🌡 Understanding the Three Temperature Scales
Celsius (°C)
Used by almost all countries worldwide. Based on water’s freezing point (0°C) and boiling point (100°C) at sea level atmospheric pressure. Part of the metric system.
Fahrenheit (°F)
Primarily used in the United States and a few territories. Water freezes at 32°F and boils at 212°F. Created by Daniel Gabriel Fahrenheit in 1724, originally based on a brine solution freezing point.
Kelvin (K)
The scientific standard used in physics, chemistry, and astronomy. Starts at absolute zero (0K = -273.15°C), the theoretical point where all molecular motion ceases. No negative values exist in the Kelvin scale.
🏥 Body Temperature Reference — Detailed Guide
| Condition | Celsius | Fahrenheit |
| Hypothermia (severe) | Below 32°C | Below 90°F |
| Low body temp | 35-36°C | 95-96.8°F |
| Normal range | 36.1-37.2°C | 97-99°F |
| Low-grade fever | 37.3-38°C | 99.1-100.4°F |
| Fever | 38.1-39°C | 100.6-102.2°F |
| High fever | Above 39°C | Above 102.2°F |
⚠ This is general reference information, not medical advice. Consult a doctor for fever management, especially in infants, elderly, or with persistent high temperatures.
🌡 Climate and Regional Temperature Context
Understanding temperature in context helps when planning travel or interpreting weather across different countries that use different scales.
| Climate Type | Typical Summer Range (°C) | Typical Summer Range (°F) |
| Tropical (e.g., Mumbai) | 28-35°C | 82-95°F |
| Desert (e.g., Dubai) | 35-45°C | 95-113°F |
| Temperate (e.g., London) | 15-25°C | 59-77°F |
| Continental (e.g., Chicago) | 20-32°C | 68-90°F |
| Mediterranean (e.g., Rome) | 25-35°C | 77-95°F |
Quick Mental Conversion Tricks
- Celsius to Fahrenheit (approximate): Double the Celsius value and add 30 (e.g., 20°C × 2 + 30 = 70°F, actual is 68°F — close enough for quick estimates)
- Fahrenheit to Celsius (approximate): Subtract 30, then divide by 2 (e.g., 70°F − 30 = 40, ÷ 2 = 20°C — matches well)
Related Calculators
❓ Frequently Asked Questions
How do you convert Celsius to Fahrenheit? +
Formula: F = (C × 9/5) + 32. Example: 25°C = (25 × 9/5) + 32 = 45 + 32 = 77°F.
How do you convert Fahrenheit to Celsius? +
Formula: C = (F – 32) × 5/9. Example: 98.6°F = (98.6 – 32) × 5/9 = 66.6 × 5/9 = 37°C.
What is absolute zero? +
Absolute zero is -273.15°C (0 Kelvin), the theoretical temperature at which all molecular motion stops. It is the coldest possible temperature and cannot be physically achieved, only approached.
Why does the US use Fahrenheit while most countries use Celsius? +
The US retained Fahrenheit from British colonial influence, while the UK and most other countries switched to Celsius (part of the metric system) in the mid-20th century for scientific and international standardization.
What is normal human body temperature? +
Normal human body temperature is approximately 37°C (98.6°F), though it can range from 36.1-37.2°C (97-99°F) depending on time of day and individual variation.
What temperature does water boil and freeze? +
Water freezes at 0°C (32°F, 273.15K) and boils at 100°C (212°F, 373.15K) at standard atmospheric pressure (sea level).