The United States continues to use Fahrenheit primarily due to historical precedent and the high cost of converting infrastructure, education systems, and cultural understanding to a new system. When most countries switched to the metric system (including Celsius) in the mid-20th century, the U.S. considered changing but ultimately decided against mandatory conversion. The Fahrenheit scale also offers slightly more precise whole-number gradations for everyday weather temperatures (a 1°F change is smaller than a 1°C change), which some argue is advantageous for weather forecasting and daily life. Additionally, there’s significant cultural inertia – Americans have an intuitive understanding of what temperatures feel like in Fahrenheit, making change difficult. Despite this, scientific, medical, and many industrial applications in the U.S. do use Celsius, creating a dual-system environment.

Yes, the Fahrenheit and Celsius scales meet at exactly -40 degrees. At this point, -40°F equals -40°C. This mathematical curiosity occurs because of how the two scales are defined. To find this intersection point, we can set the conversion formulas equal to each other: F = C, where F = (C × 9/5) + 32. Solving for this equation: C = (C × 9/5) + 32, which simplifies to -40. This is the only temperature where the numerical value is identical on both scales. At all other temperatures, conversion between the scales is necessary. This interesting point is well below the freezing point of water and represents extremely cold conditions that would be dangerous without proper protection.

Neither Fahrenheit nor Celsius is inherently more precise as a scale – both can be measured to any degree of precision needed by using decimal places. However, if we consider only whole-number increments, Fahrenheit does provide finer gradation because each Fahrenheit degree represents a smaller temperature change than each Celsius degree. Specifically, one degree Fahrenheit equals 5/9 of a degree Celsius. This means that the Fahrenheit scale divides the range between freezing and boiling points of water into 180 increments, while Celsius uses 100 increments for the same range. In everyday use like weather forecasting, this finer gradation in Fahrenheit can sometimes be convenient, though in practice, decimal places in Celsius (like 21.5°C) easily provide equivalent precision when needed. In scientific contexts where extreme precision is required, scientists often use Kelvin anyway, which has the same increment size as Celsius.

When baking with international recipes, accurate temperature conversion is crucial for success. American recipes typically list oven temperatures in Fahrenheit, while European and most international recipes use Celsius. For conversion, you can use our calculator above or follow these common baking temperature equivalents: Warm oven (325°F = 165°C), Moderate oven (350°F = 175°C), Hot oven (400°F = 200°C), Very hot oven (450°F = 230°C). It’s worth noting that many international recipes use standardized terms like “moderate oven” alongside the temperature, which can help verify your conversion is appropriate. Also, remember that fan-forced/convection ovens typically require temperatures about 20°F/10°C lower than conventional ovens. For precision baking like pastries and soufflés, exact temperature is critical, so using a precise conversion rather than a rough estimate is recommended. If your oven has a digital display that can switch between scales, this is the easiest solution.

The Celsius and Kelvin scales have a direct linear relationship – they use the same size degree increments, but start at different zero points. Kelvin is the standard unit of temperature in the International System of Units (SI) and is used extensively in scientific applications. The Kelvin scale starts at absolute zero, the theoretical temperature at which all thermal motion stops, which is -273.15°C. To convert from Celsius to Kelvin, you simply add 273.15 to the Celsius temperature: K = °C + 273.15. Conversely, to convert from Kelvin to Celsius, subtract 273.15: °C = K – 273.15. Unlike Celsius and Fahrenheit, Kelvin doesn’t use the degree symbol (°) – temperatures are simply expressed as “K”. For example, water freezes at 273.15 K and boils at 373.15 K at standard pressure. Scientists prefer the Kelvin scale because it doesn’t have negative values and directly relates to the energy in a system, making it ideal for thermodynamic calculations.