GameCalc

Chess Elo Rating Calculator

See how a win, draw, or loss changes your rating.

Your Rating

Opponent Rating

Result

K-Factor

New Rating

1,516

Rating Change: +16
Expected Score: 0.5

What you entered

Your Rating: 1500Opponent Rating: 1500Result: winK-Factor: 32

1
Calculate expected score
1 / (1 + 10^((1500 - 1500) / 400))= 0.5
2
Actual score from result
win = 1= 1
3
Rating change
32 × (1 - 0.5)= +16
4
New rating
1500 + (16)= 1,516

Result

New Rating: 1,516

Elo rating change by result and rating gap

Your expected score comes from the rating gap alone; the change is K times the difference between what you scored and what was expected. Rows use K = 32.

Your rating	Opponent	Result	Expected score	Change	New rating
1500	1500	Win	0.5000	+16.0	1516.0
1500	1500	Draw	0.5000	0.0	1500.0
1500	1500	Loss	0.5000	-16.0	1484.0
1500	1700	Win	0.2403	+24.3	1524.3
1500	1700	Loss	0.2403	-7.7	1492.3
1500	1900	Win	0.0909	+29.1	1529.1
1700	1500	Win	0.7597	+7.7	1707.7
1700	1500	Loss	0.7597	-24.3	1675.7

A 200-point gap means the favourite is expected to score about 76%. Beating a much stronger player gains you nearly the full K value, while losing to them costs very little, which is what makes the system self-correcting.

How the Elo system works

The Elo system, invented by Arpad Elo, predicts the probability of winning based on rating differences — if you're rated 200 points higher than your opponent, the formula expects you to win about 76% of the time, and you gain fewer points for a predictable win than for an upset.

What the K-factor controls

The K-factor determines how much a single game can change your rating — beginners use K=40 so their rating adjusts quickly to their true level, while established players use K=16 or K=32 for more stability.

Frequently asked questions

My Elo is 1200 and I beat a 1500-rated player — how much does my rating go up?

With K=32, you'd gain about 24 points (to ~1224). The formula expected you to win only 15% of the time, so the upset earns a big reward. If you'd lost, you'd drop only about 5 points.

How is Elo different from the USCF or FIDE rating?

USCF and FIDE both use Elo-based systems but with different K-factors, floors, and bonus rules. FIDE uses K=40 for new players, K=20 for established ones, and K=10 for 2400+ rated players, while USCF has its own variable formula.

Can my Elo rating go below zero?

Theoretically the formula can produce negative ratings, but in practice rating floors prevent this — FIDE floors ratings at 1000, and most online platforms set their own minimums (e.g., Chess.com floors at 100).

Does a draw always cost the higher-rated player points?

Yes. If you're rated higher, the formula expects you to win more than 50% of the time, so a draw counts as an underperformance and you lose a few points while your opponent gains them.