parts per billion to parts per million

[sandbach99]

I have a report which quotes various chemicals in parts per billion. When I google these chemicals are normally in parts per million.

If a substance is 2.5 parts per billion what amount is it in parts per million, can't decide which way the decimal point goes|

Thanks

[rojash]

If it's 2.5 in a billion, it;s gonna be less in a million - so you need to move the point to the left. How far you move it will depend on whether your billion is an English one (1 million million) or (most likely) an American one (1000 million).

[R1Geezer]

well assuming we are using 10E9 as a billion then it's 1000 times more than a million so for parts per million divide by 1000, ie move the DP 3 places to the left so 2.5 parts per billion = 0.0025 parts per million. The Geezer is wise today

[wildwood]

So that's why there are more billionaires in USA than in UK.

[sandbach99]

Thanks for the replies

[Cheeris]

(Semi-)officially the UK uses the short-scale definition (i.e.' a thousand millions'), and has done for some time.

Informal use of the traditional long-scale version is still used but is in the minority IMO.