How much caffeine is in Kit Kat?

One bar (1.5 oz, 42 g) of Kit Kat has 5.9 mg of caffeine.

You would need about 16 of these to equal a cup of brewed coffee (95 mg).

Source: USDA FoodData Central · checked 10 Nov 2026

When did you have it?

Had at 3 pm, about 2.1 mg is still in you at an 11 pm bedtime. That should not affect most people’s sleep.

Bedtime

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Per 100 g that is about 14 mg of caffeine.

Latest time to eat it

For an 11 pm bedtime, one bar (1.5 oz, 42 g) of Kit Kat stays under the 50 mg most people sleep fine with, even late in the evening. The table works it out for other bedtimes and for how sensitive you are: it is the latest time to start one so that the caffeine left stays under the line all night.

Bedtime	Very sensitive under 25 mg	Average under 50 mg	Not very sensitive under 100 mg
9 pm	Any time	Any time	Any time
10 pm	Any time	Any time	Any time
11 pm	Any time	Any time	Any time
Midnight	Any time	Any time	Any time
1 am	Any time	Any time	Any time

For one bar (1.5 oz, 42 g) of Kit Kat, average clearance (half-life 5 h), 8 hours of sleep. "Any time" means even one at bedtime stays under the line.

How long it lasts

The caffeine from one bar (1.5 oz, 42 g) of Kit Kat peaks in your blood about 75 minutes after you start it, at roughly 5 mg. Half of it is gone in about 5 hours for an average adult; that ranges from roughly 3 to 7 hours, and longer in pregnancy or with some medicines.

Time after	3 hours	6 hours	9 hours	12 hours
Still in you	4.1 mg	2.7 mg	1.8 mg	1.2 mg

So one had at 3 pm leaves about 2.1 mg at 11 pm. How long caffeine lasts explains the curve.

How it compares

Kit Kat is stronger than 8% of the 37 foods we track, by caffeine per serving.

To reach 400 mg in a day you would need about 68 of these.

Less caffeine

M&M's Peanut 5.4 mg, 1 bag
Chocolate Pudding 5.2 mg, 1 cup
Twix Chocolate Fudge 5.1 mg, 2 bars

More caffeine

Chocolate Gelato 7 mg, 1 cup
Hot Chocolate 7.4 mg, 8 fl oz cup
Chocolate Frozen Yogurt 8.8 mg, 1 cup

FAQ

Is Kit Kat high in caffeine?

No, it is low. One bar (1.5 oz, 42 g) of Kit Kat has 5.9 mg, which is 6% of the 95 mg in an 8 fl oz cup of brewed coffee.

Can I eat Kit Kat at night?

For most people, yes: even late in the evening one bar (1.5 oz, 42 g) of Kit Kat stays under 50 mg at an 11 pm bedtime.

How long does the caffeine in Kit Kat last?

It peaks about 75 minutes after you start it. Of the 5.9 mg, about 2.7 mg is still in you 6 hours later and 1.2 mg after 12 hours, for an average adult with a 5-hour half-life.

Does Kit Kat have more caffeine than a cup of coffee?

No. One bar (1.5 oz, 42 g) of Kit Kat has 5.9 mg; an 8 fl oz cup of coffee has 95 mg.

Method and limits

The caffeine figure comes from USDA FoodData Central; recipes, brewing and batches vary, so a real serving can differ. The curves use a standard one-compartment model with an average 5-hour half-life and a sleep-friendly line of 50 mg; your own body may clear caffeine faster or slower. How it works has the details.

These are estimates for information, not medical advice.