Celsius to Fahrenheit Converter
Convert temperatures between Celsius (°C), Fahrenheit (°F), and Kelvin (K) instantly. Free UK temperature converter with weather context and reference guides.
Temperature Converter
20°C = 68°F = 293.15K
Room temperature - comfortable indoors
Quick Reference
Conversion Formulas
Key Reference Points
| Description | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20-22 | 68-72 | 293-295 |
| Body temperature | 37 | 98.6 | 310.15 |
| Fever (NHS) | 38+ | 100.4+ | 311.15+ |
| Water boils | 100 | 212 | 373.15 |
UK Weather Temperature Guide
Understanding temperature in the UK context helps you know what to expect from the weather and what to wear.
| Temperature | Description | What to Wear | |
|---|---|---|---|
| Below 0°C (32°F) | Freezing - risk of ice and snow | Heavy coat, hat, gloves, layers | |
| 0-5°C (32-41°F) | Very cold - typical UK winter | Winter coat, warm layers | |
| 5-10°C (41-50°F) | Cold - autumn/spring mornings | Warm jacket, jumper | |
| 10-15°C (50-59°F) | Cool - mild UK weather | Light jacket or cardigan | |
| 15-20°C (59-68°F) | Mild - pleasant spring/autumn | Light layers, long sleeves | |
| 20-25°C (68-77°F) | Warm - nice UK summer day | T-shirt, light clothing | |
| 25-30°C (77-86°F) | Hot - UK heatwave territory | Shorts, loose clothing, sunscreen | |
| Above 30°C (86°F) | Very hot - unusual for UK | Stay cool, stay hydrated |
Average UK Temperatures by Season
Winter (Dec-Feb)
Spring (Mar-May)
Summer (Jun-Aug)
Autumn (Sep-Nov)
UK Cooking Temperature Guide
British recipes and ovens use Celsius, but older cookbooks and some American recipes use Fahrenheit. Here's a conversion guide for common cooking temperatures.
Oven Temperature Conversions
| Gas Mark | Celsius | Fahrenheit | Description |
|---|---|---|---|
| 1/4 | 110°C | 225°F | Very cool - meringues, drying |
| 1 | 140°C | 275°F | Cool - slow cooking |
| 3 | 160°C | 325°F | Moderate - cakes, biscuits |
| 4 | 180°C | 350°F | Moderate - most baking |
| 5 | 190°C | 375°F | Moderately hot |
| 6 | 200°C | 400°F | Hot - roasting, pastry |
| 7 | 220°C | 425°F | Hot - bread, pizza |
| 8 | 230°C | 450°F | Very hot - pizza, bread crusts |
| 9 | 240°C | 475°F | Very hot - maximum heat |
Food Safety Temperatures (FSA UK)
Poultry
Beef (medium)
Pork
Reheated food
Body Temperature Guide (NHS)
Understanding body temperature is important for health monitoring, especially for fever detection.
| Condition | Celsius | Fahrenheit | NHS Guidance |
|---|---|---|---|
| Low (hypothermia risk) | Below 35°C | Below 95°F | Seek medical attention |
| Normal range | 36.1-37.2°C | 97-99°F | Healthy temperature |
| Average normal | 37°C | 98.6°F | Standard body temp |
| Elevated | 37.3-37.9°C | 99.1-100.2°F | Slightly raised, monitor |
| Fever | 38°C+ | 100.4°F+ | High temperature, rest |
| High fever | 39.4°C+ | 103°F+ | Contact NHS 111 |
| Dangerous | 40°C+ | 104°F+ | Seek urgent medical care |
Understanding Temperature Scales
Celsius (Centigrade)
The Celsius scale was developed by Swedish astronomer Anders Celsius in 1742. It's based on the freezing point (0°C) and boiling point (100°C) of water at sea level. The UK, along with most of the world, uses Celsius as the primary temperature scale.
Fahrenheit
The Fahrenheit scale was created by German physicist Daniel Gabriel Fahrenheit in 1724. It sets water's freezing point at 32°F and boiling point at 212°F. Today, it's primarily used in the United States, with limited usage in the UK by older generations.
Kelvin
The Kelvin scale is the SI unit for temperature, used in science and engineering. It starts at absolute zero (0K = -273.15°C), the theoretical lowest possible temperature where all molecular motion stops. Unlike Celsius and Fahrenheit, Kelvin doesn't use degrees - it's simply "kelvin" or "K".
Frequently Asked Questions
To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 (or 1.8) and add 32. The formula is: °F = (°C × 9/5) + 32. For example, 20°C = (20 × 1.8) + 32 = 68°F. For a quick estimate, double the Celsius and add 30.
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit temperature, then multiply by 5/9. The formula is: °C = (°F - 32) × 5/9. For example, 68°F = (68 - 32) × 5/9 = 36 × 0.556 = 20°C.
The UK officially uses Celsius for all temperature measurements, including weather forecasts (Met Office), medical purposes (NHS), and cooking. However, some older people still think in Fahrenheit, and certain newspapers report temperatures in both scales during heatwaves for context.
Normal human body temperature is approximately 37°C (98.6°F). However, the normal range varies between 36.1°C to 37.2°C (97°F to 99°F) depending on the person, time of day, and measurement method. The NHS defines a fever as 38°C (100.4°F) or higher.
Celsius and Fahrenheit are equal at exactly -40 degrees. So -40°C = -40°F. This is the only point where both scales meet. This can be proven mathematically by solving the conversion formula where °F = °C.
0 degrees Celsius equals 32 degrees Fahrenheit. This is the freezing point of water at standard atmospheric pressure (sea level). It's one of the key reference points in temperature conversion - water freezes at 0°C/32°F and boils at 100°C/212°F.
Room temperature is typically defined as 20-22°C (68-72°F) in the UK. For energy efficiency, the recommended temperature for living rooms is 18-21°C, while bedrooms should be slightly cooler at 16-19°C for optimal sleep quality.
Kelvin is the SI unit for temperature used in science. It starts at absolute zero (-273.15°C or -459.67°F) where all molecular motion theoretically stops. To convert Celsius to Kelvin, add 273.15. Unlike Celsius and Fahrenheit, Kelvin doesn't use the degree symbol - temperatures are expressed as "K" not "°K".
Related Calculators
Last updated: February 2026 | NHS and Met Office data current as of 2024
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Understanding Your Results
Our Celsius To Fahrenheit Converter provides:
- Instant calculations - Results appear immediately
- Accurate formulas - Based on official UK standards
- Clear explanations - Understand how results are derived
- 2025/26 updated - Using current rates and regulations
Common Questions
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Did You Know? Temperature Scales in Everyday UK Life
Despite the UK officially using Celsius, you will encounter Fahrenheit in several everyday situations. Many older home thermostats and ovens still display Fahrenheit, with a common oven setting of 350 degrees Fahrenheit equalling approximately 177 degrees Celsius or Gas Mark 4. The BBC weather forecast has used Celsius since the 1960s, but some UK newspapers still include Fahrenheit conversions during summer heatwaves, partly because a headline reading 100 degrees Fahrenheit sounds more dramatic than 38 degrees Celsius. For health purposes, normal body temperature is 37 degrees Celsius or 98.6 degrees Fahrenheit, and the NHS advises seeking medical attention for adults with a temperature above 38 degrees Celsius, which is 100.4 degrees Fahrenheit. Swimming pool temperatures in the UK are typically maintained between 26 and 28 degrees Celsius, equivalent to 79 to 82 degrees Fahrenheit. The quick mental approximation for converting Celsius to Fahrenheit is to double the Celsius figure and add 30, which gives a rough estimate accurate enough for most everyday purposes.
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Read the Guide →Understanding Celsius and Fahrenheit in the UK
The United Kingdom officially uses the Celsius (°C) scale for weather, cooking, and scientific purposes. However, many older UK residents still think in Fahrenheit (°F), and US visitors often need to convert temperatures. Our free converter makes this instant.
The Conversion Formula
To convert Celsius to Fahrenheit: °F = (°C × 9/5) + 32
To convert Fahrenheit to Celsius: °C = (°F − 32) × 5/9
Common UK Temperature Reference Points
- 0°C (32°F) — Water freezes; typical UK winter low
- 15°C (59°F) — Mild UK spring/autumn day
- 20°C (68°F) — Comfortable room temperature
- 25°C (77°F) — Warm UK summer day
- 37°C (98.6°F) — Average human body temperature
- 100°C (212°F) — Water boils at sea level
- 180°C (356°F) — Typical oven temperature for baking (Gas Mark 4)
UK Oven Temperatures in Celsius and Fahrenheit
UK recipes increasingly use Celsius, but older British cookbooks often list Fahrenheit or Gas Mark. Here are the most common equivalents:
- 160°C / 325°F / Gas 3 — Slow/moderate oven (casseroles, cheesecake)
- 180°C / 350°F / Gas 4 — Moderate oven (cakes, sponges)
- 200°C / 400°F / Gas 6 — Hot oven (roast potatoes, pastry)
- 220°C / 425°F / Gas 7 — Very hot oven (pizza, crusty bread)