The K-factor (development coefficient)
K = K0 · b + a: base value by index and age, brake factor for losses below 1600, success bonus for juniors — the full table from WO Appendix 1.3.
Structure (WO Appendix 1.3)
K = K0 · b + a, rounded to one decimal place and capped at Kmax = 80 (Appendix 1.2.1).
K0 is the base value from the table below. b is the brake factor, a is the success bonus; both are usually 1 and 0 respectively and only apply in certain situations.
Age under WO 3.2 is the year the tournament ends minus the birth year — not the age on the day you play.
Base value K0 by DWZ index
The DWZ index counts how many times the DWZ has already been evaluated. Columns: index 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, above 10.
- Juniors up to 25 years old with a DWZ below 2200: 60 · 60 · 48 · 46 · 44 · 42 · 40 · 38 · 36 · 34 · 32
- Adults aged 26 or older with a DWZ below 2000: 60 · 60 · 44 · 42 · 40 · 38 · 36 · 34 · 32 · 30 · 28
- Adults from DWZ 2000 and juniors from DWZ 2200: 60 · 60 · 41 · 39 · 37 · 35 · 33 · 31 · 29 · 27 · 25
The higher the index, the smaller K0: an established rating moves more slowly than a young one.
Success bonus a — only when W ≥ We
- Juniors up to 20 years old with R0 below 2000: a = (2000 − R0) / 30. At R0 = 1400, that's 20 extra K points.
- From age 21 with R0 below 1600: a = 4.
- Otherwise a = 0. A result below expectation never earns a bonus.
This is why the birth year matters for the forecast: an 18-year-old at 1400 can gain considerably more from the same tournament than a 30-year-old.
Brake factor b — only when W < We and R0 below 1600
b = (R0 + 800) / (1600 + 800), independent of age. At R0 = 1200, b ≈ 0.83: losses have a dampened effect at low ratings.
In every other case, b = 1.
Frequently asked questions
Why is my K larger than in the table?
Because of the success bonus a: at W ≥ We, juniors under 2000 and everyone else under 1600 get a bonus added to K0 (WO Appendix 1.3).
Does my age on the day of the tournament count?
No. The WO uses the year the tournament ends minus your birth year (WO 3.2). Anyone turning 26 during the tournament year counts as an adult for the whole year.
What is the DWZ index?
The number of previous evaluations. An initial DWZ has index 1; it rises by 1 with every evaluated tournament. From index 11 onward, K0 no longer changes.
Source: DSB rating regulations, valid from 8 June 2026. Last updated: 14/09/2026. Unofficial explanation, not legal advice.