Peak flow zone today

Enter your reading to see how today compares with your best. The zone tells you which part of your action plan to follow.

Your details

Today's best of three
Your personal best

360 against a best of 460

78%

Under 80% of your best

  • 80% of your best368
  • 50% of your best230
  • Gap to your best100 L/min

This is the amber zone: your asthma is getting worse. Follow the amber part of your action plan and contact your GP or asthma nurse today. How you feel counts as much as the number: an asthma attack is an emergency even when peak flow looks normal.

Call 999 if your reliever is not helping or not lasting 4 hours, you find it hard to walk or talk because you are breathless, or you are wheezing a lot with a very tight chest. Follow your asthma action plan while you wait.

The working

360 against a best of 460

360 ÷ 460 = 78%, just under the 80% line, so today is in the amber zone: asthma is getting worse. Follow the amber part of your plan and get in touch with your GP or asthma nurse today.

The zones

Green, amber and red

Zone% of your bestWhat to do
Green80% or morekeep taking your preventer as prescribed
Amberunder 80%follow the amber part of your plan; contact your GP or nurse
Redunder 50%asthma attack steps now; call 999 if not better or worse at any point

Asthma attack

With a blue reliever inhaler

  • Sit up, and try to keep calm
  • One puff of your reliever every 30 to 60 seconds, up to 10 puffs
  • Call 999 if you feel worse at any point, or are not better after 10 puffs
  • If the ambulance has not come after 10 minutes and you are no better, repeat the puffs

This is the Asthma + Lung UK advice for a blue reliever. If you use a MART inhaler, follow your own plan.

Read with care

What this cannot tell you

  • Override how you feelSymptoms matter as much as the number.
  • Cover MART plansFollow the plan for your own inhaler.
  • Work without a bestYou need your own personal best first.

Questions

Common questions

What peak flow percentage is an asthma attack?

Most plans treat under 50% of your best as the red zone. Act on symptoms too, even if the number looks fine.

What does amber mean on an asthma plan?

Your asthma is getting worse. Follow the amber steps and contact your GP or asthma nurse.

How often should I check my peak flow?

As your nurse suggests. Many people check morning and evening when unwell or after a change in treatment.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

If breathing is hard

Call 999 if your reliever is not helping, you cannot walk or talk because of breathlessness, or you feel worse at any point. Contact your GP or asthma nurse the same day after any attack you managed at home.

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