Articles

Stories and guides about hard-to-picture quantities: areas, volumes of water, weights… always with the figure drawn to scale so it actually sinks in.

Hectares

Hectare, acre and fanega: why land was measured in days of work

A hectare is 10,000 m², an acre 4,046.86 m², and a Spanish fanega depends on the province. Every area unit in one table, and why almost all of them measure a day of work, except the hectare.

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Money

How much is a billion? And why a Spanish billón is a trillion

A billion is a thousand million (9 zeros); the Spanish billón is a million million (12 zeros), our trillion. The two scales in one table, where the mess comes from (Chuquet, 1484) and how to translate without slipping a factor of a thousand.

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Distances

Where does the foot come from?

A foot is exactly 0.3048 metres, but no human foot is: an adult of 5 ft 9 in has a 26.8 cm foot. From the sixteen men outside the church to the three barleycorns of Edward II and the 1959 treaty that defined the foot in metres.

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Distances

The origin of the metre

The metre was defined in 1791 as one ten-millionth of the meridian quadrant. Delambre and Méchain spent seven years measuring the arc from Dunkirk to Barcelona, got it slightly wrong, and the metre is still 0.2 mm shorter than it should be.

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Distances

What is a mile?

A mile is 5,280 feet: 1,760 yards, eight furlongs and exactly 1,609.344 metres. From the thousand paces of a Roman legionary to the 1593 statute that stretched it to avoid a tax rise. With a conversion table and drawn to scale on the map.

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Distances

From the foot to the metre: why we measure distance the way we do

A kilometre is a thousand metres and a mile is 1,609.344: one of those numbers was chosen and the other was not. The table of every distance unit, the 0.2 mm error still inside the metre, and why a mile is 5,280 feet.

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Distances

How far away is the horizon?

From the beach the horizon is only 2.9 miles (4.7 km) away. The formula (1.22 × the square root of your height), a table by height, why mountains show up 60 miles out, and your horizon drawn to scale on a map.

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Liters

How many litres of water are in a bathtub?

A standard 170 × 70 cm bathtub is rated at 183 litres (48 gallons) and a real bath uses about 150. Capacities by size, how many minutes of shower equal a bath, and how to measure your own.

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Distances

How long is a marathon?

A marathon is 26.2 miles — 26 miles 385 yards, or 42.195 km — and a half marathon 13.11 miles. Why that odd figure, pace and finishing times, drawn to scale on a map.

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Distances

How long is a nautical mile?

A nautical mile is exactly 1,852 metres (1.852 km, 1.15 statute miles) — 15 % longer than a land mile. Why it measures that, what a knot is and a conversion table, drawn on a map.

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Distances

How far is 10,000 steps?

10,000 steps come to about 7.5 km (4.7 miles) — between 7 and 8 km. Where the figure comes from, how many steps you really need and how long it takes. See it drawn to scale on a map.

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Liters

How many litres of water are in an Olympic swimming pool?

An Olympic swimming pool holds about 2.5 million litres (2,500 m³): some 16,667 bathtubs or 83 tanker trucks. Official size, equivalents and what it costs to fill.

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How much is…?

HectaresHow big are 1,000 hectares? See it on a map DistancesHow far is 10 km? LitersHow much is a million litres? KilosHow heavy is 40,000 kg? MoneyHow much is a million dollars? Measure an areaDraw on the map and get the hectares Measure a distanceTrace a route point by point Area converterHectares to m², acres and km² Distance converterKilometres to miles, feet and yards