Free clinical calculators
Respiratory Calculators & Clinical Tools
Use free pulmonary and respiratory therapy calculators for ABG and VBG interpretation, acid-base disorders, oxygenation, ARDS, mechanical ventilation, hemodynamics, and clinical practice.
Predicted Postoperative FEV₁ & DLCO Calculator
Estimate predicted postoperative FEV₁ and DLCO with functional segment counting for lobectomy or quantitative perfusion for pneumonectomy.
Open calculatorPerioperativeARISCAT Calculator
Calculate the original seven-variable ARISCAT score for postoperative pulmonary-complication risk stratification.
Open calculatorPediatric airwayPediatric ETT Size & Depth Calculator
Calculate cuffed and uncuffed pediatric ETT sizes, oral lip-depth estimates, backups, and weight-based SGA sizes.
Open calculatorPediatric referencePediatric Vital Signs by Age
Look up source-linked pediatric heart-rate and respiratory-rate reference centiles by exact age, including months, with a distinct term-newborn pathway.
Open calculatorNeonatal airwayNeonatal ETT Size & Depth Calculator
Estimate an uncuffed neonatal ETT size and starting oral upper-gum depth from current weight and corrected gestational age.
Open calculatorCOPDBODE Index Calculator for COPD
Calculate the original 0–10 BODE score from BMI, post-bronchodilator FEV1 percent predicted, mMRC dyspnea, and six-minute walk distance.
Open calculatorPulmonary functionPFT Calculator & Spirometry Interpretation
Calculate race-neutral GLI Global predicted values, lower limits of normal, percent predicted, and z-scores for FEV1, FVC, and FEV1/FVC.
Open calculatorPulmonologyPack-Year & Lung Cancer Screening Calculator
Calculate cigarette pack-years across multiple smoking periods and compare USPSTF, ACS, and Medicare LDCT criteria.
Open calculatorPleural diseaseLight’s Criteria Calculator
Classify pleural fluid as exudative or transudative using all three criteria and review contextual pseudoexudate gradients.
Open calculatorLung nodulesFleischner Pulmonary Nodule Guidelines
Review applicability-first follow-up pathways for incidental solid, ground-glass, part-solid, single, and multiple nodules.
Open calculatorLung nodulesBrock Pulmonary Nodule Risk Calculator
Estimate pulmonary nodule malignancy probability with the full PanCan model and review the BTS 10% PET-CT threshold.
Open calculatorAsthmaAsthma Action Plan Builder
Turn clinician-supplied green, yellow, and red zone instructions into a clean printable asthma action plan.
Open calculatorAsthmaAsthma Peak Flow Zone Calculator
Calculate exact green, yellow, and red asthma peak-flow ranges from an established personal best.
Open calculatorAsthmaAsthma Control Assessment
Classify recent asthma symptom control and review future exacerbation risk factors separately using current guidance.
Open calculatorNBRC practiceFree NBRC CSE Practice – SimGenius
Practice 20 free respiratory therapy clinical simulations for NBRC CSE Information Gathering, Decision Making, and corrective replay.
Open calculatorAcid-baseWinter’s Formula Calculator
Calculate expected PaCO₂ in metabolic acidosis and identify appropriate compensation or a possible mixed respiratory disorder.
Open calculatorPopularABG Analyzer
Interpret pH, PaCO₂, HCO₃⁻, and PaO₂ with acid-base, compensation, and oxygenation guidance.
Open calculatorOxygenationP/F Ratio Calculator
Calculate the PaO₂/FiO₂ ratio and oxygenation index to assess the severity of impaired oxygenation.
Open calculatorVentilationARDSNet Assistant
Work through lung-protective ventilation, predicted body weight, tidal volume, PEEP, and FiO₂ guidance.
Open calculatorAcid-baseVBG Analyzer
Analyze venous blood gas values and recognize respiratory, metabolic, and mixed acid-base patterns.
Open calculatorHFNCROX Index Calculator
Calculate the ROX Index from SpO₂, FiO₂, and respiratory rate during high-flow nasal cannula support.
Open calculator57 free tools
Calculators, analyzers, checklists, and practice experiences in one searchable hub.
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Plain-language explanations connect each result to the underlying respiratory physiology.
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Built for education and bedside support—not as a substitute for clinical judgment.
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Search by tool, formula, abbreviation, or clinical topic—for example ABG, ECMO, anion gap, oxygen, or PaCO₂.
57 tools available.
Anesthesia & Preoperative Respiratory Assessment
Use validated respiratory risk stratification as one part of preoperative planning, with clear boundaries around individualized decisions.
Predicted Postoperative FEV₁ & DLCO Calculator
Estimate postoperative lung-function reserve with functional segment counting for lobectomy or perfusion data for pneumonectomy.
ARISCAT Calculator
Calculate the original seven-variable ARISCAT score and review every point assignment and interpretation limitation.
Pulmonology, COPD, Pulmonary Function, Lung Nodules & Pleural Disease
Assess COPD across multiple domains, interpret spirometry with GLI Global z-scores, review pulmonary nodule pathways, quantify smoking exposure, evaluate pleural-fluid physiology, and compare lung cancer screening criteria.
BODE Index Calculator for COPD
Calculate the original multidimensional BODE score with automatic BMI, post-BD FEV1, mMRC dyspnea, and measured six-minute walk distance.
PFT Calculator & Spirometry Interpretation
Calculate race-neutral GLI Global predicted values, LLN, percent predicted, and z-scores, then classify common spirometric patterns.
Pack-Year & LDCT Eligibility Calculator
Total changing cigarette-smoking patterns and compare USPSTF, American Cancer Society, and CMS Medicare criteria.
Light’s Criteria Calculator
Apply all three Light’s criteria and calculate serum–pleural protein and albumin gradients for possible pseudoexudates.
Fleischner Pulmonary Nodule Guidelines
Apply the 2017 incidental pulmonary nodule recommendations with age, screening, cancer, and immune-status exclusions checked first.
Brock Pulmonary Nodule Risk Calculator
Calculate malignancy probability with the full Brock/PanCan model and place the result in the BTS pulmonary nodule pathway.
Pediatric & Neonatal Tools
Quick age-based vital-sign references and pediatric or neonatal airway preparation tools, with population-specific limits and source context made explicit.
Pediatric Vital Signs by Age
Look up pediatric heart-rate and respiratory-rate reference centiles by exact age in days, months, or years, with a distinct term-newborn pathway.
Pediatric ETT Size & Depth Calculator
Calculate pediatric ETT size and oral depth estimates with airway alternatives and clinical context.
Neonatal ETT Size & Depth Calculator
Estimate neonatal ETT size and starting oral depth from weight and corrected gestational age.
Asthma Tools & Calculators
Assess control and future risk, calculate personal-best peak-flow zones, and create a clinician-guided printable action plan.
Asthma Control Assessment
Review four-week symptom control, SABA use, lung function, treatment factors, and future exacerbation risk.
Asthma Peak Flow Zone Calculator
Calculate personalized green, yellow, and red peak-flow zones and classify an optional current reading.
Asthma Action Plan Builder
Organize clinician-supplied daily, worsening-asthma, and emergency instructions into a printable plan.
ABG, VBG & Acid-Base Calculators
Analyze blood gases, evaluate compensation, and work through metabolic and respiratory acid-base disorders.
ABG Analyzer
Interpret arterial pH, PaCO₂, HCO₃⁻, and PaO₂ with compensation and oxygenation guidance.
VBG Analyzer
Analyze venous blood gas values and recognize common acid-base patterns.
Winter’s Formula Calculator
Estimate expected PaCO₂ in metabolic acidosis and evaluate respiratory compensation.
Anion Gap Calculator
Calculate the anion gap and albumin-corrected anion gap during metabolic acidosis evaluation.
Delta Gap Calculator
Compare the rise in anion gap with the fall in bicarbonate to screen for mixed metabolic disorders.
Respiratory Compensation Calculator
Compare measured HCO₃⁻ with expected compensation in respiratory acidosis or alkalosis.
ABGenius Practice
Practice arterial blood gas interpretation with clinical-style cases and immediate explanations.
VBGenius Practice
Practice venous blood gas interpretation and acid-base pattern recognition.
Cord Gas Analyzer
Interpret umbilical arterial and venous cord gases with acidemia and sample-reliability context.
Capillary Blood Gas Analyzer
Interpret neonatal and pediatric capillary blood gases with appropriate PO₂ limitations.
Neonatal & Pediatric VBG Analyzer
Interpret neonatal and pediatric VBG values with age-aware teaching and venous PO₂ guardrails.
Oxygenation, ARDS & Pulmonary Calculators
Assess hypoxemia, ARDS severity, HFNC response, pulmonary embolism risk, and escalation considerations.
Oxygen Delivery Devices & FiO₂ Guide
Compare adult oxygen devices, typical flow ranges, estimated or controlled FiO₂, setup checks, and safety warnings.
Oxygen Saturation Target Navigator
Match adult, COPD, ARDSNet, postarrest, pediatric, and neonatal contexts to source-labeled SpO₂ target guidance.
P/F Ratio & Oxygenation Index
Calculate the PaO₂/FiO₂ ratio and oxygenation index for oxygenation severity assessment.
A–a Gradient Calculator
Calculate the alveolar–arterial oxygen gradient when evaluating the mechanism of hypoxemia.
ROX Index Calculator
Calculate the ROX Index during high-flow nasal cannula support using SpO₂, FiO₂, and respiratory rate.
Berlin ARDS Criteria
Apply the Berlin ARDS criteria and classify oxygenation severity using the P/F ratio and support level.
Murray Lung Injury Score
Calculate the Murray Lung Injury Score from imaging, P/F ratio, PEEP, and compliance inputs.
PE Rule-Out Toolkit
Use Wells criteria and the PERC rule as part of pulmonary embolism risk assessment.
Pre/Post-Ductal Analyzer
Compare preductal and postductal oxygenation values in neonatal shunt evaluation.
Oxygen Tank Duration Calculator
Estimate remaining oxygen-cylinder time from pressure, flow, tank factor, and reserve pressure.
VV ECMO Referral Criteria
Review severe respiratory-failure findings that may support early VV ECMO center consultation.
ECMO Contraindications Checklist
Screen major and relative concerns before an ECMO referral discussion.
Mechanical Ventilation Calculators
Connect tidal volume, predicted body weight, minute ventilation, dead space, PaCO₂, and weaning calculations.
Pediatric ETT Size & Depth Calculator
Calculate cuffed and uncuffed ETT sizes, oral depth methods, adjacent backups, and device-specific SGA sizes for ages 1–18.
Neonatal ETT Size & Depth Calculator
Estimate neonatal uncuffed ETT size, oral insertion-depth methods, backup sizes, and conditional SGA guidance.
ARDSNet Assistant
Work through predicted body weight, lung-protective tidal volume, PEEP, and FiO₂ guidance.
Static Compliance Calculator
Calculate static respiratory system compliance and driving pressure using tidal volume, plateau pressure, and total PEEP.
Suction Catheter Size Calculator
Match standard suction catheter French sizes to ETT or tracheostomy internal diameter and inspect diameter and lumen-area ratios.
RSI Dosage Calculator
Calculate adult rapid sequence intubation doses for common induction agents and paralytics.
Minute & Alveolar Ventilation
Calculate minute ventilation and alveolar ventilation from tidal volume, rate, and dead space.
Dead Space Calculator
Estimate physiologic dead-space fraction and volume using PaCO₂, exhaled CO₂, and tidal volume.
Desired Minute Ventilation
Estimate a desired minute ventilation from the current and target PaCO₂.
Desired PaCO₂ Triangle
Calculate one missing value from desired PaCO₂, measured bicarbonate, and normal bicarbonate.
Ideal Body Weight Calculator
Calculate predicted or ideal body weight for lung-protective tidal-volume selection.
RSBI Calculator
Calculate the rapid shallow breathing index during ventilator-weaning assessment.
Hemodynamics & Oxygen Delivery Calculators
Relate perfusion, oxygen delivery, cardiac output, mixed venous saturation, and shock physiology.
ECMO Oxygen Content & Transfer Calculator
Calculate systemic oxygen content and delivery, and estimate oxygen transfer across the ECMO membrane lung from paired circuit blood gases.
SvO₂ Calculator
Estimate arterial oxygen content, oxygen delivery, and venous saturation from a simplified Fick relationship.
Fick Cardiac Output Calculator
Estimate cardiac output from oxygen consumption and arterial–venous oxygen content difference.
MAP & Shock Index Calculator
Calculate mean arterial pressure, shock index, and pulse pressure from bedside vital signs.
Respiratory Therapy Practice Tools
Build clinical sequencing and pattern recognition through NBRC simulations, oxygenation, chest X-ray, and respiratory pharmacology practice.
Free NBRC CSE Practice – SimGenius
Work through 20 free, source-cited respiratory simulations with Information Gathering, Decision Making, and corrective replay.
OxyGenius Practice
Practice PaO₂ classification, P/F ratios, oxygenation severity, and Berlin ARDS criteria.
Chest X-Ray Practice
Practice a systematic chest X-ray review with interactive pulmonary imaging cases.
Respiratory Pharmacology Practice
Review bronchodilators, inhaled medications, drug classes, and respiratory pharmacology concepts.
Common questions
How to choose a respiratory calculator
Start with the clinical question. Blood gas tools evaluate acid-base patterns; oxygenation tools assess gas exchange; ventilation tools focus on mechanics and CO₂ clearance.
Are PulmTools respiratory calculators free?
Yes. The calculators, analyzers, and practice tools listed on this page can be used without a paid subscription.
Which tool should I use for metabolic acidosis?
Start with the ABG or VBG Analyzer to identify the acid-base pattern. When metabolic acidosis is present, use the anion gap, delta gap, and Winter’s Formula Calculator to evaluate the disorder and expected respiratory compensation.
Which calculator assesses oxygenation severity?
The P/F Ratio and Oxygenation Index calculator assesses oxygenation severity. The A–a Gradient Calculator, ROX Index, and Berlin ARDS Criteria tools answer related but different clinical questions.
Can these tools replace clinical judgment or local protocols?
No. PulmTools provides educational calculation and decision-support resources. Results must be interpreted with the full clinical picture and verified against current institutional policies and authoritative guidance.
Clinical-use notice
PulmTools calculators and practice resources are intended for education and clinical decision support. They do not establish a diagnosis or replace examination, complete patient data, professional judgment, current guidelines, or institutional protocols. Verify calculations and recommendations before applying them to patient care.