My mattress is 39 by 80 what bed frame is it fit ? like Metal Platform Bed,?
That's a twin. Actually, that's a twin-long, twin XL. It's the size mattress they put in college dorm rooms. If it has a box spring, you can put either on the same Hollywood frame (standard metal frame), so long as the foot is open rather than closed with brackets to attach a footboard to. If its a twin Hollywood frame that you can attach a footboard to, it'll be too short. Your mattress and box spring won't sit on it because they're too long. If it's sheets you're looking for, you might be able to find some twin-long sheets online, but generally speaking, all be supplies for twin-long (twin XL) only come out once a year in the fall when kids go into the dorms. That's because 99% of all twin-long beds are in college dorm rooms. They don't exist anywhere else because stores don't sell them. It's an irregular size made especially for colleges, along with some other institutions, like the military and prisons. The only way the average consumer comes across such a bed other than in a college dorm room is as one-half of an adjustable king size bed where both sides are independently adjustable, hence the 1% not in college dorms.
Twin XL is your size.
XL twin size mattress, so you would need an XL twin frame.