Convert Celsius to Fahrenheit – Temperature Converter
This converter transforms a single temperature value in degrees Celsius (°C) into degrees Fahrenheit (°F) using the fixed mathematical relationship between the two scales. It is intended for quick calculations, educational purposes, lab notes, field measurements, and safety checks.
For measurement and safety applications, be mindful that the numerical conversion is exact for arithmetic values but real-world temperature readings may include sensor error, calibration offsets, and uncertainty. Consult calibration and traceability guidance when using converted values for compliance, health and safety, or instrumentation.
Interactive Converter
Convert between celsius and fahrenheit with precision rounding.
Quick reference table
| Celsius | Fahrenheit |
|---|---|
| 1 °C | 33.8 °F |
| 5 °C | 41 °F |
| 10 °C | 50 °F |
| 25 °C | 77 °F |
| 50 °C | 122 °F |
| 100 °C | 212 °F |
Methodology
The conversion uses the internationally recognized linear relationship between the Celsius and Fahrenheit scales. The formula F = C × 9/5 + 32 converts Celsius to Fahrenheit; the inverse is C = (F − 32) × 5/9.
When applied to measurement results, conversion is independent of the measurement instrument. However, good practice requires that the original temperature measurement be traceable to standards (for example NIST-traceable calibration) and that uncertainty be reported per ISO guidance. For occupational health thresholds and heat-stress limits, follow relevant regulatory guidance such as published OSHA recommendations.
Worked examples
0 °C → (0 × 9/5) + 32 = 32 °F
100 °C → (100 × 9/5) + 32 = 212 °F
-40 °C → (-40 × 9/5) + 32 = -40 °F (the two scales coincide at -40)
Absolute zero: -273.15 °C → (-273.15 × 9/5) + 32 = -459.67 °F
Expert Q&A
Is the conversion exact?
The mathematical conversion using F = C × 9/5 + 32 is exact for numerical values. Real-world temperature measurements include instrument error and uncertainty; converted reported values inherit that uncertainty. For metrology or regulatory work, include measurement uncertainty and calibration status per relevant standards.
How many decimal places should I use?
Choose decimal places based on the precision of your original measurement. Do not imply greater precision than your instrument provides. For many general uses, one decimal place is sufficient; for lab or engineering work, follow your instrument's specification and report uncertainty per ISO 17025 guidance.
Why does the formula use 9/5 and 32?
The factor 9/5 arises from the ratio of the size of the Fahrenheit degree to the Celsius degree; adding 32 accounts for the different zero points of the two scales. This relationship is fixed and derived from the definitions of the scales.
Are there regulatory considerations for converted temperatures?
Yes. When converted temperatures are used for safety limits, compliance, or health assessments, ensure that measurement instruments are calibrated and traceable to standards such as those published by NIST and that you follow applicable workplace or industry regulations (for example OSHA heat guidelines).
What about sensor calibration and traceability?
Calibration establishes a link between an instrument's readings and reference standards. For authoritative measurement, ensure sensors are calibrated at appropriate intervals, document traceability (for example to NIST), and include calibration uncertainty in any reported converted value.
Sources & citations
- NIST — SI Units: Temperature — https://www.nist.gov/pml/weights-and-measures/si-units-temperature
- ISO 80000-5 — Quantities and units: Thermodynamics (temperature) — https://www.iso.org/standard/54562.html
- IEEE — Sensor and instrumentation standards (examples include IEEE sensor family standards) — https://standards.ieee.org
- OSHA — Heat Exposure and Heat Illness Prevention — https://www.osha.gov/heat