Start with A0 which has an area of 1 square meter.
Long:short ratio is always sqrt2.
Divide the long side by two for A1, continue for A2, A3, A4, A5, and so on.
Jez
On 5 May 2012 23:36, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> Thanks. I hadn't realized that. Ax where x is even is 3:2, Ax where x
> is odd is 4:2.8.
>
> But not having A size printing papers I've now accumulated yet another
> very interesting but useless to me piece of info. :-)
>
> Chuck Norcutt
>
>
> On 5/5/2012 12:15 PM, Frank Wijsmuller wrote:
> > Actually, because the A-x formats *double* each iteration in only one
> > direction (*not* proportionally 'enlarged'!), they serve both 2x3 and 3x4
> > sensors...
> > ....
> > A5 ~ 4x3 (210x148mm - 4:2,8)
> > A4 ~ 3x2 (297x210mm - 3:2,1)
> > A3 ~ 4x3 (420x297mm - 4:2,8)
> > A2 ~ 3x2 (594x420mm - 3:2,1)
> > ....
> >
> > That makes it a draw ;-)
> >
> > Best, Frank.
> >
> >
> > 2012/5/5 Wayne Harridge<wayne.harridge@xxxxxxxxxxxxxxxxxxx>
> >
> >> 4/3 is also a good fit for A4, A3,... paper sizes.
> >>
> >>
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