About - Franz Fahrenheit

My Story

Hi, I'm Björn Schefzyk, the creator of Franz Fahrenheit. When I first moved to the United States, I was constantly struggling with Fahrenheit temperatures. Coming from Germany where we use Celsius, I found myself constantly doing mental math or reaching for conversion apps every time I checked the weather.

One day, frustrated after yet another failed attempt to quickly understand if 72°F was warm enough for shorts, I thought: "Why is there no weather app that shows both temperatures at the same time?" Sure, a few apps existed that claimed to do this, but they were either poorly designed, hard to use, or just plain ugly.

So I decided to make a good one myself. I wanted something clean, beautiful, and that would instantly show me both Celsius and Fahrenheit without any tapping, swiping, or converting. Franz Fahrenheit was born from this simple need.

Today, Franz Fahrenheit has become the most popular and highly rated app for dual-temperature weather display on the App Store. It's currently available for iOS and as this web app, with Android potentially coming soon. Even though I've since moved back to Berlin, I still use and love the app daily, and I'm constantly inspired by feedback from users who, like me, have moved between countries and need to adapt to different temperature scales.

For weather data, Franz Fahrenheit uses Apple WeatherKit and The Weather Company to ensure you get the most accurate and up-to-date information, displayed in the way that makes sense for your life.

The History of Temperature Scales

🌡️ Celsius Scale

Invented by: Anders Celsius (Swedish astronomer)

Year: 1742

Originally: Celsius actually proposed the reverse scale, with 100° as the freezing point of water and 0° as the boiling point. This was later inverted to the scale we know today.

Based on: Water's freezing point (0°C) and boiling point (100°C) at standard atmospheric pressure

Usage: Used by most of the world (about 95% of countries) and is the standard in science

🌡️ Fahrenheit Scale

Invented by: Daniel Gabriel Fahrenheit (German-Dutch physicist)

Year: 1724

Based on: Originally three reference points: the temperature of a mixture of ice, water, and ammonium chloride (0°F), the freezing point of water (32°F), and human body temperature (originally 96°F, later adjusted to 98.6°F)

Unique aspect: Fahrenheit chose his scale to avoid negative numbers in everyday weather, as his 0°F was the coldest temperature he could reliably create in his lab

Usage: Primarily used in the United States, Belize, and a few Caribbean nations

🤔 Interesting Facts

Why 32°F for freezing? Fahrenheit's scale was designed around his three reference points, making water's freezing point fall at 32°F rather than a round number
Scientific preference: Scientists worldwide use Celsius (or Kelvin for absolute measurements) because it's based on decimal increments and water's phase changes
Weather reporting: Fahrenheit actually provides more precision for everyday weather temperatures - the range of typical weather (0°F to 100°F) covers more degrees than Celsius (-18°C to 38°C)
Global adoption: The US is one of only three countries that haven't officially adopted the metric system, which is why Fahrenheit persists there
Conversion formula: °F = (°C × 9/5) + 32, or °C = (°F - 32) × 5/9

Why Both Scales Matter

In our increasingly connected world, millions of people travel, relocate, or work internationally. Whether you're an American visiting Europe, a European living in the US, or someone who simply wants to understand weather reports from different parts of the world, having both temperature scales readily available eliminates confusion and makes weather information truly universal.