How rare it really is
Under 1% of people are ambidextrous in the strict sense: equally skilled with either hand at everything, writing included. Widen the definition to anyone who simply isn't cleanly right-handed and you reach 18.1%. Both figures are correct.
That gap is not sloppy measurement. It is the heart of the whole business, and almost nobody repeating "about 1%" bothers to explain it.
The number nobody explains
The best source we have is a 2020 meta-analysis in Psychological Bulletin, built specifically to settle the question[1]. Its result is not a number. It is a range.
- 9.3% left-handed under the strictest criterion
- 18.1% non-right-handed under the most lenient one
- 10.6% as the best estimate — 10.4% once elite-athlete studies come out
Now look at what sits in between. Nearly nine points of the population fall between one definition and the other: the mixed-handed, who get filed as left, right or ambidextrous depending purely on which questionnaire you hand them.
So "1% of people are ambidextrous" means nothing more than this: somebody picked the narrowest threshold.
Three different things, one word
- True ambidexterity — the same skill at every task, writing included. Well under 1%.
- Mixed-handedness — different hands for different jobs. Write right, throw left. Extremely common.
- Trained ambidexterity — a second hand deliberately brought up to standard. No prevalence study measures it: they all ask what you do, never what you could do.
A million hands
Two studies dwarf all the others, and both deserve to be known by name.
In 1992 Gilbert and Wysocki analysed 1,177,507 Americans aged 10 to 86, gathered through a National Geographic survey[2]. Over a million responses. Nobody has beaten it since.
The second is the BBC internet study: 255,100 people, one question about your writing hand[3]. Its left-handedness rate came out almost identical to Gilbert and Wysocki's — two wildly different methods landing in the same place. That is the most reassuring thing you can ask of a statistic.
The caveat is heavy, though. Both are self-report on very few tasks. Neither tested whether a single person could have become two-handed.
A quarter inherited
This is the number that changed how I think about all of it.
A twin and singleton study puts the heritability of handedness between 20% and 27%, depending on the measure used[4]. Barely a quarter.
Which leaves roughly three quarters to everything else: development, environment, habit, practice.
The same study dismantles a belief you have certainly met. Twins are said to be far more often left-handed than everyone else. In that sample they simply were not: 8.1% against 7.8%, a difference that never reached significance.
Two more to carry away. Men are left-handed by about 2.09 percentage points more than women[1]. And hand preference correlates with hand performance at only about 0.4[4] — which hand you prefer and which one you are actually good with are not the same measurement.
The athlete myth
Here I expected the data to confirm the obvious. It didn't.
A meta-analysis of 164 studies and 145,135 people looked at feet[5]. Experienced athletes are markedly more often left-footed: 20.0% against 11.4% in the general population. But on mixed-footedness — the closest thing to real two-sidedness — there is no significant difference between athletes and everyone else.
Football confirms it. Across 236 players from 16 squads at the 1998 World Cup, the professionals were as right-footed as everybody else, around 79%, and very few used both feet with equal frequency[6].
And yet the second foot pays. Across the salaries of Europe's five big leagues there is a substantial premium for players who use both well, even controlling for performance[7]. Scarcity is exactly what makes it valuable.
Baseball gives the cleanest numbers of all, because switch-hitting is a status written on the roster. Among qualified hitters: 4% in 1951, nearly 25% by the end of the 1980s, 9% in 2008, a peak of 18% in 2018, 12.5% in 2022[8].
Stop on that swing for a second. Between 1951 and 1989 human genetics did not move a millimetre. The coaching changed. When that sport decided to produce two-sided hitters, it produced them.
What nobody measured
Every figure above describes what people do. Not one describes what they could do.
Prevalence studies hand you a questionnaire and record your habits. They do not take a thousand adults, train the weak hand for a year and measure the result. That study simply does not exist.
So the honest position is this: we know how many people are ambidextrous by accident, and we do not know how many could become so.
Want to know where you sit? The ambidextrous test takes two minutes. If it's the trainability argument you're after, I've made it properly in can you become ambidextrous, and the feet have statistics all their own over in ambidextrous feet.
Which of these numbers surprised you most? Tell me in the comments — and if it was useful, send it to whoever keeps repeating that 1% line at you.
Cite these freely
If you are a journalist, a student or another blogger: use them. I only ask that you cite the original study rather than this page. The full list is at the bottom.
- True ambidexterity under 1%; left-handed 9.3%, non-right-handed 18.1%, best estimate 10.6% — Papadatou-Pastou et al., 2020[1]
- 1,177,507 respondents in the largest handedness survey ever run — Gilbert & Wysocki, 1992[2]
- Heritability of handedness 20–27% — Zheng et al., 2020[4]
- Athletes 20.0% left-footed against 11.4%, but no difference in mixed-footedness — Packheiser et al., 2020[5]
- MLB switch-hitters among qualified batters: 4% (1951), 25% (late 1980s), 12.5% (2022)[8]
One request, sincerely meant: if you quote the 1%, quote the definition beside it. The number alone means nothing, and the internet is already full of the number alone.
From statistic to gesture
Statistics describe a population. They do not describe you.
A quarter inherited means three quarters is something else. And that something else is the part you get a say in. I started training my left hand expecting a very low ceiling, and found the ceiling was made almost entirely of never having tried.
In my book "How to Become Ambidextrous" you'll find the structured version of all this: a proper self-assessment, graded exercises for writing, drawing and coordination, and a day-by-day programme for taking your other hand from useless to genuinely useful.
It's the book I went looking for when I started. I couldn't find it, so I wrote it.
Get it on Amazon and stop being a statistic about other people!