Statistics · Data · Probability

Statistics Calculators

Eight tools for real data work — standard deviation, mean/median/mode, probability, z-scores, fractions, permutations and combinations, sample size and percent error — plus a tour of the most fascinating statistics of the modern world.

Standard Deviation Calculator

Enter numbers separated by commas or spaces.

Enter at least two numbers.
Mean
Sample SD
Population SD
Variance (sample)
Count

Mean, Median & Mode Calculator

Enter numbers separated by commas or spaces.

Enter at least one number.
Mean
Median
Mode
Range

Probability Calculator

Probability of an event from favorable and total outcomes.

Favorable outcomes can't exceed total outcomes.
Probability
Decimal
Odds for

Z-Score Calculator

How many standard deviations a value sits from the mean, plus its percentile.

Z-score
Percentile

Fraction Calculator

Add, subtract, multiply or divide two fractions.

Denominators can't be zero (and you can't divide by a zero fraction).
Result
Decimal

Permutation & Combination Calculator

Ordered arrangements (nPr) and unordered selections (nCr).

r can't be larger than n.
Permutations (nPr)
Combinations (nCr)

Sample Size Calculator

How many people to survey for a given confidence and margin of error.

%
Recommended sample
Assumes maximum variability (p = 50%), the standard conservative choice for surveys.

Percent Error Calculator

Compare a measured value to the true (theoretical) value.

The theoretical value can't be zero.
Percent error
Absolute error
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Fascinating world statistics

Statistics aren't just formulas — they're the story of how our world is changing, told in numbers. Here are some of the most striking data trends of the modern era. (Figures are drawn from sources such as the UN, IMF, World Bank, ITU and UBS, and reflect the most recent estimates available; large round numbers are used for readability.)

The rise of the internet since its launch

The first public website went live in 1991. What happened next is one of the fastest adoption curves in human history: from a few million users to most of humanity in a single generation.

YearInternet usersShare of world
1995~39 millionunder 1%
2000~396 million~6%
2005~1 billion~16%
2010~2 billion~30%
2015~3 billion~40%
2020~4.7 billion~60%
2025~6 billion~74%

Today around 96% of users get online through a smartphone, and China and India alone account for over 2 billion of them. Yet more than 2 billion people — mostly in low-income countries — are still offline, one of the defining inequalities of the digital age.

Millionaires and billionaires over the years

Global wealth has exploded, and it has concentrated. The number of millionaires and billionaires has grown dramatically over recent decades.

MetricThenNow (2025–26)
Billionaires (count)~140 in 1987over 3,400 by 2026 — combined wealth ~$16 trillion
"Everyday" millionaires ($1–5M)~12 million in 2000~52 million
Total US-dollar millionaires~60 million, holding close to half of all global wealth (~$226 trillion)
Centibillionaires ($100B+)none until recentlyaround 15–20 individuals

The United States is home to roughly 40% of the world's millionaires — about 24 million people — and added over 1,000 new millionaires a day in recent years, driven largely by strong financial markets. Wealth is also increasingly inherited: a "great wealth transfer" is set to pass trillions of dollars to the next generation over the coming decades.

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The world's population over 50 years

One of the most consequential statistics of all: humanity doubled in just 50 years. From about 4 billion people in 1975, the world reached roughly 8.2 billion in 2025.

The global economy over 50 years

The world economy has grown even faster than its population. Global output now stands at roughly $115–117 trillion a year, and average income per person has climbed enormously — world GDP per capita is about $14,500, having risen many times over since the 1960s.

Economy and GDP per capita by continent

The averages hide vast gaps. A handful of wealthy regions produce most of the world's output, while the most populous continents earn far less per person.

ContinentPopulationGDP (nominal)GDP per capita
Asia~4.7 billion~$43 trillion~$9,600
Europe~745 million~$28 trillion~$38,300
North America~600 million~$32 trillion~$55,000+
Africa~1.5 billion~$3 trillion~$2,000

The contrast is stark: North America and Europe together produce more than half of global GDP with only about 15% of the world's people, while Africa — home to around 1.5 billion — contributes roughly 2–3%, an output similar to a single large European economy. Africa's GDP per capita has only risen from about $1,000 to $2,000 over the past 45 years, showing how uneven global growth has been.

What the world spends on

How humanity allocates its money is revealing. Healthcare is the single largest category of global spending, running into the tens of trillions of dollars a year worldwide. Global military spending has climbed past $2.4 trillion a year — the highest on record — while education, food, energy and technology each command trillions more. As economies have grown richer, spending has steadily shifted from basic necessities toward services, technology, healthcare and leisure — a pattern that repeats as each region develops. (Spending figures here are broad, recent approximations and shift year to year.)

Why these numbers matter: every figure above is a statistic — a mean, a total, a rate of change — and the same tools in our calculators above (averages, growth rates, sampling, probability) are exactly what analysts use to measure, compare and forecast them.

Frequently asked questions

How do I calculate standard deviation?

Find the mean, subtract it from each value and square the result, average those squares (÷ n for a population, ÷ n−1 for a sample), then take the square root. The Std Dev tab shows both versions and the variance.

How do I calculate permutations and combinations?

Permutations (order matters): nPr = n!/(n−r)!. Combinations (order doesn't): nCr = n!/(r!(n−r)!). Choosing 3 from 10 gives 720 permutations but 120 combinations.

How many internet users are there in the world?

About 6 billion in 2025 — roughly 74% of humanity — up from 396 million in 2000. Around 96% get online via smartphones, while over 2 billion remain offline.

How many millionaires and billionaires are there?

Roughly 60 million dollar-millionaires (holding nearly half of global wealth), and over 3,400 billionaires by 2026 with combined wealth around $16 trillion. The US holds about 40% of millionaires.

How much has the population grown in 50 years?

It doubled — from about 4 billion in 1975 to roughly 8.2 billion in 2025 — adding around 80 million people a year, with growth expected to level off near 10 billion later this century.

What is a z-score?

How many standard deviations a value is from the mean: z = (x − μ)/σ. Zero is average, +2 is well above, −1 is below. The Z-Score tab also gives the percentile.

Calculators are for education and reference. World statistics are approximate, drawn from public sources (UN, IMF, World Bank, ITU, UBS and others), and change over time — check the latest official figures for precise, current data.

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