If you play regular, long time control, rated, over the board (OTB) chess games, you will have a fair idea of your rating, or playing strength. I play around 50 OTB games a year, so I can place some worth on the rating the ECF gives me.
At the moment, according to their update for the end of 2016, I have a rating of ECF 121, or 1608 Elo.
If you don’t play regular, long time control, rated, OTB games, there are a number of ways you could get an estimate of your rating (although I would argue none is a proper substitute for real gameplay). This could be by playing online, using a tactics trainer such as the one on chess.com, or the various options at Chesstempo (where you also get a FIDE estimated rating based on your performance in Standard tactics).
One tool I would not recommend you put much faith in, is the one supplied at Elometer. It was created by academics from the Dusseldorf University, but based on a sample of around five people reporting their results on the Chessable forums, it consistently overestimates ratings, in some cases by a large margin. Based on the 76 tactics and endgame problems you are asked to complete, it estimated my rating as follows: “Based on your move choices, our estimate of your Elo rating is 1945, with a 95% confidence interval of [1820…2070]. “. So that is almost 350 points above my actual rating.
Have a go, if no other reason, to do a bit of tactics training, but my advice would be to not pay too much attention to the outcome.