As players get better games are won based on smaller and smaller advantages, so it depends on how much your opponent can make of this advantage. So instead of how much it decreases your rating maybe we could look at how much different handicaps increase other player's ratings.
Players under 1000... hard for me to judge because I don't have much recent experience playing them. Lets say a 1000 rated player vs another 1000 rated player wins a knight early in the opening, is that going to be a guaranteed win? I don't think 100% guarantee. What about if 1000 vs 1400 and the 1400 loses a knight early in opening? Not sure but I may still like the 1400s chances.
So yeah, I'm going to totally guess below, but here's off the top of my head...
rating | pawn | knight | rook |
800 | +0 | +50 | +80
1000 | +20 | +150 | +200
1200 | +30 | +200 | +300
1400 | +50 | +300 | +400
1600 | +50 | +400 | +500
1800 | +80 | +500 | +600
2000 | +100 | +600 | +700
Giving more than 1 piece, or giving a queen should be even more exponential... although with some limits of course as you start to get lower class players vs titled players you'd see the titled players preform an all out attack and likely mate the other guy so hard to say.
Anyway with my quick numbers with little experience to back them, you could be giving these U1000 players rook odds without much trouble :) In this case I imagine you not going for an all out attack, but just some solid opening, avoiding all trades, and over time they'll give you the material back with mistakes.
Hello i've recently been helping out at a local club by teaching and playing lower rated players (below 1000) and beginners. Well to set an exampleof someone the head coach of the club told me to play someone around 1100ish with odds of a pawn. Already nervouse a bit since 1100 isn't to far down away from my rating and it being my first ever odds game I played and to my delight won the game. So afterthis I started to play more odds games and won every single game that day and during all these games I gave bigger odds but noo higher than a knight. At the end of the day I made this what I believe to be a good assessment of proper handicaps but wanted to know what other's think.
Rook handicap = players 1000 below my stregth.
Bishop or Knight= players 600-800 below my stregth
Pawn = players 300-500 below my stregth
extra move = 200 below my stregth.
I'd love to know what everyone else thinks of handicap game's and how you treat them.