I have put the formula in excel to calculate fast how much points I would win or lose if I would go out the next person or an estimation if I would sit out.
This was handy for the last tournaments of the month, to know if I should just sit out after having collected a certain amount of chip or still fight for a higher place.
If you copy this text under here to excel (maybe you'll have to make some adjustments, but I'm sure you'll figure it out) and then you can just fill in what you know in the upper four fields (column C, row 1,2,3 and 4).
Field strength I estimated from how much points I won in the last tournament I played (changing the field strength with until the new score was the same as what I really won in the previous tournament).
Hope this helps
old score 2075,6
field strength 1560
new score =IF(C3/C4>0,25;C1+((LOG(C4/C3;2)-2)*10)+4+(C2-C1)/33;IF(C3/C4>1/16;C1+((LOG(C4/C3;2)-2)*20)+4+(C2-C1)/33;C1+(40+(1/16-(C3/C4))*16*40)+4+(C2-C1)/33))
points won =C6-C1