregnancy the reference is 200 mg a day.
How late can I drink Kit Kat?
One serving has about 5.9 mg, which is at or under the 50 mg our calculator aims to have left at bedtime, so it sets no cutoff for a single serving. Several servings add up.
How long does Kit Kat stay in your system?
Of the 5.9 mg in one 1.5 oz bar (42 g), roughly 3 mg remains after 5 hours and 1.5 mg after 10 hours with our average 5-hour half-life. From fast to slow metabolism, 10 hours later it is between 0.6 and 2.5 mg.
Where the number comes from
- Candies, KIT KAT Wafer Bar. USDA Agricultural Research Service, FoodData Central (SR Legacy). FDC ID 167992, nutrient "Caffeine" (262): 14 mg per 100 g, derivation A (analytical), 1 data point; portions "bar (1.5 oz)" = 42 g, "bar (1.625 oz)" = 46 g, "bar, miniature (.35 oz)" = 10 g. Hershey's site, which sells Kit Kat in the US (hersheyland.com returned HTTP 406 to its product and FAQ pages), gave no caffeine figure we could read on 2026-10-13, so these numbers are USDA's. Accessed 2026-10-09. Source ↗
- Candies, HERSHEY, KIT KAT BIG KAT Bar. USDA Agricultural Research Service, FoodData Central (SR Legacy). FDC ID 169629, nutrient "Caffeine" (262): 0 mg per 100 g, derivation MC (manufacturer supplied). Accessed 2026-10-09. Source ↗
Recipes and labels change. If a number here no longer matches the label, the label wins.
General information, not medical advice
If you feel unwell after caffeine — for example chest pain, a fast or irregular heartbeat that does not settle, fainting, confusion or trouble breathing — get urgent medical help. If you are pregnant or breastfeeding, under 18, take medication, or have a heart, liver or anxiety condition, high blood pressure or a sleep disorder, ask a doctor or pharmacist what amount is right for you.
Sources
- U.S. Food and Drug Administration (2024). Spilling the Beans: How Much Caffeine is Too Much? FDA Consumer Updates. fda.gov ↗
- European Food Safety Authority. Caffeine | EFSA. EFSA topic page (summary of the 2015 Scientific Opinion on the safety of caffeine). efsa.europa.eu ↗
- NHS. Foods to avoid in pregnancy. NHS. nhs.uk ↗
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