Exeter Chess Club: BCF-ELO chess grade conversion
- BCF-ELO chess grade conversion
- Calculation of grades and ratings
- Different classes and titles of player
- A course of study tailored to different levels of player
BCF-ELO chess grade conversion: revised
ELO=(BCF*5)+1250: 1 BCF point = 5 ELO points
N.B. USCF and ELO have the same form but I believe USCF ratings run a little higher than ELO: say, about 100 points on average. The data in the third to fifth columns is from Prof. Elo's book on The Ratings of chessplayers, past and present., although comparability between national systems is both difficult and occasionally controversial. See below for my attempt.The tables below are a bit of bodge numerically and in terms of HTML; they should be readable by text-only browsers like LYNX and graphical ones like Netscape; I try to avoid "enhancements" but Tables is good standard HTML.
| BCF | ELO |
|---|---|
| 80 | 1650 |
| 90 | 1700 |
| 100 | 1750 |
| 110 | 1800 |
| 120 | 1850 |
| 130 | 1900 |
| 140 | 1950 |
| 150 | 2000 |
| 160 | 2050 |
| 170 | 2100 |
| 180 | 2150 |
| 190 | 2200 |
| 200 | 2250 |
| 210 | 2300 |
| 220 | 2350 |
| 230 | 2400 |
| 240 | 2450 |
| 250 | 2500 |
| 260 | 2550 |
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generated by A Cool Blue Cat Perl programme |
Calculation of grades and ratings
BCF grades are pretty easy to calculate: you score for each graded game the current grade of your opponent if you draw, that grade +50 if you win, -50 if you lose (unless the grade difference is so great you might lose points for winning, in which case you assume the grades are 40 points apart and you score +10).ELO ratings are more sophisticated, and are based on statisticians' Normal Curve. Assume that the "class interval" (bottom of category A to bottom of category B) is 200 rating points. The distribution of scores of a player against someone their own strength is expected to fit the normal curve (upper graph) and the expected result against a player different to their rating by "x" class intervals follows the normal distribution function (lower graph).
Working out exact ELO scores from statistics tables (or using computers) is possible but not very practical. Fortunately the middle part of the function +- 1.5 class intervals is more or less straight and so you can pretend that it is straight for most purposes (a.k.a 'linear approximation').
So, to work out your rating performance in the ELO system, you can take the average rating of your opposition, work out your expected score, look at your actual score, and see how your rating should be adjusted. [There are some fiddles to cope with new players, but that's the gist of it.]
I was going to launch into the rest but both Arpad Elo and Joe Brooks have put it better than I could (but note that Joe's account has in mind the US context), and of course it is covered in the wonderful FAQ.
Glicko Ratings as implemented on the Free Internet Chess Servers (FICS) contain the fiddles for new players built in to the formulae used, so the same formula can be used by the computer for all players. This is a superb refinement to the ELO system but not readily implemented for pencil-and-paper tournaments.
Player classes and titles
Most GMs amd IMs come in the 'class' ELO 2400-2600. When Elo wrote, he regarded 2600 as 'World Championship Contenders', although now the term Super-GM is used in magazines (at least in the UK); to be a WC contender these days seems to require 2700.
The figure that ELo took as the top of "strong amateurs" was 2000 (BCF 175), although clearly many strong amateurs are better than that. The 'magic figure' in this country always seems to me to be 200 BCF (2200 ELO), as you will discover by talking to any UK player whose highest-ever grade is 199. It's the chess four-minute mile here, although you don't get called a master by reaching it.
To locate yourself in the scale of chess achievement there is a helpful guide in the FAQ to USCF classes and titles:
title range number (Percentile)This is hard to match up to the rest of the world since USCF ratings are not the same as ELO. I drew up the table below to help myself; I'd love to be told how to improve it.
----- ----- ------ ----------
Senior Master 2400 and up 252 100
Master 2200 - 2399 855 99
Expert 2000 - 2199 2,263 95
Class A 1800 - 1999 3,579 88
Class B 1600 - 1799 4,714 78
Class C 1400 - 1599 5,183 66
Class D 1200 - 1399 5,226 54
Class E below 1200 19,872 the rest of the pack
| LEVEL/ | BCF grades/ | ELO/ | USCF class/ | Eastern European category / |
|---|---|---|---|---|
| {D} Minor/ | BCF 75-100/ | ELO 1625-1750/ | Class D or C | category 4 / |
| {C} Intermediate/ | BCF 100-125/ | ELO 1750-1875/ | Class C or B/ | category 3 / |
| {B} Major/ | BCF 125-150/ | ELO 1875-2000/ | Class B or A/ | category 2 / |
| {A} County/ | BCF 150-175/ | ELO 2000-2125/ | Class A or Expert/ | category 1 / |
| Top county players/ | BCF 175-200/ | ELO 2125-2250/ | Expert or NM/ | Candidate Master / |
| / | / | ELO 2200-2300/ | US NM or SM/ | National Master / |
| / | / | ELO 2300-2400/ | US SM (USCF 2400+)/ | National Master / |
| International Master/ | BCF 220-240/ | ELO 2360-2520/ | / | / |
| Grandmaster/ | BCF 240-250/ | ELO 2520-2600/ | / | / |
| Super-GM/ | BCF 250-270/ | ELO 2600-2700+/ | / | / |
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This document (bcftable.html) was last modified on 17th Sep 96
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