Flip a Coin: Heads or Tails

Written byOleh Soloninupdated 5 October 2026

How many flips

One flip settles an argument; a run shows what randomness looks like.

Advanced options

Seed (optional)

Type a word and the flip becomes reproducible: the same word always gives the same result. Leave it empty for a fair random flip.

Result

ResultPress "Flip the coin"

One tap, one fair flip

Flip a coin online with one tap and get a fair heads or tails. Flip up to 1,000 times in a row to see the count of heads and tails and the longest streak.

A coin settles an argument without anyone having to back down: two outcomes, even odds, nothing left to discuss. Press Flip the coin and you get heads or tails.

Each flip comes from the browser's cryptographic random number generator, so it cannot be predicted in advance. If the result needs to be checkable, type a seed: the same word always gives the same flip.

How to use

Press Flip the coin and heads or tails appears below the button. Flip again to throw once more.
To flip a series, enter the number of flips, up to 1,000, and the tool counts heads, tails and the longest streak.
For a draw someone else can verify, open the extra fields and type a seed, such as the name of the match.

Settling a decision with a coin

Agree who takes which side before the flip; afterwards is too late. Agree too whether it is one flip or best of three, so nobody asks for a rethrow once they have lost.

If you are not in the same room, agree on a seed such as "friday dinner". Each of you opens the page and sees the same result. With more than two options a coin will not do: use the random decision generator for a list, or the dice roller for numbers.

How long streaks get with a fair coin

A streak is the same side several times in a row, and fair coins produce long ones far more often than people expect. In ten flips, a run of three or more of the same side turns up 83% of the time, so five heads in a row is no sign that anything is wrong with the coin.

Probability that the longest run of heads or tails is at least this long. Worked out by exact enumeration of every sequence.
Longest streak at least	10 flips	20 flips	100 flips
3	82.6%	97.9%	≈ 100%
4	46.5%	76.8%	99.97%
5	21.7%	45.8%	97.2%
6	9.4%	23.7%	80.7%
7	3.9%	11.5%	54.2%
8	1.6%	5.4%	31.5%
10	0.2%	1.2%	8.7%

Why you rarely get exactly half heads

The more you flip, the closer the share of heads gets to one half, yet an exact split becomes rarer. Exactly 5 heads in 10 flips happens 24.6% of the time, exactly 50 in 100 flips 8%, and exactly 500 in 1,000 only 2.5%. Meanwhile 40 to 60 heads out of 100 comes up in 96.5% of series.

Exact binomial probability for a fair coin.
Flips	Exactly half heads	Heads between 40% and 60%
10	24.6%	65.6%
20	17.6%	73.7%
100	8.0%	96.5%
1,000	2.5%	≈ 100%

What this calculator shows

Heads or tails at the press of a button
The whole sequence when you flip more than once
The count of heads and tails, the share of heads and the longest streak

What to keep in mind

The coin is fair: exactly even odds and no landing on the edge.
Without a seed a flip is random and cannot be repeated. With a seed it is reproducible: the same word and number of flips give the same sequence.

FAQs

Is the flip fair?

Yes. Without a seed every flip comes from the browser's cryptographic random number generator, so heads and tails each have a 50% chance and earlier flips have no effect on the next one. With a seed the series is fixed and repeats.

After five heads, is tails more likely?

No. The coin keeps no record of earlier flips, so the sixth is still exactly even. Expecting things to even out is called the gambler's fallacy.

How do I flip a coin several times?

Enter the number of flips, up to 1,000 at once. You get the full sequence, the count of heads and tails, and the longest streak.

What is the seed for?

It makes a flip repeatable. A draw nobody can check proves nothing; with a seed, the other person types the same word and sees the same result.

How long a streak is normal?

In ten flips a streak of three or more happens 83% of the time, and in a hundred flips a streak of six or more 81% of the time. Long streaks are an ordinary part of randomness.

Why don't 100 flips give exactly 50 heads?

Exactly 50 comes up in only 8% of hundred-flip series, while 40 to 60 heads comes up in 96.5%. The share heads towards one half, but an exact tie is rare.

Worked example

Ten flips from a seed

Input: seed "example", 10 flips

Output: 6 heads, 4 tails, longest streak 3

Note: Heads came up three times in a row, flips four to six. A streak of three or more in ten flips happens 82.6% of the time, so this is exactly what chance looks like.

Useful links

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Flip a Coin: Heads or Tails

Result

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