Sobre Cifra

Qué es esto

Un juego diario sobre las cifras que describen el mundo real: cuánta gente vive en un sitio, cuánto cuesta algo, a qué distancia está la Luna. Estimas, descubres lo cerca que estabas y, con suerte, aprendes algo que se te queda.

Es gratis, no necesita cuenta y funciona en cualquier móvil. Todavía no hay clasificaciones ni funciones sociales. Solo cinco preguntas al día.

Cómo se eligen las cifras

Un dato solo entra en el juego si supera cuatro filtros:

1. Es verificable. Una fuente con nombre y enlace, no un «según los estudios».
2. Es estable. Fuera cotizaciones y tipos de cambio: estarían mal antes de que terminaras de leer. Dentro, cifras que se mueven despacio o que están fijadas a un año concreto.
3. Es interesante. Las mejores preguntas son aquellas en las que una persona razonable falla por un factor de tres y no se lo cree.
4. No es ambigua. «Población de Nueva York» significa los cinco distritos, y la página lo dice.

Cuando una cifra está realmente en disputa

Algunas cifras —muertos en una guerra, cuánta gente ha vivido en total— son estimaciones con márgenes de error enormes, y la página lo dice y explica por qué. Nunca nos inventamos una precisión que no tenemos.

Fuentes que se usan actualmente

549 fuentes distintas en 671 preguntas.

• AIDA International records
• AMC
• ANSI/USB HID keyboard standard, as documented by keyboard manufacturers
• ASCII Media Works, Sword Art Online light novel
• 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
• American Pet Products Association
• American Red Cross
• Anime News Network, industry broadcast calendar
• Apple CEO Tim Cook (Q3 FY2025 earnings call), as reported by TechCrunch
• Apple Corps official discography
• Apple and Samsung battery service documentation
• Apple annual report (Form 10-K)
• Apple newsroom
• Apple, 2025 App Store Transparency Report
• 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
• Bandai, Digimon franchise
• Base de Datos Española de Composición de Alimentos (BEDCA)
• Bianconi et al., Annals of Human Biology
• Billboard
• Billboard Canada
• Billboard chart archives
• Bitcoin protocol specification
• Bodas.net Informe del Sector Nupcial 2026
• Boletín Oficial del Estado (Real Decreto 126/2026)
• Bones Studio
• 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
• ByteDance disclosures and industry estimates
• ByteDance disclosures and third-party estimates
• CBS
• CBS News, reporting RM Sotheby’s sale result
• CD Projekt investor reports
• CDC National Center for Health Statistics
• CIA World Factbook
• CIA World Factbook historical records / UN membership archives
• CLAMP, Cardcaptor Sakura manga
• CMS National Health Expenditure Accounts
• California Association of Realtors
• Cambridge Bitcoin Electricity Consumption Index
• Carnegie Hall, classical music resources
• Catalogue of Life
• Centers for Disease Control and Prevention
• Centre National Interprofessionnel de l’Economie Laitière (CNIEL)
• Chess.com board report, Q1 2026
• 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
• Consumer Technology Association, UHD display standard
• 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
• Delta Dental, Original Tooth Fairy Poll
• 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
• ESA Space Debris Office
• ESPN
• Egyptian Ministry of Tourism and Antiquities
• Eiffel Tower official website (toureiffel.paris)
• Electronic Arts investor disclosures
• Emaar Properties, official Burj Khalifa site
• Empire State Realty Trust
• Encyclopaedia Britannica
• Encyclopaedia Britannica / historical demography research
• Entertainment Software Association / Limelight State of Online Gaming
• Eon Productions
• Epic Games
• Epic Games announcements
• Esports Charts
• Esports Earnings / Valve tournament data
• Ethnologue
• European Broadcasting Union
• European Broadcasting Union, Eurovision Song Contest
• 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
• European Union
• Eurostat
• Eurostat energy price statistics
• Eurostat household budget survey
• Eurostat labour force survey
• FBI Uniform Crime Reporting Program
• FC Barcelona
• FIDE, World Chess Federation, Laws of Chess
• FIFA
• FIFA Big Count
• FIFA Big Count survey
• FIFA Laws of the Game
• 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
• France Football
• Fédération Internationale de Volleyball (FIVB)
• GPS.gov, official U.S. government GPS information site
• GSM standard for Short Message Service (3GPP)
• GSMA Intelligence
• Google
• Google (The Keyword blog)
• 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
• Guinness World Records — Most valuable virtual object
• HBO
• HBO viewership figures
• Hasbro / Guinness World Records
• Hasbro, official Monopoly rules
• Hasbro, official Scrabble rules
• Have I Been Pwned aggregate breach data
• Hedges & Company vehicle registration analysis
• Historic Royal Palaces
• Holy See
• Holy See Press Office
• Hostelería de España annual report
• How To Market A Game (Chris Zukowski), VG Insights data
• HowLongToBeat community data
• IAAF biomechanics report, 2009 Berlin World Championships
• IBM archives
• IDC Global DataSphere
• IDC Worldwide Quarterly Mobile Phone Tracker
• IFPI Global Music Report
• IFPI, Engaging with Music 2023
• INDEC Argentina
• INSEE
• ISO/IEC 7812 card numbering standard
• Imperva Bad Bot Report
• Indonesian Geospatial Information Agency
• InnerSloth developer statements
• Instagram Help Center (Meta)
• 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 Astronomical Union
• International Astronomical Union, Minor Planet Center
• International Basketball Federation (FIBA)
• International Bureau of Weights and Measures (BIPM)
• International Cocoa Organization
• International Coffee Organization
• International Cricket Council, Laws of Cricket
• International Energy Agency
• International Energy Agency Global EV Outlook
• International Energy Agency Global EV Outlook 2026
• International Energy Agency, SDG7 Tracking Report
• International Football Association Board (IFAB), Laws of the Game
• International Ice Hockey Federation (IIHF)
• International Monetary Fund World Economic Outlook
• International Monetary Fund World Economic Outlook (April 2026)
• International Olympic Committee
• International Ornithological Congress World Bird List
• International Playing-Card Society
• International Rice Research Institute
• International Telecommunication Union
• International Tennis Federation
• International Tennis Federation, Rules of Tennis
• International Trade Centre commodity data
• International Union of Pure and Applied Chemistry (IUPAC)
• IoT Analytics State of IoT report
• Istituzione per la Conservazione della Gondola e la Tutela del Gondoliere
• Jonathan McDowell, Starlink launch statistics
• Junta Constructora del Temple Expiatori de la Sagrada Família
• Kanzenshuu, Dragon Ball Super episode guide
• Kelley Blue Book average transaction price
• King / Activision Blizzard disclosures
• Kodansha
• Kodansha, Attack on Titan manga
• Kodansha, Sailor Moon manga
• Konami, Yu-Gi-Oh! Official Card Game rules
• Krispy Kreme nutrition information
• LaLiga official attendance data
• League of American Orchestras
• Linux Foundation / kernel source tree
• Loterías y Apuestas del Estado
• Lucasfilm / Disney
• Lucasfilm production records reported by the American Film Institute
• MAPPA / Wit Studio, Attack on Titan anime
• Major League Baseball official rules and Rawlings specifications
• Major League Baseball, Official Baseball Rules
• Major League Eating
• Manufacturer specifications and independent reviews
• McDonald’s Corporation annual report
• McDonald’s USA nutrition information
• McDonald’s corporate statements reported in the trade press
• Meta CEO Mark Zuckerberg, as reported by CNBC
• Meta Community Standards Enforcement Report
• Meta Platforms disclosures
• Meta Platforms disclosures and industry estimates
• Metro de Madrid
• Metropolitan Transportation Authority
• Michelin Guide
• Microsoft investor relations
• Migration Policy Institute / historical migration data
• Ministerio de Agricultura, Pesca y Alimentación (MAPA)
• 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 Transportes y Movilidad Sostenible
• Mojang Studios technical documentation
• Motorola historical product records
• Moviefone (weekend box office report)
• 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 Science
• NASA historical computing specifications
• NBA collective bargaining data reported by Spotrac
• NBC
• NFL salary data compiled by Spotrac
• NOAA National Weather Service Storm Prediction Center
• NOAA Office of Ocean Exploration
• NTV / Madhouse
• NYC Department of City Planning (PLUTO dataset)
• NYC Department of Health permitted food service establishments
• NYC Taxi and Limousine Commission
• National Archives, U.S. Electoral College
• National Association of Music Merchants (NAMM)
• National Association of Theatre Owners
• National Association of Theatre Owners / Motion Picture Association
• National Basketball Association records
• National Basketball Association, Official Rules
• 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 Football League, Official Playing Rules
• National Geographic / peer-reviewed carbon cycle research
• National Geographic Society
• National Honey Board
• National Hot Dog and Sausage Council
• National Human Genome Research Institute
• National Institutes of Health
• National Institutes of Health, MedlinePlus
• National Institutes of Health, MedlinePlus Genetics
• National Institutes of Health, National Heart, Lung, and Blood Institute
• National Oceanic and Atmospheric Administration
• National Park Service
• National Turkey Federation / EatTurkey.org
• National WWII Museum, drawing on national archives
• Nelson Mandela Foundation
• Netcraft Web Server Survey
• Netflix
• 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
• Nintendo IR — dedicated video game sales units
• Nintendo IR — top selling title sales units (Nintendo Switch)
• Nintendo consolidated sales data
• Nintendo corporate information
• NordPass password habits research
• North American Association of State and Provincial Lotteries
• North Atlantic Treaty Organization
• OECD Global Plastics Outlook
• Office for National Statistics
• Oktaviana et al., "Narrative cave art in Indonesia by 51,200 years ago", Nature (2024)
• Ookla Speedtest Global Index
• OpenAI, as reported by TechCrunch
• 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
• RATP Group
• 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, Q2 2026 shareholder letter (SEC Form 8-K, exhibit 99.1)
• Rolling Stone, reporting Christie’s results
• 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
• Scryfall card database
• Seabed 2030 project / GEBCO
• Sega
• Sender, Fuchs & Milo, PLOS Biology
• Shanghai Metro / UITP statistics
• Shannon number, Claude Shannon, Philosophical Magazine
• Shogakukan, Detective Conan / Case Closed manga
• Shueisha / Toei Animation, Dragon Ball franchise
• Shueisha, Bleach manga
• Shueisha, Dragon Ball manga
• Shueisha, JoJo's Bizarre Adventure manga
• Shueisha, Naruto manga
• Shueisha, One Piece manga
• Shueisha, Yu-Gi-Oh! manga
• 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
• South African History Online
• SpaceX published capabilities and services pricing
• Speedrun.com verified leaderboard
• Spices Board of India (DGCI&S data)
• Spotify Loud & Clear royalty report
• Spotify Q2 2026 results (Form 6-K)
• Spotify Wrapped aggregate data
• Spotify company information
• Spotify play counts
• Square Enix, Fullmetal Alchemist manga
• 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
• Statue Cruises, official concessioner (Statue of Liberty National Monument)
• SteamDB achievement statistics
• SteamDB concurrent user tracker (via MP1st)
• SteamDB release data (via Steam Page Analyzer)
• Steinway & Sons technical specifications
• Stiftung Berliner Mauer
• Stockholm International Peace Research Institute (SIPRI)
• Studio Gainax
• Studio Ghibli
• Studio Ghibli official site
• Sunrise Studio
• Supreme Court of the United States
• TOP500 supercomputer rankings, June 2026
• TSMC 2nm (N2) technology page
• TV Tokyo / Studio Pierrot
• Take-Two Interactive Q1 FY2027 results (via Game Developer)
• Take-Two Interactive Q1 fiscal 2027 earnings (reported by Insider Gaming)
• Take-Two Interactive sales disclosures
• Tax Foundation
• Team nutrition data reported by Amaury Sport Organisation
• TeleGeography Submarine Cable Map
• Tesla quarterly production and delivery reports
• The Beatles official archive
• The Coca-Cola Company product information
• The Coca-Cola Company, official nutrition information
• The Economist, Big Mac Index
• The Himalayan Database
• The Knot Real Weddings Study
• The Knot, Jewelry & Engagement Study
• The Lego Group
• The New York Times / creator statements
• The Pokémon Company
• The Pokémon Company International, Pokémon TCG rules
• The Pokémon Company official Pokédex
• The Pokémon Company — Pokémon in Figures
• The R&A / USGA, Rules of Golf
• The Recording Academy
• The Tetris Company
• The White House Historical Association
• TimeAndDate.com, citing Russian federal law
• Times Square Alliance
• Toei Animation
• 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 Agriculture, FoodData Central
• U.S. Department of Agriculture, National Agricultural Statistics Service
• U.S. Department of Energy, Energy Saver guide
• U.S. Department of Energy, Manhattan Project history
• U.S. Department of Labor
• U.S. Department of State
• U.S. Department of State, Office of the Historian
• U.S. Department of Transportation
• 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. House of Representatives, History, Art & Archives
• U.S. Metric Association
• U.S. National Archives
• U.S. National Park Service
• U.S. National WWII Museum
• U.S. Office of Personnel Management
• U.S. Office of the Historian, Department of State
• U.S. Senate
• 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 DESA, World Urbanization Prospects 2025
• 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 Office of the High Representative for LDCs, LLDCs and SIDS
• UN Tourism (UNWTO)
• UNCTAD / Statista e-commerce statistics
• UNEP Food Waste Index Report
• UNESCO
• 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
• Ufotable, Demon Slayer anime
• Unicode Consortium
• United Nations
• United Nations / Maddison Project historical estimates
• United Nations Environment Programme, Mediterranean Action Plan
• United Nations World Urbanization Prospects
• United Nations, World Population Prospects
• United States Mint
• United States Postal Service
• 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
• Venice Tourism Board (comune.venezia.it)
• Verisign Domain Name Industry Brief
• Virgin Galactic, Q4 and full-year 2025 results and business update
• Visa Inc. annual report
• Visual Effects Society industry data
• W3Techs, Usage Statistics of Content Management Systems
• Wall Street Journal broadcast analysis
• Warner Bros. Pictures
• WarnerMedia and Netflix statements reported in the trade press
• Water Footprint Network
• Wikimedia Foundation
• Wikimedia Foundation statistics
• Wikipedia, List of Marvel Cinematic Universe films
• Wikipedia, List of actors who have played the Doctor
• Wikipedia, List of most-viewed YouTube videos
• Wikipedia, The Simpsons season 37
• World Athletics
• World Athletics competition rules
• World Bank, World Development Indicators (urban population, % of total)
• World Boxing Association / World Boxing Council
• 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 Pool-Billiard Association, official rules
• World Rugby, Laws of the Game
• World Wide Fund for Nature
• X Help Center
• Xbox (CEO Asha Sharma), reported by VGChartz
• YouTube Culture & Trends report
• YouTube Help Center
• YouTube Official Blog
• YouTube press materials
• Zoom Video Communications disclosures
• Zumper National Rent Report
• eMarketer / Backlinko ad blocking research

Correcciones

Las cifras cambian. La población crece, los precios suben, los organismos revisan sus propias estimaciones pasadas. Si un dato de aquí ya no coincide con su fuente, eso es un error y queremos saberlo.

Incluye la URL de la pregunta, la cifra que crees correcta y un enlace a la fuente. Las correcciones se aplican a la página de la pregunta y, si hace falta, se reedita el día afectado.

Escribe a [email protected] y llega a una persona.

Marcas y atribución

Los nombres de empresas, productos y organizaciones se usan de forma descriptiva para identificar el asunto de una pregunta. Cifra no está afiliado, avalado ni patrocinado por ninguno de ellos. Las cifras son hechos y se citan a sus editores; no se reproduce ningún material de origen.