Scale: how big things actually are
Almost everyone carries a distorted map in their head, because almost everyone learned from a Mercator projection that stretches the poles and flatters the north. Scale questions are the ones that catch people out most reliably, and they stay caught out even after being told.
Roughly how many drink cans would it take to fill the volume of Hawaii above sea level?
About 80 quadrillion
Hawaii's land area is about 28,300 km2 and its average height above sea level is roughly 1 km, giving very roughly 28,300 km3. A 330 ml can is 3.3e-13 km3. 28,300 / 3.3e-13 is about 8.6e16, so tens of quadrillions.
Source: Land area from the US Census; can volume is the standard 330 ml
How many countries the size of the United States would fit inside Africa?
About three
Africa is about 30.4 million km2 and the United States about 9.8 million km2. 30.4 / 9.8 is about 3.1. That is why Mercator maps, where they look similar, mislead so badly.
Source: Continental and national areas, CIA World Factbook
Is the Pacific Ocean larger than all of the Earth's land put together?
Yes, by about 20 million km2
The Pacific covers about 165 million km2 and all land about 149 million km2, so the Pacific alone beats every continent combined, by roughly 16 to 20 million km2 depending on where its southern boundary is drawn.
Source: Ocean areas, NOAA; land area, CIA World Factbook
If Mount Everest were dropped into the deepest part of the Mariana Trench, how much water would be above it?
About 2 km
Everest is 8,849 m tall and Challenger Deep is about 10,935 m down. 10,935 - 8,849 is about 2,086 m, so roughly two kilometres of water would still be overhead.
Source: Everest height, Nepal and China joint survey 2020; Challenger Deep, NOAA
How does the Sahara compare in area to the United States?
They are about the same
The Sahara is about 9.2 million km2 and the United States about 9.8 million km2, close enough that the desert would blanket the entire country.
Source: Sahara extent, Encyclopaedia Britannica; US area, CIA World Factbook
Roughly how much land does the average person in Mongolia have to themselves?
About 50 hectares
Mongolia is about 1.56 million km2 with about 3.5 million people, giving about 0.45 km2 each. A km2 is 100 hectares, so roughly 45 to 50 hectares per person, the lowest population density of any sovereign country.
Source: Area and population, World Bank
Roughly how many football pitches would cover Vatican City?
About 70
Vatican City is about 0.49 km2, or 490,000 m2. A pitch is roughly 7,000 m2, so about 70 of them.
Source: Vatican area from the Holy See; FIFA pitch dimensions
Walking non-stop at a steady pace, roughly how long would it take to cover the Earth's circumference?
About a year
The equator is about 40,075 km. At 5 km/h without stopping that is roughly 8,000 hours, or about 11 months of continuous walking.
Source: WGS84 equatorial circumference; typical walking speed
Which is larger: grains of sand in the Sahara, or stars in the observable universe?
Stars, by a wide margin
The Sahara holds very roughly 1e21 grains. Estimates of stars in the observable universe run to 1e22 or more, so the old saying has it backwards for a single desert.
Source: Standard order-of-magnitude estimates; Hubble deep field star counts
If every person on Earth stood shoulder to shoulder, roughly how much space would they need?
About the area of Los Angeles
At about four people per square metre, 8 billion people need about 2,000 km2. Los Angeles is roughly 1,300 km2 and Greater London about 1,600.
Source: World population from the UN; standard crowd-density figures
Driving at motorway speed without stopping, roughly how long to cover the distance to the Moon?
About six months
The Moon averages about 384,400 km away. At 100 km/h that is 3,844 hours, or about 160 days of continuous driving.
Source: Mean Earth-Moon distance, NASA
How many times would Texas fit inside Alaska?
About twice
Alaska is roughly 1.72 million km2 and Texas about 0.69 million, so a little over two and a half times. Alaskans reportedly enjoy pointing this out.
Source: US Census Bureau state areas
How does the European Union compare in area with the United States?
The EU is under half the size
The EU covers roughly 4.2 million km2 against the United States' 9.8 million (under half) while holding about 450 million people to America's 335 million.
Source: Eurostat; US Census Bureau
On a Mercator map Greenland looks about the size of Africa. What is the real ratio?
Africa is 14 times larger
Greenland is about 2.17 million km2 and Africa about 30.4 million. Mercator inflates area with latitude, and Greenland sits very far north.
Source: Standard areas; Mercator projection distortion
Which is larger: the surface area of Russia, or of Pluto?
Pluto, but only just
Pluto's surface is about 17.7 million km2 and Russia about 17.1 million. One country is nearly the size of a dwarf planet.
Source: NASA New Horizons measurements; CIA World Factbook
How does the Amazon basin compare in area with the European Union?
The basin is larger
The Amazon basin covers roughly 7 million km2 against the EU's 4.2 million. Roughly 60 percent of the basin lies in Brazil.
Source: Amazon Cooperation Treaty Organization; Eurostat
Roughly how long is Chile from north to south?
About 4,300 km
Chile stretches roughly 4,300 km while averaging only about 180 km wide. Laid over Europe it would reach from Norway to North Africa.
Source: Instituto Geografico Militar de Chile
Indonesia spans roughly the same east-west distance as which?
London to Kabul
Indonesia stretches about 5,100 km, comparable to London-Kabul. It spans three time zones and over 17,000 islands.
Source: Statistics Indonesia; great-circle distances