---
title: "US Chess (USCF) rating estimator"
url: "https://georgelichess.com/tools/uscf-rating-estimator.md"
canonical_url: "https://georgelichess.com/tools/uscf-rating-estimator"
last_updated: "2026-11-05"
type: "tool"
summary: "Estimate your US Chess rating change after an event with the published formula: expected score, K from effective games and the bonus, worked step by step."
related: ["https://georgelichess.com/tools/rating-calculator.md", "https://georgelichess.com/chess-ratings-explained.md", "https://georgelichess.com/tools/performance-rating.md"]
---

# US Chess (USCF) rating estimator

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Estimate your US Chess rating change after an event with the published formula: expected score, K from effective games and the bonus, worked step by step.

This estimator shows how your US Chess rating changes after one event. It uses the standard formula from the published US Chess rating system: the score your rating predicts, a K factor set by how many games your rating rests on, and a bonus for an unusually strong result. Enter your rating, your games and the results.

## How the new rating is computed

New rating = rating + K x (points scored - expected points) + bonus

Expected points for one game = 1 / (1 + 10 ^ (-(your rating - opponent rating) / 400))

K = 800 / (effective games + games in the event)

Effective games = the smaller of your games before the event and N*, where N* = 50 / square root of (0.662 + 0.00000739 x (2569 - rating)^2) up to a rating of 2355, and 50 above it

Bonus = the larger of 0 and K x (points scored - expected points) - 10 x square root of the larger of 4 and the games in the event

The result is rounded to a whole number, and no rating falls below 100.

## Effective games by rating

| Rating | Most games that count |
| --- | --- |
| 1,000 | 11.51 |
| 1,400 | 15.24 |
| 1,700 | 20.01 |
| 2,000 | 28.61 |
| 2,300 | 45.71 |
| 2,355 | 49.99 |
| 2,400 | 50.00 |

## Dual-rated events

When an over-the-board regular event has a time control from 30 to 65 minutes and your Regular rating is above 2200, K for the Regular rating is 800 x (6.5 - 0.0025 x rating) / (effective games + games in the event) below 2500, and 200 / (effective games + games in the event) from 2500. The lower K applies to the Regular rating only; a Quick rating keeps the standard K.

## Worked examples

One event each, for a player rated 1700 with 30 games before the event unless the row says otherwise. The opponents in the first row are rated 1650, 1700, 1750 and 1800; in every other row all four are rated 1700.

| Event | K | Score | Expected | Bonus | Change | New rating |
| --- | --- | --- | --- | --- | --- | --- |
| Four games, a win, a draw, a loss and a win (the calculator opens with it) | 33.32 | 2.5 | 1.86 | +1.33 | +23 | 1,723 |
| Four wins against equal opponents, 30 games before the event | 33.32 | 4 | 2.00 | +46.63 | +113 | 1,813 |
| The same four wins, 100 games before the event | 33.32 | 4 | 2.00 | +46.63 | +113 | 1,813 |
| The same four wins, one opponent met three times | 33.32 | 4 | 2.00 | 0.00 | +67 | 1,767 |

## What the estimate leaves out

The second rating pass that uses your opponents' first-pass ratings, rating floors above 100, ratings of unrated opponents, and players whose rating rests on 8 games or fewer or who have only ever won or only ever lost, which US Chess computes with a different algorithm.

For the FIDE version of this calculation, use the [chess rating calculator](https://georgelichess.com/tools/rating-calculator.md).

## Questions people ask

**Is this my official US Chess rating?** No. It estimates the result of one event from the numbers you enter. US Chess rates an event in two passes and uses each opponent’s first-pass rating in the second, while this tool uses the ratings you type for both. The official figure can also differ when a rating floor applies or an opponent has no rating yet.

**Why does the tool refuse a rating built on 8 games or fewer?** US Chess uses the standard formula once a rating rests on more than 8 games. Below that it runs a different, iterative algorithm over the whole event, and so it does for a player who has only ever won or only ever lost. The tool stops and says why when you enter 8 games or fewer. It has no box for a history of only wins or only losses, so it cannot see that case: if that is you, the standard formula it shows is not the one US Chess uses.

**What are effective games?** A rating built on many games is less reliable at a low rating than at a high one, so US Chess caps the games that count. A 1700 rating counts for at most 20.01 games however many you have played, which keeps K near 33 for a four-round event. Above 2355 the cap is 50 games.

**What is the bonus?** It is a second payment for a result far above what your rating predicts. When K times the gap between your points and your expected points is larger than 10 times the square root of the rounds (counting a 3-round event as 4), the excess is added again. It needs at least 3 games and no opponent met more than twice, or once in a 3-game event.

**Does it work for blitz, quick and online ratings?** The formulas are the same for all six US Chess rating systems, and the rated systems are computed separately, so enter the rating and game count from the system the event belongs to. The dual-rated tick applies only to a Regular rating, at over-the-board events with a time control from 30 to 65 minutes; leave it unticked for a Quick or Blitz rating.

**What do I enter for an unrated opponent?** The tool needs a number for every opponent. For an opponent with no rating in that system, US Chess builds a starting rating from the opponent’s other ratings (the other US Chess systems, FIDE and the Canadian federation) or, with none, from age. This tool does not reproduce that step, so enter your best figure and expect the result to differ more from the official one.

**Is this the FIDE formula?** No. FIDE reads expected scores from its own table and uses its own K factors. The chess rating calculator on this site follows the FIDE Handbook; this page follows the US Chess system.

## Sources

The US Chess Rating system, Mark E. Glickman and Thomas Doan, April 6, 2026, read 2026-11-05. https://www.glicko.net/ratings/rating.system.pdf

## Related

- [Chess rating calculator: FIDE and Elo](https://georgelichess.com/tools/rating-calculator.md)
- [Chess ratings explained](https://georgelichess.com/chess-ratings-explained.md)
- [Chess performance rating calculator](https://georgelichess.com/tools/performance-rating.md)