About Cifra

Guess real-world numbers.

What this is

A daily game about the numbers that describe the real world — how many people live somewhere, what something costs, how far away the Moon is. You estimate, you find out how close you were, and ideally you learn something that sticks.

It is free, needs no account, and works on any phone. There are no leaderboards yet and no social features. Just five questions a day.

How numbers are chosen

A figure only makes it into the game if it clears four tests:

It is verifiable. A named, linkable source — not “studies show”.
It is stable. Stock prices and exchange rates are out; they would be wrong before you finished reading. Figures that move slowly, or are pinned to a stated year, are in.
It is interesting. The best questions are the ones where a reasonable person is off by a factor of three and cannot believe it.
It is unambiguous. “Population of New York City” means the five boroughs, and the page says so.

When a number is genuinely contested

Some figures — deaths in a war, how many people have ever lived — are estimates with wide error bars, and the page says so and explains why. Precision we do not have is never invented.

Sources currently used

415 distinct sources across 500 questions.

AIDA International records
Academic web-scale measurement studies
Academy of Motion Picture Arts and Sciences
Academy of Motion Picture Arts and Sciences filmography records
Ajuntament de Barcelona / INE
All England Lawn Tennis Club
Alphabet annual report (Form 10-K)
Amaury Sport Organisation
Amazon Studios spending reported in the trade press
Amazon disclosures and logistics industry analysis
American Heart Association
American Lung Association
Annuario Pontificio, Holy See
Apple Corps official discography
Apple and Samsung battery service documentation
Apple annual report (Form 10-K)
Apple developer and App Store transparency disclosures
Apple financial disclosures and industry estimates
Apple newsroom
Archivo General de Indias / Encyclopaedia Britannica
Asociación de Promotores Musicales (APM), Anuario de la Música en Vivo
Association of Tennis Professionals match data
Association of Tennis Professionals records
Association of Tennis Professionals shot tracking
Asurio / Reviews.org annual phone habits survey
Ayuntamiento de Madrid
Azevedo et al., Journal of Comparative Neurology
BBC
Bandai Namco historical sales figures
Base de Datos Española de Composición de Alimentos (BEDCA)
Bianconi et al., Annals of Human Biology
Billboard chart archives
Bitcoin protocol specification
Bodas.net Libro Blanco de las Bodas
Box Office Mojo
Brazilian Institute of Geography and Statistics (IBGE)
British Board of Trade inquiry, 1912
British Heart Foundation
British Library
British Museum
Brookings Institution, updating USDA methodology
Brown et al., Language Models are Few-Shot Learners
Brumm et al., Science Advances
ByteDance disclosures and industry estimates
ByteDance disclosures and third-party estimates
CD Projekt investor reports
CDC National Center for Health Statistics
CIA World Factbook
CIA World Factbook historical records / UN membership archives
CMS National Health Expenditure Accounts
California Association of Realtors
Cambridge Bitcoin Electricity Consumption Index
Catalogue of Life
Centre National Interprofessionnel de l’Economie Laitière (CNIEL)
Chess.com and Lichess published statistics
Child Care Aware of America
Chinese State Administration of Cultural Heritage survey
Christie’s auction results
City of Amsterdam
City of Amsterdam mobility statistics
City of Munich official Oktoberfest report
Coldiretti / Italian food industry association data
College Board, Trends in College Pricing
Comune di Venezia
Comune di Venezia tourism statistics
Constitution of India, Eighth Schedule
Contemporary press accounts and organiser estimates
Contentsquare Digital Experience Benchmark
Cornell Lab of Ornithology
Council on Tall Buildings and Urban Habitat
Crowther et al., Nature
DataReportal Digital 2024 Global Overview Report
DataReportal Digital Global Overview Report
Deloitte Christmas Survey
Derived from Google disclosures and industry estimates
Derived from quartz density and Avogadro’s number
Developer postmortems reported in the games press
Disney production budget disclosures reported in the trade press
EMI / Queen official discography
ESA Planck mission / NASA
Egyptian Ministry of Tourism and Antiquities
Electronic Arts investor disclosures
Encyclopaedia Britannica
Encyclopaedia Britannica / historical demography research
Entertainment Software Association / Limelight State of Online Gaming
Entropia Universe / MindArk transaction records
Eon Productions
Epic Games
Epic Games announcements
Esports Charts
Esports Earnings / Valve tournament data
Ethnologue
European Broadcasting Union
European Central Bank
European Central Bank SPACE study on payment habits
European Commission impact assessment on common chargers
European Commission, Common Agricultural Policy
European Food Safety Authority dietary reference values
European Space Agency
European Space Agency, Gaia mission
Eurostat
Eurostat energy price statistics
Eurostat household budget survey
Eurostat labour force survey
FBI Uniform Crime Reporting Program
FC Barcelona
FIFA
FIFA Big Count
FIFA Big Count survey
FIFA Laws of the Game
FIFA and club official records
FIFA audience report
Federación Española de Asociaciones de Productores Exportadores de Frutas y Hortalizas (FEPEX)
Federación Española de Pádel / industry surveys
Federal Reserve Bank of New York, Household Debt and Credit Report
FishBase
Formula 1 / DHL Fastest Pit Stop Award
Formula 1 official timing records
Fox Broadcasting Company
France Football
GSMA Intelligence
Google
Google / Deloitte Milliseconds Make Millions study
Google I/O developer keynote disclosures
Gray’s Anatomy / standard anatomical reference
GroupM / WARC global advertising forecasts
Guinness World Records
HBO viewership figures
Hasbro / Guinness World Records
Have I Been Pwned aggregate breach data
Hedges & Company vehicle registration analysis
Historic Royal Palaces
Holy See Press Office
Hostelería de España annual report
HowLongToBeat community data
IAAF biomechanics report, 2009 Berlin World Championships
IBM archives
IDC Global DataSphere
IDC Worldwide Quarterly Mobile Phone Tracker
IFPI Engaging with Music report
IFPI Global Music Report
INDEC Argentina
INSEE
Imperva Bad Bot Report
Indonesian Geospatial Information Agency
InnerSloth developer statements
Instagram account statistics
Instituto Nacional de Estadística (INE)
Instituto Nacional de Estadística (INE), Encuesta de Estructura Salarial
Instituto Nacional de Estadística de Bolivia
Instituto Nacional de Estadística y Geografía (INEGI)
Instituto de la Cinematografía y de las Artes Audiovisuales (ICAA)
International Air Transport Association (IATA)
International Basketball Federation (FIBA)
International Bureau of Weights and Measures (BIPM)
International Cocoa Organization
International Coffee Organization
International Energy Agency
International Energy Agency Global EV Outlook
International Energy Agency, SDG7 Tracking Report
International Monetary Fund World Economic Outlook
International Olive Council
International Olympic Committee
International Ornithological Congress World Bird List
International Rice Research Institute
International Telecommunication Union
International Trade Centre commodity data
International Union of Pure and Applied Chemistry (IUPAC)
IoT Analytics State of IoT report
Julien’s Auctions results
Junta Constructora del Temple Expiatori de la Sagrada Família
Kelley Blue Book average transaction price
King / Activision Blizzard disclosures
Krispy Kreme nutrition information
LaLiga official attendance data
League of American Orchestras
Linux Foundation / kernel source tree
Loterías y Apuestas del Estado
Lucasfilm production records reported by the American Film Institute
Major League Baseball official rules and Rawlings specifications
Major League Eating
Manufacturer specifications and independent reviews
Marvel Studios release history
McDonald’s Corporation annual report
McDonald’s USA nutrition information
McDonald’s corporate statements reported in the trade press
Meta Community Standards Enforcement Report
Meta Platforms disclosures
Meta Platforms disclosures and industry estimates
Meta Platforms investor disclosures
Metro de Madrid
Metropolitan Transportation Authority
Michelin Guide
Microsoft investor relations
Migration Policy Institute / historical migration data
Ministerio de Agricultura, Pesca y Alimentación, Informe de consumo alimentario
Ministerio de Ciencia, Innovación y Universidades
Ministerio de Sanidad, Sistema Nacional de Salud
Ministerio de Trabajo y Economía Social
Ministerio de Transportes y Movilidad Sostenible
Mojang Studios / Microsoft
Mojang Studios technical documentation
Motorola historical product records
Museo Nacional del Prado annual report
NASA
NASA / Hubble Deep Field analyses
NASA / U.S. Geological Survey
NASA Exoplanet Archive
NASA Global Hydrology Resource Center
NASA Jet Propulsion Laboratory
NASA historical computing specifications
NBA collective bargaining data reported by Spotrac
NFL salary data compiled by Spotrac
NOAA National Weather Service Storm Prediction Center
NOAA Office of Ocean Exploration
NYC Department of City Planning (PLUTO dataset)
NYC Department of Health permitted food service establishments
NYC Taxi and Limousine Commission
National Basketball Association records
National Bureau of Statistics of China
National Center for Education Statistics
National Chicken Council Wing Report
National Coffee Association, National Coffee Data Trends
National Football League
National Football League international audience figures
National Geographic / peer-reviewed carbon cycle research
National Human Genome Research Institute
National Institutes of Health
National Oceanic and Atmospheric Administration
National WWII Museum, drawing on national archives
Netcraft Web Server Survey
Netflix Top 10 viewing data
Netflix annual report
Netflix corporate information
Netflix quarterly shareholder letter
Network rate cards reported in the trade press
New Line Cinema home video release
Newzoo Global Esports Market Report
Newzoo Global Games Market Report
Nielsen
Nintendo consolidated financial highlights
Nintendo consolidated sales data
Nintendo corporate information
NordPass password habits research
North American Association of State and Provincial Lotteries
OECD Global Plastics Outlook
Office for National Statistics
Ookla Speedtest Global Index
OpenAI announcements
Organización de Consumidores y Usuarios (OCU)
PMQ Pizza Magazine industry census
Panama Canal Authority historical records
Paris Saint-Germain and FC Barcelona official statements
Philippine Statistics Authority
Photutorial photography statistics
Pixar Animation Studios production history
Platform disclosures reported in the trade press
Podcast Index / Apple Podcasts directory data
Pollstar box office data
Population Reference Bureau
Potvin & Levenberg, Communications of the ACM
Premier League broadcast agreements
Prison Policy Initiative
QSR Magazine Drive-Thru Study
RM Sotheby’s auction results
Radicati Group Email Statistics Report
Radiotelevisión Española (RTVE) audience data
Real Academia de la Historia
Recording Academy
Recording Industry Association of America
Riot Games
Roblox Corporation quarterly investor materials
Rubik’s / mathematical group theory
RunRepeat / IAAF global participation analysis
Scheidel, Cambridge Economic History of the Greco-Roman World
Schultheiss et al., PNAS
Scientific American, entomology research summary
Seabed 2030 project / GEBCO
Sender, Fuchs & Milo, PLOS Biology
Shanghai Metro / UITP statistics
Shannon number, Claude Shannon, Philosophical Magazine
Small Arms Survey
Smithsonian Global Volcanism Program
Society of Motion Picture and Television Engineers
Société d’Exploitation de la Tour Eiffel
Sony Interactive Entertainment
Sony Interactive Entertainment product specifications
Sony Music certified sales
Sony Music, reported in the trade press
Sophos / industry threat reports
SpaceX / Jonathan McDowell satellite catalogue
SpaceX published capabilities and services pricing
Speedrun.com verified leaderboard
Spices Board of India
Spotify Loud & Clear royalty report
Spotify Wrapped aggregate data
Spotify company information
Spotify play counts
Spotify quarterly investor report
Standard Western music theory
Stanford AI Index Report
Starbucks Corporation annual report
Starbucks U.S. nutrition information
Statista / Grand View Research market analysis
Statista / Kaspersky spam and phishing reports
Statista / e-commerce platform aggregate data
Statista Market Insights
Statistics Bureau of Japan
SteamDB
SteamDB achievement statistics
SteamDB concurrent user tracker
SteamDB release statistics
Steinway & Sons technical specifications
Stiftung Berliner Mauer
Stockholm International Peace Research Institute (SIPRI)
TOP500 supercomputer rankings
TSMC technology roadmap
Take-Two Interactive earnings reports
Take-Two Interactive sales disclosures
Team nutrition data reported by Amaury Sport Organisation
TeleGeography Submarine Cable Map
Tesla quarterly production and delivery reports
The Coca-Cola Company product information
The Himalayan Database
The Knot Real Weddings Study
The Lego Group
The New York Times / creator statements
The Pokémon Company
The Pokémon Company official Pokédex
The Tetris Company
Times Square Alliance
Tokyo Hire-Taxi Association
Tokyo Metropolitan Government
Tokyo Metropolitan Government / Shibuya Ward
Tokyo Metropolitan Government transport statistics
Transport for London
Transportation Security Administration
Turisme de Barcelona
TwitchTracker aggregate statistics
Typing research aggregated by Ratatype / academic HCI studies
U.S. Air Force historical records
U.S. Bureau of Labor Statistics, Consumer Expenditure Survey
U.S. Bureau of Transportation Statistics
U.S. Census Bureau
U.S. Census Bureau population estimates
U.S. Census Bureau, Educational Attainment
U.S. Census Bureau, Income in the United States
U.S. Centers for Disease Control and Prevention
U.S. Department of Energy, Manhattan Project history
U.S. Department of Labor
U.S. Department of State, Office of the Historian
U.S. Environmental Protection Agency
U.S. Federal Highway Administration
U.S. Federal Highway Administration, National Bridge Inventory
U.S. Federal Reserve
U.S. Geological Survey
U.S. National Park Service
U.S. Office of Personnel Management
U.S. Social Security Administration
U.S. Treasury, Debt to the Penny
U.S. Treasury, Monthly Treasury Statement
UEFA
UEFA and Premier League tracking data
UEFA ticketing information
UK Tea & Infusions Association
UN Food and Agriculture Organization
UN Food and Agriculture Organization (FAOSTAT)
UN Food and Agriculture Organization food balance sheets
UN Food and Agriculture Organization tea market review
UN Tourism (UNWTO)
UNCTAD / Statista e-commerce statistics
UNEP Food Waste Index Report
UNESCO / Guinness World Records
UNESCO Atlas of the World’s Languages in Danger
UNESCO Institute for Statistics
UNESCO World Heritage Centre
USDA Census of Agriculture
USDA Economic Research Service
USDA Economic Research Service, Food Availability data
USDA FoodData Central
Union of Concerned Scientists / ESA Space Debris Office
United Nations
United Nations / Maddison Project historical estimates
United Nations World Urbanization Prospects
United Nations, World Population Prospects
Universal Music Group / EMI certified and estimated sales
Universal Pictures production history
University of Arizona microbiology research
University of Oxford Saïd Business School, Olympic cost studies
Verisign Domain Name Industry Brief
Virgin Galactic published pricing
Visa Inc. annual report
Visual Effects Society industry data
Wall Street Journal broadcast analysis
WarnerMedia and Netflix statements reported in the trade press
Water Footprint Network
Widely cited industry estimates derived from Google disclosures
Wikimedia Foundation statistics
Wizards of the Coast / Scryfall database
World Athletics
World Athletics competition rules
World Cube Association
World Economic Forum / industry estimates
World Gold Council
World Health Organization
World Health Organization Global Status Report on Road Safety
World Health Organization tobacco statistics
World Health Organization, Make Listening Safe
World Wide Fund for Nature
YouTube Culture & Trends report
YouTube channel statistics
YouTube press materials
Zoom Video Communications disclosures
Zumper National Rent Report
eMarketer / Backlinko ad blocking research

Corrections

Numbers drift. Populations grow, prices rise, agencies revise their own past estimates. If a figure here no longer matches its source, that is a bug and we want to hear about it.

Include the question URL, the figure you believe is correct, and a link to the source. Corrections are applied to the question page and, where needed, the affected day is re-issued.

Contact details go here before launch — see the deployment checklist in the README.

Trademarks and attribution

Company, product and organisation names are used descriptively to identify the subject of a question. Cifra is not affiliated with, endorsed by, or sponsored by any of them. Figures are facts and are cited to their publishers; no source material is reproduced.