The short answer: “half-life” in DUPR is about recency. Old matches count for less than new ones, so your DUPR rating reflects how you play now, not how you played last year. DUPR’s help center puts it plainly: “A match played today influences your rating more than one played six months ago” (DUPR Help Center, updated September 2026).
What changed: you may have seen a “Half-Life” number in older DUPR discussions and screenshots, like the 3.79 below. DUPR’s current help center doesn’t document a half-life metric. The confidence measure players see today is the Reliability Score, a 1–100% figure built from your matches over the last 6–12 months. If you’re looking at a half-life number on an old screenshot or tournament page, read it as an older measure of how much recent play a rating was based on.
What “half-life” means
Half-life is a term from physics and statistics. In a system with a half-life, something loses half its weight every fixed period. A rating system that uses one gives every match a weight that shrinks as the match gets older:
- A match played today counts in full.
- After one half-life, it counts half as much.
- After two half-lives, a quarter. After three, an eighth.
It never quite drops to zero, but a match from long ago has almost no say in your rating.
An illustration of exponential decay. DUPR doesn't publish its decay rate; it only says recent matches count more than older ones.
Source: Pickleland illustration of exponential decay (weight = 0.5^age÷half-life)
DUPR doesn’t publish its exact formula or decay rate. What it does say, in its help center:
- Recent matches have a bigger impact than older ones. “A match played today influences your rating more than one played six months ago.”
- Recent volume makes your rating stable. “If you have a lot of recent matches, your rating is considered more reliable and will change less with each new result.”
- Few or old matches make it jumpy. “If you’ve played fewer or older matches, your rating may shift more as the system learns about your current skill level.”
How it connects to the Reliability Score
The Reliability Score is the recency idea in visible form. DUPR’s formula considers “the number of matches played (and the match source), plus the variety of partners and opponents over the last 6–12 months.” It rises as you add matches and “begins to decrease after an extended period with no matches played” (What is the Reliability Score?). Our full guide: DUPR Reliability Score explained.
| Recency weighting (“half-life”) | Reliability Score | |
|---|---|---|
| What it does | Decides how much each match counts in your rating | Shows how confident DUPR is in your rating |
| Shown on your profile | Not in DUPR’s current documentation | Yes, 1–100%, separately for singles and doubles |
| Time frame | Older matches fade gradually | Built from the last 6–12 months |
| Updates | With each new match | Every Tuesday |
What this means for you
If you’ve been away for a while, your next few matches will move your rating more than usual. DUPR calls this a calibration phase: when you “return after a long break, you might notice significant changes in your rating” (DUPR Help Center). Don’t panic about a big drop after a rusty first week back.
If you play every week, each result moves you a little. A single bad night won’t sink your rating.
If you’ve improved a lot, play more recorded matches. Your old results are fading anyway, and new ones will pull your rating toward your current level faster.
If your rating went down after a win, that’s not half-life. DUPR compares your score with the expected score, so a narrow win as the favorite can lower your rating. See why your DUPR went down after a win.
Frequently Asked Questions
What is DUPR half-life?
It’s the idea that older matches gradually count less in your DUPR rating, so recent results matter most. DUPR’s current help center describes this through its rating algorithm and the Reliability Score rather than a separate half-life number.
Do old matches still count on DUPR?
They count less as they age. DUPR says a match played today influences your rating more than one played six months ago, and the Reliability Score looks at your last 6–12 months.
Why did my DUPR change so much after a break?
When you return after a long break, DUPR treats it as a calibration phase and your rating can move more than usual until it has recent results again.
How do I keep my DUPR rating stable?
Record matches regularly, ideally club or tournament matches with a variety of partners. Lots of recent data means each new match moves your rating less.
Is half-life the same as the reliability score?
They’re related but not the same. Recency weighting decides how much each match counts. The Reliability Score is the percentage that shows how confident DUPR is in your rating.