Asthma UK community forum

Variable readings on different peak flow meters?

How accurate are peak flow meters and would you expect the same reading whichever meter you used?

The reason I ask is because I've always got a slightly lower reading on my normal GP's meter than my own (but I put this down to stress etc.) but I've seen a different GP a couple of times and I get a much higher (at least 40 more) reading on his meter so my peak flow diary looks 'wrong'.

Is it normal to get different readings on different meters and if so, would the GPs know this and how do I compensate for it (it's a problem because my lower reading on my normal GP's meter can take me below the level at which there is concern whist the other GP's meter says all is fine - how do I know which is accurate and if I should worry or not?)

4 Replies

Hello Ratty,

First check you are both using the same makes and same scales on the peak flow meter. The scale changed to EU a couple of years ago which is a yellow scale.

The old one is black. If you are using a black scale and your GP has an up to date yellow scale then the readings will be lower but are OK as the scale / measurements have changed and read lower up to a certain point.

Also the same meters can vary, depending on age too! The mechanism can get worn.

Perhaps take your meter with you when you go and test them both.

Hope this helps a little.



Just to add to Kate's post, different meters of the same manufacturer and model can also give slightly different readings.

The technical specifications for the popular Clement Clarke Mini Wright peak flow meter lists an accuracy of +/-10% (plus or minus ten percent). So a true peak flow rate of, for example, 400 L/min can produce a reading between 360 - 440 L/min and stay within the specifications. But taking your own meter along to compare readings as Kate suggests is a good idea.


A bump for Howie!


I getting bumped around a lot today.

I can take it :)


You may also like...