Asthma Action Plan Calculator
Zone-based action plan from peak flow and symptoms.
About this calculator
This calculator builds two independent pieces of a NAEPP EPR-3-style asthma action plan: a traffic-light peak-flow zone and a simplified control assessment. The zone compares today's peak expiratory flow (PEF) to a personal-best PEF measured during a well-controlled period -- green at 80% or more of personal best, yellow at 50-79%, red below 50% -- and depends only on those two PEF numbers; the symptom inputs (daytime symptoms, night awakenings, rescue inhaler use, activity limitation) have zero effect on which zone is shown, since zone is a pure PEF-ratio calculation. Personal-best PEF has an outsized effect on the zone shown for a given current PEF reading, because the whole zone system is a ratio against it -- an inaccurate or outdated personal-best number, common when it hasn't been re-established after a period of improved control, will misclassify the zone even with an accurate current reading. The control score is a separate, simplified composite modeled loosely on the validated Asthma Control Test (ACT) -- it scores daytime symptoms, night awakenings, rescue inhaler use, activity limitation, and PEF percentage on a 1-5 scale each and sums to a 5-25 total, using ACT's real cut points (20+ well controlled, 16-19 not well controlled, 15 or below very poorly controlled) -- but it substitutes a PEF-based item for one of ACT's five self-report questions, so it approximates rather than reproduces the validated instrument.
More daytime symptoms, more night awakenings, more rescue inhaler use, or more activity limitation each independently lower the control score. The resulting action level is a coarse 3-tier category -- maintain current therapy, discuss stepping up, or step up significantly with urgent evaluation -- not a specific NAEPP step number: this calculator has no input for the patient's current controller-therapy step, so it cannot say which of the real 6 NAEPP steps to move to, and a "well controlled" result means keep the current regimen, not drop down to rescue-only treatment. None of this should be used to adjust medication without a clinician's involvement, particularly in the red zone, which is always a signal for immediate rescue treatment and urgent medical evaluation.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
Current Zone (0=Green, 1=Yellow, 2=Red)
0
Figures current as of 2007. Source: National Asthma Education and Prevention Program (NAEPP). Expert Panel Report 3 (EPR-3): Guidelines for the Diagnosis and Management of Asthma. National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health. 2007.
How to Use This Calculator
- Enter your personal best PEF (L/min) established during a well period.
- Enter today's current PEF (L/min) and rate daytime symptom days/week, night awakenings/week, and rescue inhaler days/week.
- The calculator determines your zone: Green (>=80% personal best), Yellow (50-79%), or Red (<50%).
- Review zone-specific action steps and medication guidance based on your current zone.
- Track daily PEF readings over time to identify worsening trends before a full exacerbation.
How the result changes with Personal Best PEF (L/min)
| Personal Best PEF (L/min) | Current Zone (0=Green, 1=Yellow, 2=Red) |
|---|---|
| 250 | 0 |
| 375 | 0 |
| 750 | 1 |
| 900 | 2 |
What each input means
- Personal Best PEF (L/min)
- Highest peak flow achieved when asthma is well controlled.
- Current PEF (L/min)
- Today's measured peak expiratory flow.
- Daytime Symptom Days/Week
- Number of days per week with daytime asthma symptoms.
- Night Awakenings/Week
- Number of nights per week woken by asthma symptoms.
- Rescue Inhaler Days/Week
- Days per week rescue inhaler is needed (not counting pre-exercise use).
- Activity Limitation (0-5)
- 0 = No limitation, 5 = Severe limitation of daily activities.
What each result means
- Current Zone (0=Green, 1=Yellow, 2=Red)
- 0 = Green (well controlled), 1 = Yellow (caution), 2 = Red (medical alert).
- % of Personal Best
- Current PEF as percentage of personal best.
- Green Zone Min PEF (L/min)
- PEF values ≥ this level (80% personal best) = green zone.
- Yellow Zone Min PEF (L/min)
- PEF values ≥ this level (50% personal best) but below green = yellow zone.
- Control Score (5-25)
- Composite asthma control score. ≥20 = well controlled, 16-19 = not well, ≤15 = very poor.
- Control Level (0=Well, 1=Not Well, 2=Poor)
- 0 = Well controlled, 1 = Not well controlled, 2 = Very poorly controlled.
- Action Level (0-2)
- 0 = Well controlled — maintain current controller therapy (this is not a recommendation to reduce treatment). 1 = Not well controlled — discuss stepping up therapy with a provider. 2 = Very poorly controlled — significant step-up and urgent evaluation needed. This calculator has no input for the patient's current NAEPP step, so it cannot recommend a specific step number.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersPersonal Best PEF (L/min) = 500, Current PEF (L/min) = 420, Daytime Symptom Days/Week = 2, Night Awakenings/Week = 1 = 6 input(s) provided
- Calculate Current Zone0 = 0
- Calculate % of Personal Best% of Personal Best = (currentPEF / personalBest) * 10084 = 84
- Calculate Green Zone Min PEFGreen Zone Min PEF = round(personalBest * 0.80)400 = 400
Figures and sources
- NAEPP EPR-3 asthma peak-flow zones and control guidelines (2007) — National Asthma Education and Prevention Program (NAEPP). Expert Panel Report 3 (EPR-3): Guidelines for the Diagnosis and Management of Asthma. National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health. 2007.
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why don't symptom days or rescue inhaler use change the peak-flow zone?
The green/yellow/red zone is calculated purely from today's PEF as a percentage of personal-best PEF -- it does not incorporate symptom frequency, night awakenings, rescue inhaler use, or activity limitation at all. Those factors instead feed the separate control score below the zone, so a patient can show a green-zone PEF reading while still scoring poorly on control if symptoms are frequent, and vice versa.
Why does personal-best PEF matter so much for the zone result?
Because the entire zone system is a ratio against it, an outdated or inaccurate personal-best figure directly misclassifies the zone even when today's PEF reading itself is measured correctly. Personal best should be re-established periodically during a period of good control -- typically over 2-3 weeks of monitoring -- rather than used indefinitely from an old measurement, since lung function and personal best can genuinely improve or decline over time.
Is the control score the same as the validated Asthma Control Test (ACT)?
No -- it borrows ACT's scoring structure and cut points (20+ well controlled, 16-19 not well controlled, 15 or below very poorly controlled) but substitutes a peak-flow-based item for one of the five self-report questions on the real ACT, so it approximates rather than reproduces the validated instrument. Treat it as a directional screening estimate, not an ACT score a clinician would record in a chart.
What should happen in the red zone regardless of the control score?
A red-zone PEF reading (below 50% of personal best) is a medical alert by itself, independent of the symptom-based control score -- it calls for immediate rescue inhaler use and urgent medical evaluation per NAEPP guidance, even if recent symptom days looked mild. The zone and control score are complementary but not interchangeable: a good recent control score does not offset a red-zone reading taken right now.
Does an action level of 0 mean I should stop or reduce my controller medication?
No -- action level 0 means well controlled on whatever therapy the patient is currently taking, and the correct response is to maintain that current controller regimen, not step down to rescue-inhaler-only treatment. This calculator has no input for the patient's actual current NAEPP step, so it never recommends a specific step number in either direction; any change to controller therapy, up or down, should go through a prescribing clinician.
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