CHALLENGE
Fermi Friends Challenge
Send a code, play the same five Fermi questions and see who gets closest. Hard mode: 20 seconds each, no calculator.
Fermi: Daily Guessing Game
Estimate anything in 3 minutes
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Fermi is a daily game about getting close.
Every morning you get three questions nobody can answer off the top of their head. How many baguettes do the bakeries of Paris sell before noon? How many trees are standing on Earth right now? You don't look it up. You break the problem into pieces you already know, follow a hunch, and put a number on it.
Then you find out how close you landed.
HOW IT WORKS
• Three questions. About three minutes.
• One number per question — no multiple choice, no second tries.
• Your score is the multiple between your answer and the truth. 1x is spot on. Lower is better.
• See where your number sits against everyone else who played today.
WHY IT'S DIFFERENT
Most quiz apps reward what you already memorised. This one rewards how you think. The physicist Enrico Fermi was famous for landing within an order of magnitude of almost anything using nothing but reasoning — how many piano tuners work in Chicago, how much energy a blast released judging by how far the paper scraps flew. That is the skill this app trains, and it gets sharper the more you use it.
WHAT YOU GET
• A fresh set of three questions every morning
• A daily leaderboard, plus weekly and monthly standings
• Your personal best and a running history of every round
• An archive of past days, open whenever you want another round
• The sources behind every answer, so you can see where the number came from
• Metric or imperial units, your choice
No sign-up, no email address, no ads in the middle of a question. Your first round is free; a subscription unlocks every daily round, the archive and the working behind every answer.
Come back tomorrow. There is always another one.
Terms of Use (Apple Standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://fermi.begtools.xyz/privacy
Questions or feedback: cytools85@gmail.com
Events
Ratings & Reviews
New: Play with friends. Start a game, send the code, and everyone answers the same five questions in their own time. Then see who got closest, question by question.
New: Hard mode. 20 seconds a question, no calculator. Pure instinct.
Fermi now also speaks Turkish, German, Spanish and Dutch. It follows your iPhone's language, or pick one under You > Preferences.
The developer, ZEYNEP CEREN GEMICI, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- ZEYNEP CEREN GEMICI
- Size
- 45.5 MB
- Category
- Trivia
- Compatibility
Requires iOS 16.4 or later.
- iPhone
Requires iOS 16.4 or later. - iPad
Requires iPadOS 16.4 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 4 more
- English, Dutch, German, Spanish, Turkish
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Fermi Subscriber Annual $34.99
- Fermi Subscriber Weekly $5.99
- Copyright
- 2026 © Zeynep Ceren Gemici