Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin temperature scales.
Common Reference Points
Related Calculators
About This Calculator
The Temperature Converter instantly converts between Fahrenheit, Celsius, and Kelvin with precision and ease. Whether you're checking weather forecasts while traveling abroad, following a recipe from another country, monitoring a fever, or working on scientific calculations, understanding temperature conversions is essential in our globally connected world. The United States, along with a few other nations, uses Fahrenheit for everyday temperature measurement, while the rest of the world and all scientific disciplines use Celsius. Kelvin, starting at absolute zero, is the standard in physics, chemistry, and astronomy. This converter handles all common scenarios: converting weather temperatures when planning international travel, adjusting oven temperatures for recipes from British or European cookbooks, understanding body temperature readings in different units, and performing precise scientific calculations. With instant bidirectional conversion and reference charts for common temperatures, you'll never be confused by temperature scales again. The relationship between Fahrenheit and Celsius dates back to the 18th century, and while the formulas are straightforward, having a quick converter eliminates calculation errors and saves time in everyday situations.
How to Use the Temperature Converter
- 1Enter any temperature value in the Fahrenheit, Celsius, or Kelvin field.
- 2Watch as all other temperature scales update automatically in real-time.
- 3Use the clear button to reset all fields for a new conversion.
- 4Reference the common temperature tables below for quick comparisons.
- 5For cooking, remember that most European recipes use Celsius.
- 6For weather, note that Celsius is used by most countries worldwide.
- 7For science applications, Kelvin is preferred for absolute measurements.
- 8Bookmark this page for quick access when traveling or cooking.
Complete Temperature Conversion Formulas
Fahrenheit to Celsius:
°C = (°F - 32) × 5/9
°C = (°F - 32) ÷ 1.8
Celsius to Fahrenheit:
°F = (°C × 9/5) + 32
°F = (°C × 1.8) + 32
Celsius to Kelvin:
K = °C + 273.15
Kelvin to Celsius:
°C = K - 273.15
Fahrenheit to Kelvin:
K = (°F - 32) × 5/9 + 273.15
Kelvin to Fahrenheit:
°F = (K - 273.15) × 9/5 + 32
Key Constant: The offset between Celsius and Kelvin is exactly 273.15 degrees.
Quick Reference: Fahrenheit to Celsius Chart
Common Temperature Conversions:
| Fahrenheit | Celsius | Description |
|---|---|---|
| -40°F | -40°C | Same in both scales! |
| 0°F | -18°C | Very cold winter day |
| 14°F | -10°C | Cold winter day |
| 32°F | 0°C | Water freezes |
| 41°F | 5°C | Refrigerator temp |
| 50°F | 10°C | Cool autumn day |
| 59°F | 15°C | Mild day |
| 68°F | 20°C | Room temperature |
| 72°F | 22°C | Comfortable room |
| 77°F | 25°C | Warm day |
| 86°F | 30°C | Hot summer day |
| 95°F | 35°C | Very hot day |
| 98.6°F | 37°C | Human body temp |
| 100°F | 37.8°C | Slight fever |
| 104°F | 40°C | High fever |
| 113°F | 45°C | Extreme heat |
| 212°F | 100°C | Water boils |
Every 9°F = 5°C (This ratio is exact and useful for mental math)
Weather Temperature Guide by Country
How Weather Feels in Celsius:
| Celsius | Fahrenheit | Weather Description |
|---|---|---|
| -20°C to -10°C | -4°F to 14°F | Dangerously cold, frostbite risk |
| -10°C to 0°C | 14°F to 32°F | Very cold, winter clothing essential |
| 0°C to 10°C | 32°F to 50°F | Cold, jacket required |
| 10°C to 15°C | 50°F to 59°F | Cool, light jacket |
| 15°C to 20°C | 59°F to 68°F | Mild, comfortable |
| 20°C to 25°C | 68°F to 77°F | Pleasant, shirtsleeve weather |
| 25°C to 30°C | 77°F to 86°F | Warm, summer weather |
| 30°C to 35°C | 86°F to 95°F | Hot, stay hydrated |
| 35°C to 40°C | 95°F to 104°F | Very hot, heat warning |
| 40°C+ | 104°F+ | Extreme heat, dangerous |
International Weather Forecasts: Most weather apps show both scales, but local forecasts in:
- USA, Bahamas, Cayman Islands, Liberia: Fahrenheit
- Everywhere else: Celsius
Cooking Temperature Conversions
Oven Temperature Guide:
| Description | Fahrenheit | Celsius | Gas Mark |
|---|---|---|---|
| Very low | 250°F | 120°C | 1/2 |
| Low | 275°F | 135°C | 1 |
| Low | 300°F | 150°C | 2 |
| Moderately low | 325°F | 165°C | 3 |
| Moderate | 350°F | 175°C | 4 |
| Moderate | 375°F | 190°C | 5 |
| Moderately hot | 400°F | 200°C | 6 |
| Hot | 425°F | 220°C | 7 |
| Very hot | 450°F | 230°C | 8 |
| Extremely hot | 475°F | 245°C | 9 |
| Broiling | 500°F+ | 260°C+ | 10 |
Cooking Liquid Temperatures:
| State | Fahrenheit | Celsius |
|---|---|---|
| Room temp | 68-72°F | 20-22°C |
| Warm | 95-105°F | 35-40°C |
| Tepid | 105-115°F | 40-46°C |
| Simmer | 180-200°F | 82-93°C |
| Gentle boil | 205-210°F | 96-99°C |
| Full boil | 212°F | 100°C |
| Deep frying | 350-375°F | 175-190°C |
Meat Doneness (Internal Temperature):
| Doneness | Fahrenheit | Celsius |
|---|---|---|
| Rare | 125°F | 52°C |
| Medium-rare | 135°F | 57°C |
| Medium | 145°F | 63°C |
| Medium-well | 155°F | 68°C |
| Well-done | 165°F | 74°C |
Body Temperature and Health
Normal Body Temperature Ranges:
| Measurement Method | Fahrenheit | Celsius | Notes |
|---|---|---|---|
| Oral (under tongue) | 97.6-99.6°F | 36.4-37.6°C | Most common |
| Rectal | 98.6-100.4°F | 37-38°C | Most accurate |
| Armpit (axillary) | 96.6-98.0°F | 35.9-36.7°C | Lower reading |
| Ear (tympanic) | 97.6-99.6°F | 36.4-37.6°C | Quick reading |
| Forehead (temporal) | 97.4-99.6°F | 36.3-37.6°C | Non-invasive |
Fever Classification:
| Category | Fahrenheit | Celsius | Action |
|---|---|---|---|
| Normal | 97-99°F | 36.1-37.2°C | No concern |
| Low-grade fever | 99-100.4°F | 37.2-38°C | Monitor |
| Fever | 100.4-102°F | 38-38.9°C | Rest, fluids |
| High fever | 102-104°F | 38.9-40°C | Consider doctor |
| Very high fever | 104°F+ | 40°C+ | Seek medical care |
| Dangerous | 106°F+ | 41.1°C+ | Emergency |
Hypothermia Stages:
| Stage | Fahrenheit | Celsius | Symptoms |
|---|---|---|---|
| Mild | 90-95°F | 32-35°C | Shivering, confusion |
| Moderate | 82-90°F | 28-32°C | Drowsiness, weak pulse |
| Severe | Below 82°F | Below 28°C | Loss of consciousness |
Mental Math Shortcuts for Temperature
Quick Fahrenheit to Celsius (Approximate):
- Subtract 30 from the Fahrenheit temperature
- Divide the result by 2
- Result is close to Celsius
Examples:
- 70°F → (70-30)/2 = 20°C ✓ (Actual: 21.1°C)
- 90°F → (90-30)/2 = 30°C ✓ (Actual: 32.2°C)
- 50°F → (50-30)/2 = 10°C ✓ (Actual: 10°C - exact!)
Quick Celsius to Fahrenheit (Approximate):
- Double the Celsius temperature
- Add 30
Examples:
- 20°C → (20×2)+30 = 70°F ✓ (Actual: 68°F)
- 30°C → (30×2)+30 = 90°F ✓ (Actual: 86°F)
- 10°C → (10×2)+30 = 50°F ✓ (Actual: 50°F - exact!)
Reference Points to Memorize:
| Fahrenheit | Celsius | Memory Trick |
|---|---|---|
| 32°F | 0°C | Water freezes |
| 50°F | 10°C | Cool day |
| 68°F | 20°C | Room temp |
| 86°F | 30°C | Hot day |
| 104°F | 40°C | Heat wave |
The 10-Degree Rule: Every 10°C equals 18°F. Use this for quick adjustments from known points.
Scientific Temperature Reference
Important Scientific Temperatures:
| Description | Kelvin | Celsius | Fahrenheit |
|---|---|---|---|
| Absolute zero | 0 K | -273.15°C | -459.67°F |
| Helium boils | 4.2 K | -268.95°C | -452.11°F |
| Nitrogen boils | 77 K | -196°C | -320.8°F |
| Oxygen boils | 90 K | -183°C | -297.4°F |
| Dry ice sublimates | 195 K | -78.5°C | -109.3°F |
| Water freezes | 273.15 K | 0°C | 32°F |
| Human body | 310 K | 37°C | 98.6°F |
| Water boils | 373.15 K | 100°C | 212°F |
| Paper ignites | 505 K | 232°C | 450°F |
| Lead melts | 600 K | 327°C | 621°F |
| Aluminum melts | 933 K | 660°C | 1220°F |
| Iron melts | 1811 K | 1538°C | 2800°F |
| Sun surface | 5778 K | 5505°C | 9941°F |
| Sun core | 15,000,000 K | ~15M°C | ~27M°F |
Why Kelvin in Science:
- No negative numbers (starts at absolute zero)
- Proportional to actual thermal energy
- Required for gas laws (PV=nRT)
- Standard in physics and chemistry
History of Temperature Scales
The Three Main Scales:
Fahrenheit (1724):
- Created by Daniel Gabriel Fahrenheit (German-Dutch)
- Originally: 0°F = coldest ice/salt mixture he could make
- 96°F = human body temperature (later adjusted to 98.6°F)
- Water freezes at 32°F, boils at 212°F (180-degree range)
- Used in: USA, Bahamas, Cayman Islands, Liberia
Celsius (1742):
- Created by Anders Celsius (Swedish astronomer)
- Originally inverted! (0 = boiling, 100 = freezing)
- Carl Linnaeus reversed it after Celsius's death
- Water freezes at 0°C, boils at 100°C (100-degree range)
- Used in: All other countries and all science
Kelvin (1848):
- Proposed by Lord Kelvin (William Thomson, Scottish)
- Starts at absolute zero: coldest possible temperature
- Same increment size as Celsius
- 0 K = -273.15°C = -459.67°F
- Used in: All scientific applications
Other Historical Scales:
- Réaumur (1730): 0°Ré = freezing, 80°Ré = boiling
- Rankine (1859): Like Kelvin but using Fahrenheit increments
- Newton (1700): Isaac Newton's personal scale
Temperature in Different Industries
HVAC and Home Comfort:
| Setting | Fahrenheit | Celsius | Notes |
|---|---|---|---|
| Winter heating | 68-72°F | 20-22°C | Recommended |
| Summer cooling | 72-76°F | 22-24°C | Energy efficient |
| Sleeping | 60-67°F | 15-19°C | Optimal for sleep |
| Elderly/infants | 70-75°F | 21-24°C | Warmer needed |
Refrigeration and Food Safety:
| Zone | Fahrenheit | Celsius | Purpose |
|---|---|---|---|
| Freezer | 0°F or below | -18°C or below | Long-term storage |
| Refrigerator | 35-38°F | 2-3°C | Short-term storage |
| Danger zone | 40-140°F | 4-60°C | Bacteria multiply |
| Hot holding | 140°F+ | 60°C+ | Keep food safe |
Beverage Service Temperatures:
| Beverage | Fahrenheit | Celsius |
|---|---|---|
| Champagne | 40-45°F | 4-7°C |
| White wine | 45-50°F | 7-10°C |
| Red wine | 55-65°F | 13-18°C |
| Lager beer | 40-45°F | 4-7°C |
| Ale/stout | 50-55°F | 10-13°C |
| Hot coffee | 155-175°F | 68-80°C |
| Hot tea | 180-200°F | 82-93°C |
Global Temperature Standards
Countries Using Fahrenheit:
- United States (for weather, cooking, HVAC)
- Bahamas
- Belize
- Cayman Islands
- Liberia
- Palau
Countries Using Celsius:
- All of Europe
- All of Asia
- All of Africa
- All of South America
- Canada (officially, though some Fahrenheit persists)
- Australia
- United Kingdom (officially metric)
Mixed Usage:
- Canada: Officially Celsius, but ovens often in Fahrenheit, swimming pools in Fahrenheit, some people use Fahrenheit for body temperature
- UK: Officially Celsius, but older generations may still think in Fahrenheit
- Science worldwide: Always Celsius or Kelvin, never Fahrenheit
Historical US Metrication Attempts:
- 1975: Metric Conversion Act (voluntary)
- 1988: Omnibus Trade Act (metric for federal agencies)
- Both largely failed for everyday temperature use
- Scientific, medical, and military use metric/Celsius
Pro Tips
- 💡Memorize key reference points: 0°C=32°F (freezing), 20°C=68°F (room temp), 37°C=98.6°F (body temp), 100°C=212°F (boiling).
- 💡Quick F to C: subtract 30, divide by 2. Quick C to F: double it, add 30.
- 💡Every 5°C equals exactly 9°F—useful for adjusting from known temperatures.
- 💡-40° is the same in both Fahrenheit and Celsius—a fun fact to remember!
- 💡For cooking, 350°F = 175°C is the most common baking temperature worldwide.
- 💡A fever starts at 100.4°F (38°C)—below that is considered normal variation.
- 💡Refrigerator should be 35-38°F (2-3°C); freezer at 0°F (-18°C) or below.
- 💡Room temperature for comfort is typically 68-72°F (20-22°C).
- 💡When traveling to metric countries, 20°C is pleasant, 30°C is hot, 10°C needs a jacket.
- 💡For European recipes, subtract 25-50°F from US oven temperatures or use this converter.
- 💡Wine serving temps: white 45-50°F (7-10°C), red 55-65°F (13-18°C).
- 💡Sleep quality improves at 60-67°F (15-19°C)—cooler than daytime comfort.
Frequently Asked Questions
100°F equals 37.78°C. This is slightly above normal human body temperature (98.6°F/37°C) and would indicate a mild fever. To calculate: (100-32) × 5/9 = 68 × 0.556 = 37.78°C.
