Be precise though if you want to emulate the FIDE website. The international formula uses a table of look up values derived from this formula, not the direct formula.Peter Rhodes wrote:

Why not just calculate it yourself - this is the formula :

=((((10^((DIFF)/400))+1)^-1)+RES-1)*2*KFACTOR

where DIFF is the difference between your grade and your opponents.

RES is the Result (WIN=1, DRAW=0.5, LOSS=0)

KFACTOR - consult FIDE rules, but I think 16 is still used.

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Also the K factor is 10, 15 or 30. From memory K=10 if your rating has ever exceeded 2400, K=15 for most people, K=30 for players who haven't played enough games to qualify for K=15.