Celsius to Fahrenheit Converter

How to use this converter

1. Type in either box. Enter degrees in the Celsius field and the Fahrenheit field updates live — or type Fahrenheit and Celsius fills in. There's no Calculate button; the math runs as you type.
2. Use a preset for the common ones. The chips fill in freezing (0°C), room temperature (20°C), normal body temperature (37°C), the fever line (38°C), and boiling (100°C).
3. Read the fever band — if it's a body temperature. When your number lands in human range (roughly 90–113°F), a colored band appears: Normal, Low-grade, Fever, High fever, or Hypothermia, with a one-line "what this means." For ambient temperatures you'll see a plain-English reference note instead.
4. Copy, share, or print. Copy the conversion as text, grab a share link that reopens this exact value, or download a one-page printable °C–°F chart with the fever reference built in.

Why this converter is different from other Celsius-to-Fahrenheit pages

Most temperature converters online do exactly one thing: turn a number on one scale into a number on the other. That's fine until the number you typed is a body temperature and you actually want to know whether 38°C is a fever (it is) or whether 100°F is something to worry about (it's borderline). Here's what this tool adds:

• Both directions, in real time. Type in Celsius or Fahrenheit — no toggle, no "Convert" button, no page reload. Most pages convert one way only.
• A fever check built in. When the value is a body temperature, you get the clinical band (the fever line is 100.4°F / 38.0°C, per the CDC) and what to do — not just a number. No general converter does this.
• A printable chart, not a static PDF. The top results for this search are fixed PDF charts from decades ago. Ours generates a clean, current °C–°F chart on demand, with the fever reference included.
• Embeddable, free. Teachers, school nurses, travel bloggers, and clinic sites can drop the live converter onto their own page with one line of code. Almost no converter offers this.
• Reviewed by a physician. Most converters are anonymous widgets. This one is reviewed by Dr. David Taylor, MD, PhD, with the formula and sources shown openly.

How the conversion works (the math)

Celsius and Fahrenheit are two straight-line scales pinned to different reference points, so converting between them is a single linear formula in each direction:

°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9

The 9/5 (which equals 1.8) is the ratio of the degree sizes — a Fahrenheit degree is smaller than a Celsius degree — and the + 32 shifts the zero point, because 0°C (water freezing) sits at 32°F. The two scales cross at exactly −40°, where −40°C = −40°F. The mental-math shortcut you'll see online (“double it and add 30”) is close for everyday temperatures but drifts by several degrees at the extremes, which is why a fever calculation deserves the exact formula. Definitions of the scales and their fixed points come from NIST; the 100.4°F (38.0°C) fever threshold is the CDC's standard definition.

Worked examples

Is 38°C a fever?

Yes. 38 × 9/5 + 32 = 100.4°F, which is exactly the clinical fever threshold. A child or adult reading 38°C has a low-grade fever right at the line — rest and fluids, and watch for other symptoms. If you're tracking it over a day, an accurate digital thermometer matters more than the scale you read it in.

What's a normal temperature in Fahrenheit?

The textbook average is 37°C, which converts to 37 × 9/5 + 32 = 98.6°F. In practice "normal" is a range — roughly 97–99°F (36.1–37.2°C) — and it shifts with time of day and where you measure. A forehead thermometer reads a touch lower than an oral one, which is normal and expected.

It's 35°C outside — is that hot?

Very. 35 × 9/5 + 32 = 95°F — a hot summer day. Because 35°C is also at the edge of body-temperature range, the tool flags it; for an ambient reading you'd read it as weather, not a fever. The fever band only matters when the number is coming from a thermometer held to a person.

Celsius to Fahrenheit reference chart

The everyday range at a glance. Rows in the body-temperature zone are highlighted — that's where the fever bands apply.

Frequently asked questions

Is 100°F equal to 40°C?

No — that's a common mix-up. 100°F is about 37.8°C, just over normal body temperature and a touch below the fever line. 40°C is much hotter: 104°F, a high fever. Type either into the converter above to see it exactly.

What is normal body temperature in Celsius and Fahrenheit?

The classic average is 37°C / 98.6°F, but a healthy range runs roughly 36.1–37.2°C (97–99°F). It varies by person, time of day, and measurement site. A reading at or above 38°C (100.4°F) is the standard definition of a fever.

How do I convert Celsius to Fahrenheit without a calculator?

Multiply the Celsius number by 1.8 and add 32 for the exact answer. For a quick mental estimate, double it and add 30 — but that shortcut can be off by several degrees, so use the exact formula for anything medical.

What temperature is the same in Celsius and Fahrenheit?

Exactly −40°. At minus forty, the two scales meet: −40°C = −40°F. It's the only point where they're equal.

Can I embed this converter on my own site?

Yes — copy the snippet at the bottom of this page. The embedded version is a stripped-down converter built for classrooms, school-nurse pages, clinic sites, and travel blogs. Required attribution is included; there's no fee, signup, or tracking attached.

Related tools

• Pulse Oximeter Reading Chart — read an SpO₂ value the same way you'd read a temperature.
• Blood Pressure Log — color-coded BP tracking with a printable PDF.
• Browse all free tools by Dr. Taylor →

Dr. Taylor's thermometer recommendations

A converter tells you what 38°C means; an accurate thermometer is how you got the number in the first place. If a fever reading sent you here, these are the categories worth getting right:

• Best Digital Thermometers — the clinical baseline for oral and underarm readings.
• Best Forehead Thermometers — no-contact reads for a sleeping child or a fast recheck.
• Best Infrared Thermometers — touchless readings for the whole household when illness is going around.

Sources & methodology

• NIST — SI Units: Temperature — definitions and fixed points of the Celsius and Fahrenheit scales.
• U.S. Centers for Disease Control and Prevention — fever defined as a measured temperature of 100.4°F (38.0°C) or higher.
• Conversion cross-validated against the Google instant-answer widget and CalculatorSoup to the exact value.

The conversion is a mathematical identity and does not change; this page is reviewed annually for citation currency. About Dr. Taylor · Last reviewed June 4, 2026.

Embed this tool on your site

Free for classrooms, school-nurse pages, clinics, travel blogs, and personal sites. Required attribution is included in the snippet. No fee, no signup, no tracking attached to the embed.

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  Celsius to Fahrenheit converter by
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