A free, open-access noise figure calculator for RF engineers, students, and researchers — built to simplify the Y-Factor measurement process.
Ready to measure your device's noise figure?
Open the Calculator →The Y-Factor Noise Figure Calculator is a free web-based tool that computes the noise figure of RF two-port devices — such as low-noise amplifiers (LNAs), mixers, and filters — using the Y-Factor measurement method with a spectrum analyzer and calibrated noise source.
The calculator implements the full second-stage corrected measurement procedure described in the Rohde & Schwarz application note 1MA178. This correction removes the noise contribution of the spectrum analyzer itself from the final result using the Friis cascade equation, giving a more accurate noise figure for the device under test.
Noise figure measurement is a routine task in RF engineering labs, but calculating it correctly — especially with second-stage correction — requires careful arithmetic that is easy to get wrong. Most engineers either write their own spreadsheet or rely on dedicated noise figure analyzers that cost tens of thousands of dollars.
This tool provides a free, accessible alternative for engineers who already have a spectrum analyzer and noise source, making the Y-Factor calculation fast, reliable, and available from any browser without installing software.
All calculations are based on the Y-Factor method as described in the Rohde & Schwarz application note 1MA178: The Y-Factor Technique for Noise Figure Measurements. The noise figure is derived from four spectrum analyzer power readings and the known Excess Noise Ratio (ENR) of the noise source, with automatic second-stage correction applied via the Friis noise cascade formula.
The reference temperature used is T₀ = 290 K, consistent with the IEEE standard definition of noise figure.
For questions, feedback, or bug reports, contact us at contact@noisefigurecalculator.com.