My pictures from my nikon camera come out blurry on instagram?

I have a Nikon D3100 and my pictures are perfectly fine on every other site, they don't look blurry or pixeled. But for some reason when I try to post them on instagram it makes the pictures really blurry and look pixeled. I've noticed some other people who have Nikon cameras don't have this problem. I have an Android phone and I love sharing my pictures through Instagram but the pictures come out terrible. Any idea what I could do to fix this issue? Did anyone else have this problem?

Instagram compresses photos A LOT. If you want your camera photos on instagram (and I can't think of a reason why you would), you need to adjust your photos to match the resolution of the normal instagram photo.