What size coop do I need?

[Tiffy316]

Is your run fully covered and weatherproof or will they be confined to the coop much of the time?

I don't know if anyone ever regretted making a coop larger than they thought they needed.

It's just gonna be a little place for them to go inside and get out of the weather/sleep. They're really small. Thry dont take up much space.

 

[U_Stormcrow]

It's just gonna be a little place for them to go inside and get out of the weather/sleep. They're really small. Thry dont take up much space.

Abundance is a social lubricant. Its not simply a question of whether or not they physically fit. And actually, your winters (however miserable they may be for us humans) aren't nearly so brutal as your summers. Chickens, even your little banties, have down coats they can't take off. Compared to us, they do winters well, and heat poorly.

I'm going to join the others in recommending the biggest coop you can reasonably afford, and remind further that using multiples of regular sizes saves cutting, speeds construction - while squares are more resource efficient than rectangles. A 4x12 shed uses as much lumber and panel as an 8x8, but has only 3/4 the space. With lumber prices back closer to "normal", I'd suggest an 8x8 coop with an 8x8 run, and further, suggest the coop be open air on one side. I also suggest in be walk in height. That gives them plenty of space, allows the coop to dual purpose as run, provides weather protection/shelter without the stifling heat concerns in high summer, saves materials costs, and is easily expanded later. Also, whatever space you don't use can serve a second purpose - storing feed, garden tools, whatever.

Oh and a single slant "shed" style roof is easiest to build, with large overhangs. Orient the back (solid) wall in the direction of your prevailing winds during your wettest season. Cold air doesn't kill chickens, cold water does.

 

[3KillerBs]

It's just gonna be a little place for them to go inside and get out of the weather/sleep. They're really small. Thry dont take up much space.

You said that you had nasty winters, which means that they'll be in out of the weather most of the time for months. They need room to do all their chicken things in shelter -- either a large coop or a smaller coop with a run that has a roof and some protection on the walls (many people put plastic on the windward side for the winter).