# 1 / 1000 is ...

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#### Tomasz Klimkiewicz

##### Senior Member
Greetings,

I need some help from our experts for a paper I'm writing at the moment.

In English one per one hundred is percent,

one per one thousand is

a) promille
b) per mille
c) should I use a decimal fraction instead.

A prompt reply will earn my most sincere gratitude.

#### Tdol

##### Editor, UsingEnglish.com
Staff member
Either say one per thousand or use a decimal.;-)

#### Tomasz Klimkiewicz

##### Senior Member
Thanks, so much Tdol.
The magnitude I need to express is the slope (or gradient) of a tunnel under construction. In civil engineering, such changes in elevation are typically expressed in parts per thousand. In my mother tongue 'promille' is a valid expression in this context, hence my question. T.K.

#### twostep

##### Senior Member
Tomasz Klimkiewicz said:
Greetings,

I need some help from our experts for a paper I'm writing at the moment.

In English one per one hundred is percent,

one per one thousand is

a) promille
b) per mille
c) should I use a decimal fraction instead.

A prompt reply will earn my most sincere gratitude.

Promille - used for blood alcohol contents (at least in German)
.001 is linnear meassure; per milliliter (liquid),
Mil - used for thickness (6mil plastic is .006 inch think)

I would use decimal fractions especially in Europe. Can you give me some details?

#### Tomasz Klimkiewicz

##### Senior Member
twostep,

The English paper I'm working at just now is on construction of a sewerage duct using a state-of-the-art technology called microtunnelling. I won't go deeply into technical details; the point is that it's a general-purpose wastewater collector working as a gravitational flow duct, that's why it needs to have a negative gradient towards its end. That gradient, or slope, is expressed in metres per / 1000 m, meaning the difference in elevation after each kilometer of the duct (the exact number may vary over the whole length of the sewer). All in all, I gave up that 'promille' notion for the sake of clarity, and simply used m / 1000 m, which is just the same. Consulted some civil engineering manuals, and it's O.K.

Cheers! T.K.

#### twostep

##### Senior Member
Tomasz Klimkiewicz said:
twostep,