What's your normal peak flow?

Peak flow measures how forcefully you can breathe out. Enter your details to find the predicted normal value for someone your age, sex and height — and the zones that tell you what a reading means.

Sex

Age (years)

Height

Result

Fill in your details and your predicted value will appear here.

— L/min

Predicted normal for —

0 — — —

Reading against your best

Green — all clear

80% or more of your best. Breathing is well controlled.

—

Yellow — caution

50–79%. Airways narrowing. Follow your action plan.

—

Red — medical alert

Below 50%. Use reliever and seek help now.

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Note: This predicted value is a starting reference. A patient's own personal best — the highest steady reading over a good spell — is the number the zones above should really be built on.