Rating live chess.com vs...

Hi, I have kind of frequent question here, but I can't found topic where it is really explained. I think about join some open tournament and I want to know what rating range I'm.

Have chess.com live long rating any relation to FIDE/USCF rating? I found that some players have about 100 points higher FIDE rating that their rating in long live games, is it truth? I know that it's difficult to compare rating systems, but in general FIDE rating is +- ??? to chess.com long live.

btw.My current long live game rating is about 1500, but just after few games it should be lower.

Thanks for answer.

It's not difficult to compare, its IMPOSSIBLE. It can't be done with any degree of accuracy, and anyone who tells you different doesn't understand how ratings work.

Play in the lower section, and see how you fare OTB. Then you'll have a good base to work on. Don't assume anything. You may be playing better or worse OTB than live. You'll know when you give it a try... 

Very true hicetnunc.  OTB is such a different form from online it is impossible to translate ratings. 

Your first OTB should probably be in the lower sections, and then your results will give you a great gauge on where you should enter your next one! :)

Ok, I understand that there is a big difference in OTB and online live, but I can't get why is impossible to say it might be higher/lower about 50 000 points in very low accuracy and just in some cases? Every rating just shows relative level of skill. I don't want exact number. When forget about all the difference, is it still impossible to say  your are 1500 here you might be 750-1200 in fide with very low accuracy? I'm just curious and I don't want waste my money and time to go and join some tournament and recognize that I cant win/draw one game even in lowest section. I understand that if you told me some rating range that it might not be right, but... something is better than nothing.
If its really impossible ok thanks for helping me.  

I hear you.  The challenge in this comes from many angles, but time contols is a biggie.  If you have a 1500 rating in blitz, it does not really translate to an OTB comparision with TC's of far longer.  

I will post this with the caveat that this is just my stats and not intended to be cross referenced as an answer, just an example lol.

As of today my Chess.com grades are: 1596Blitz, 1759Online

USCF Grade is  1798, Scottish is 1599(regular) 1728(blitz), ECF is 130

For whatever it means, I hope it helps =D

If you're 1500 in live standard here, expect something like 1200-1700 in OTB, but that's just a rough estimate.

Now go, and get your feet wet 

You don't have to start with an expensive tournament either. Try to a club in your area (list of chess clubs in the Czech Republic) and ask a stronger player to estimate your playing strength.

Thanks all of you. I will try some club.