Jonah, best 450, today 400
450 L/min best, 400 today
About 89 percent of your best. Still follow your own plan if you feel tight.
Peak Flow Percent of Best
Shows today's peak flow as a percent of your own personal best. Asthma action-plan zones belong to your written plan, not to a website. We will not colour-code red, amber or green for you.
Your details
Enter the figures you actually have, in the units on the form.
What is this calculator?
Shows today's peak flow as a percent of your own personal best. Asthma action-plan zones belong to your written plan, not to a website. We will not colour-code red, amber or green for you.
How it works
- Enter the personal best your clinic recorded.
- Enter today's best blow.
- Read the percent, then follow your own written asthma plan or call for help.
Common questions
What is the asthma peak flow zone calculator?
A percent of your best. The title says zone, but we do not assign traffic-light zones.
Why not show green, amber and red?
Those cut-offs sit on your personal action plan. Copying a generic 80/50 split would be a fake protocol.
I cannot finish a sentence.
That is urgent. Follow your red-box plan or call 999. Do not calculate first.
Example scenarios
Ayesha, best 380, today 240
380 best, 240 today
About 63 percent of your best. Use your written plan or urgent care, not this percent alone.
Neil, best 520, today 510
520 best, 510 today
About 98 percent of your best. A calm day on the meter is not a diagnosis of control.
Understanding your results
Percent is a comparison with yourself. Rescue inhalers, steroids and A&E decisions stay on your plan and with clinicians.
About this result
Guidance only. Calculations run in your browser. Numbers are estimates, not a diagnosis.
How we calculate
Today ÷ personal best × 100.
Sources
Limitations
- Not an official zone chart.
- Technique changes the number.
- Not a diagnosis of an asthma attack.
When to seek help
Speak to a GP or call NHS 111 if you are worried. Call 999 in an emergency.
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