If its any easier for you, work it out as:
1000 x 1000 pixels = 85mm x 85mm (approx @ 300 dpi)
So, say you have a pano 6000 x 3000, that will give you a very good quality print approx 50 cm x 25cm (@300dpi)
If you use photoshop just open your pano then go to image size - click OFF resample image, then put resolution to 300 pixels/inch. this will resize the pano suitable for print.
then you can mess around with the size in mm/cm etc to the suitable size you require.
If you dont have photoshop you can still use the above to work out the approx size of it on your leaflet layout.
Some people think that as modern inkjet printers print up to 5760 etc dpi that the need to have their image this size. This is not the case. for everyday or even professional printing, 300dpi will be plenty for full colour images.
Mono images such as lineart/clipart & text should be 600dpi for best results on small print.
If you wish to print images large then you can lower the resolution, in turn this will increase the size of the image. For example we will print large posters / canvases with image resolutions of 200 dpi as they are more likely to be viewed from a distance so dont need to be so high res.
Hope this helps.