The limit is 200K BUT, larger ones will load, but not if there is a few of them. A 250K file will load, but 6 that size won't. You will get a message saying it failed.
Quick fix. Download Irfanview and resize to 1280 (along the longest side). Irfanview defaults it's resizes to 72px/inch and that will get it down below, or close to, the size u need while giving a good clear picture..
File size is also determined by the amount of detail in a photo. A picture of a bedsheet
v one of a pebblie beach will be considerably different in sizes.
My jpg's are 5~7mb out of camera and between 100~300k resized
http://www.irfanview.com/ - will open RAW files too, and save to a dozen different formats (GIF is smaller than JPG is smaller than BMP)
Hope it helps
Trevor