GOLD Airflow Limitation Grade Interpreter

Place a post-bronchodilator FEV1 percent predicted in GOLD’s four airflow limitation grades, with the spirometric gate GOLD requires first — and the ERS/ATS objection to grading on percent predicted at all.

Last updated 8 Oct 2026

GOLD airflow limitation grade

GOLD 1 to 4 on post-bronchodilator FEV1

Post-bronchodilator FEV1, percent of predictedFEV1 after the bronchodilator, as a percentage of the predicted value — 62, not 0.62. Take it from the report rather than computing it, so that it carries the same reference set as the rest of the report. Predicted values, LLNs and z-scores are reference-set dependent — GLI 2012, GLI Global, NHANES III and ECSC disagree for the same person — so use the set your own report names.

Post-bronchodilator FEV1/FVC ratioThe same session’s post-bronchodilator ratio, as a decimal — 0.58, not 58. GOLD’s grades only apply once this is below 0.70; the grade is a subdivision of airflow limitation, not a test for it. The fixed 0.70 cut-off is itself contested, which the FEV1/FVC ratio and obstruction interpreter sets out against the ERS/ATS lower limit of normal.

GOLD 2, moderate: FEV1 at least 50 and under 80 percent of predictedExample

Post-bronchodilator FEV1 62% of predicted, FEV1/FVC 0.58

GOLD’s four grades of airflow limitation

Applied only where the post-bronchodilator FEV1/FVC is below 0.70. The inequality form is taken from BMJ Best Practice’s COPD criteria page and confirmed against GPnotebook, both citing GOLD’s 2025 report; the GOLD pocket guide’s own figure carrying these grades did not come through as text when the primary document was read, so it is not sourced to it. The cut-offs are short factual criteria quoted with attribution — GOLD’s strategy report is copyrighted and no table or figure from it is reproduced here.
Grade	Label	Post-bronchodilator FEV1
GOLD 1	Mild	at or above 80% predicted
GOLD 2	Moderate	at least 50% and under 80% predicted
GOLD 3	Severe	at least 30% and under 50% predicted
GOLD 4	Very severe	under 30% predicted

Two bodies, two severity gradings, one spirogram

The two are not translations of one another, because the conversion between percent predicted and a z-score depends on the ratio of the predicted value to the reference population’s standard deviation, and that ratio changes with age and height. The percent predicted and z-score converter does the conversion from your report’s own numbers and shows why the two cannot be mapped once and for all.
Body	What it grades on	Why
GOLD	FEV1 as a percentage of predicted, in four grades	Continuity with three decades of COPD literature and trial entry criteria
ERS / ATS 2022	The FEV1 z-score, in three grades	Percent predicted carries an age, height and sex bias; the standard says it leads to systematic misinterpretation, particularly for women, children and older adults

What the grade is for, and the currency argument underneath it

GOLD’s grades do one narrow job: they divide airflow limitation, once it has been established, into four strata on the post-bronchodilator FEV1 as a percentage of predicted. The gate comes first. GOLD’s 2025 report makes a post-bronchodilator FEV1/FVC below 0.70 mandatory to establish a diagnosis of COPD, and the grades are a subdivision of that finding rather than a test for it — which is why a very low FEV1 with a preserved ratio gets no GOLD grade at all and needs lung volumes instead.

The grade is also not a severity of illness, and GOLD’s own strategy is built around that fact: the spirometric grade and the symptom-and-exacerbation assessment are deliberately separate axes, because FEV1 correlates poorly at an individual level with breathlessness, exercise capacity, quality of life and the risk of the next exacerbation. Two patients at 45% of predicted can live very differently.

Underneath the grades is a live disagreement about the currency. GOLD grades on percent predicted. The 2022 ERS/ATS technical standard grades severity on the FEV1 z-score and “strongly discourages” percent-predicted cut-offs, on the grounds that percent predicted “does not take into account the observed age-related changes in measurement variability” and leads to “systematic misinterpretation of results, particularly for women, children and older adults”. Both gradings are in current use, they are not translations of each other, and a report can carry one or both.

Predicted values, lower limits of normal and z-scores are reference-set dependent: GLI 2012, the race-neutral GLI Global average equations, NHANES III and the older ECSC equations give different predicted values for the same person, and a result can cross a threshold purely because the laboratory changed reference set. Read this against the set printed on your own report. That matters more here than anywhere else in this category, because a GOLD grade is a percentage of a predicted value: change the reference set and the percentage changes without the patient changing, and a result near 50% or 80% can cross a grade boundary for that reason alone. This supports a clinician’s judgement rather than replacing it. A lung function pattern is interpreted with the clinical picture and the report’s own reference set, never on its own.

Frequently asked questions

What are the GOLD grades of airflow limitation?

Four strata on the post-bronchodilator FEV1 as a percentage of predicted, applied only where the post-bronchodilator FEV1/FVC is below 0.70: GOLD 1 mild at or above 80%, GOLD 2 moderate at least 50% and under 80%, GOLD 3 severe at least 30% and under 50%, and GOLD 4 very severe under 30%.

Does a GOLD grade measure how ill someone is?

No. It is a spirometric stratum. GOLD’s own strategy keeps the spirometric grade separate from the symptom and exacerbation assessment because FEV1 correlates poorly at an individual level with breathlessness, exercise capacity and exacerbation risk.

Why does the ERS/ATS standard not use these grades?

Because they are denominated in percent predicted. The 2022 standard grades severity on the FEV1 z-score and discourages percent-predicted cut-offs, since percent predicted ignores the way the spread of healthy values changes with age — which it says causes systematic misinterpretation, particularly in women, children and older adults.

What if the FEV1 is low but the ratio is above 0.70?

Then no GOLD grade applies, and that is informative rather than reassuring. A low FEV1 with a preserved ratio is a restrictive or mixed pattern, or the preserved-ratio impaired spirometry the 2022 ERS/ATS standard describes, and it needs a measured total lung capacity rather than a ratio to characterise.

Which grade does exactly 50% of predicted fall in?

GOLD 2. The published bands are inequalities — GOLD 2 is at least 50% and under 80%, GOLD 3 is at least 30% and under 50% — so each boundary belongs to the less severe grade. Sources that print the bands as “50 to 79” and “30 to 49” round those open boundaries and leave values such as 79.5% unassigned.

Related calculators

References

Global Initiative for Chronic Obstructive Lung Disease. Pocket Guide to COPD Diagnosis, Management and Prevention: 2025 Report. GOLD, 2024.
BMJ Best Practice. Chronic obstructive pulmonary disease: diagnostic criteria. London: BMJ Publishing Group, 2025.
GPnotebook. Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Oxford: GPnotebook, 2025.
Stanojevic S, Kaminsky DA, Miller MR, et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J. 2022;60(1):2101499.
Swanney MP, Ruppel G, Enright PL, et al. Using the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction. Thorax. 2008;63(12):1046–51.

Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/