PaO2/FiO2 (P/F) Ratio Calculator

Calculate the PaO2/FiO2 ratio, a key metric in assessing lung function, with our advanced and accessible online tool.

Full original guide (expanded)

PaO2/FiO2 (P/F) Ratio Calculator

This calculator helps healthcare professionals assess lung function by calculating the PaO2/FiO2 ratio, a crucial metric in diagnosing ARDS and other respiratory conditions.

Results

P/F Ratio N/A

Data Source and Methodology

All calculations are strictly based on the formulas and data provided by authoritative medical sources.

Reference: MDCalc - Horowitz Index

The Formula Explained

The P/F Ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)

Glossary of Terms

  • PaO2: Partial pressure of oxygen in arterial blood, measured in mmHg.
  • FiO2: Fraction of inspired oxygen, expressed as a percentage.
  • P/F Ratio: A key indicator of pulmonary function.

How It Works: A Step-by-Step Example

For example, with a PaO2 of 80 mmHg and an FiO2 of 50%, the P/F ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{80}{0.5} = 160 \)

Frequently Asked Questions (FAQ)

What is the P/F ratio used for?

The P/F ratio is used to assess the severity of respiratory failure and guide treatment decisions.

What is a normal P/F ratio?

A normal P/F ratio is typically above 300. A lower ratio indicates impaired lung function.

How do I convert FiO2 percentage to a decimal?

Divide the FiO2 percentage by 100 to convert it to a decimal.

Why is the P/F ratio important?

It provides a quick assessment of oxygenation efficiency and the severity of hypoxemia.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Formula (extracted text)
The P/F Ratio is calculated as follows: \( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn

PaO2/FiO2 (P/F) Ratio Calculator

This calculator helps healthcare professionals assess lung function by calculating the PaO2/FiO2 ratio, a crucial metric in diagnosing ARDS and other respiratory conditions.

Results

P/F Ratio N/A

Data Source and Methodology

All calculations are strictly based on the formulas and data provided by authoritative medical sources.

Reference: MDCalc - Horowitz Index

The Formula Explained

The P/F Ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)

Glossary of Terms

  • PaO2: Partial pressure of oxygen in arterial blood, measured in mmHg.
  • FiO2: Fraction of inspired oxygen, expressed as a percentage.
  • P/F Ratio: A key indicator of pulmonary function.

How It Works: A Step-by-Step Example

For example, with a PaO2 of 80 mmHg and an FiO2 of 50%, the P/F ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{80}{0.5} = 160 \)

Frequently Asked Questions (FAQ)

What is the P/F ratio used for?

The P/F ratio is used to assess the severity of respiratory failure and guide treatment decisions.

What is a normal P/F ratio?

A normal P/F ratio is typically above 300. A lower ratio indicates impaired lung function.

How do I convert FiO2 percentage to a decimal?

Divide the FiO2 percentage by 100 to convert it to a decimal.

Why is the P/F ratio important?

It provides a quick assessment of oxygenation efficiency and the severity of hypoxemia.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Formula (extracted text)
The P/F Ratio is calculated as follows: \( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn

PaO2/FiO2 (P/F) Ratio Calculator

This calculator helps healthcare professionals assess lung function by calculating the PaO2/FiO2 ratio, a crucial metric in diagnosing ARDS and other respiratory conditions.

Results

P/F Ratio N/A

Data Source and Methodology

All calculations are strictly based on the formulas and data provided by authoritative medical sources.

Reference: MDCalc - Horowitz Index

The Formula Explained

The P/F Ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)

Glossary of Terms

  • PaO2: Partial pressure of oxygen in arterial blood, measured in mmHg.
  • FiO2: Fraction of inspired oxygen, expressed as a percentage.
  • P/F Ratio: A key indicator of pulmonary function.

How It Works: A Step-by-Step Example

For example, with a PaO2 of 80 mmHg and an FiO2 of 50%, the P/F ratio is calculated as follows:

\( \text{P/F Ratio} = \frac{80}{0.5} = 160 \)

Frequently Asked Questions (FAQ)

What is the P/F ratio used for?

The P/F ratio is used to assess the severity of respiratory failure and guide treatment decisions.

What is a normal P/F ratio?

A normal P/F ratio is typically above 300. A lower ratio indicates impaired lung function.

How do I convert FiO2 percentage to a decimal?

Divide the FiO2 percentage by 100 to convert it to a decimal.

Why is the P/F ratio important?

It provides a quick assessment of oxygenation efficiency and the severity of hypoxemia.


Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
\[','\]
','
Formula (extracted text)
The P/F Ratio is calculated as follows: \( \text{P/F Ratio} = \frac{\text{PaO2}}{\text{FiO2}} \)
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn
Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft
Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog
  • 0.1.0-draft — 2026-01-19: Initial draft (review required).