Decode X's For You feed

X open-sourced the code that ranks the For You feed. We explored it and decoded the weights, penalties and enforcement rules. Now test them yourself: set a post's predicted actions, see the score, and simulate repeat posts and reports.

Created by @SidneyCur · Based on the repository at commit b412112 (2026-10-03)

Open the calculator See worked examples

Example +2.00

A reply on your original post, from a mutual follow

The reply weight is 5, plus a 15 boost for mutual follows on original posts: 20 in total. A 10% predicted chance of a reply adds 20 × 0.10.

20 × 0.10 = +2.00

How a score is built

The ranker does not count likes. It predicts how likely each action is for each viewer, weights each prediction, and adds the results. The four steps below are the same ones the calculator runs.

Predict

The Phoenix model estimates the chance a viewer will reply, like, share, follow, mute, or report a post.

Weight

Each chance is multiplied by a fixed weight. Copy-link shares carry 20, a report carries −234.

Sum

The weighted values are added. Positive actions push the score up and negative ones pull it down.

Adjust

An offset keeps scores non-negative. Out-of-network posts are scaled by 0.75, and each extra post from one author is scaled down.

Weights are not counts. A weight of 5 on replies means a 10% chance of a reply adds 0.5 points, not five.

Score calculator

Set the predicted chance of each action for one post. P, the chance, is a percentage from 0 to 100. The values are illustrative: start from a preset, then adjust. Results update as you type or drag.

Estimates only. The chances and results are illustrative inputs, not measurements from X. feedecoder cannot guarantee any score, reach or outcome for your posts.

Original post from a mutual followAdds 15 to the reply weight, so a reply scores 20 instead of 5. The Weight column shows the change.

Predicted chance of each action, per viewer
Action	Weight	Chance (%)	Slider	Points

Viewer does not follow you (OON, out-of-network)Scales the score by 0.75 for posts from accounts the viewer does not follow.

Position of this post in the viewer's feed (k)k is the post's place among your posts in one feed. A 3rd or later post is scored as 3rd.

Final score 0.000

Before the adjustments 0.0000

Adds points Subtracts points

The offset is a constant, 0.001, that the ranker adds so scores stay non-negative. A net total below zero is compressed toward zero, so the post ranks at the bottom.

Feed simulation

Two things the ranker does to your posts. First, it discounts repeat posts from one author. Second, one report can outweigh many good actions. Both use the code's own constants.

Estimates only. The sliders show how the code's constants combine. They are not predictions for your account, and feedecoder cannot guarantee any reach or outcome.

Your posts in one viewer's feed

Posts from you in one feed 6

Starting score per post 2.00

Kept by the postRemoved by repeat-post decay

Repeat-post decay in one feed
#	Post	Multiplier	Factor	Score

The multiplier for post k is (1 − 0.25) × 0.5^k−1 + 0.25. It falls quickly, then levels off at 0.25 and never reaches zero.

Break-even: how many reports cancel a reply?

Reports carry −234. A boosted reply carries +20 per unit of chance. Use the slider to test a report chance.

Chance of a report (%) 0.10%

Boosted reply, from the calculator+0.40

Report at this chance−0.23

Report chance that cancels one boosted reply0.17%

Worked examples

Each row is one calculation from the weights above, with illustrative chances. Read the result first, then the calculation and what it means for your posts.

Worked examples
#	Case	Result	Calculation	What it means
01	Boosted reply on your original postLargest gain	+2.00	`20 × 0.10 = +2.00`	A mutual follow is 10% likely to reply to your original post. Only original posts from mutual follows get the boost.
02	Copy-link shareLarge gain	+1.00	`20 × 0.05 = +1.00`	Five in a hundred viewers copy the link to your post. Copy-link is the largest non-reply gain, so posts people want to pass on are worth designing for.
03	One report, at a 1% chanceLargest loss	−2.34	`−234 × 0.01 = −2.34`	A report weighs −234. A 1% chance of reporting cancels several good actions, which is why report rates matter most.
04	A 2% mute chance against a 30% favorite chanceMute vs favorite	−1.18	`−58.8 × 0.02 = −1.18 · 0.5 × 0.30 = +0.15`	A mute weighs −58.8, so a 2% chance costs about eight favorites' worth of gain (+0.15 at 30%).
05	The same boosted reply, for a viewer who doesn't follow youOut of network	1.50	`2.00 × 0.75 = 1.50`	An out-of-network post keeps 75% of its score. Replies and reposts from accounts a viewer doesn't follow are filtered by default.
06	Your fourth post in one viewer's feedFourth post	0.69	`2.00 × 0.344 = 0.69`	Each later post from you is scaled down: the 4th keeps 34% of the starting score. Posting less often reduces how many of your posts compete in one feed.
07	The tenth post and beyondFloor	0.25	`0.25 + 0.75 × 0.5⁹ = 0.2515`	The multiplier approaches 0.25 but never reaches zero, so a late post still scores a quarter of the starting value.
08	Report chance that cancels one boosted replyBreak-even	0.85%	`2.00 ÷ 234 ≈ 0.85%`	At a 10% reply chance, a boosted reply is worth +2.00. About one viewer in 117 reporting cancels it out.

Follower goal planner

The code ranks posts. It does not model how many people follow after reading one, so this planner needs your own rate. Start from your analytics: 60 new follows and 227 replies in a week gives about 0.26 follows per reply, counted gross.

Estimates only. Your rate is an input, so the result is a projection, not a forecast. feedecoder cannot guarantee follows, replies or reach.

Current followers

From your analytics.

Target followers

The number you want to reach.

Days

The time you have to reach it.

Follows per reply

Your measured rate. Test it over a week before relying on it.

Replies you post per day now

Used for the comparison below.

Do and don't

Each item links to a weight or a rule in the repository. Points are the change to a post's score. Labels are enforcement flags that last 30 days.

Raises the score

Post original posts to mutual followsReplies to them carry 20 instead of 5. reply + boost
Earn copy-link sharesWorth 20 per unit of chance, the largest non-reply gain. ShareViaCopyLinkWeight
Earn quotes and DM sharesEach worth 5. QuoteWeight, ShareViaDmWeight
Earn followsWorth 4 per unit of chance. Clear posts that show what you know help. FollowAuthorWeight
Reply to followers and mutualsTheir replies to you stay in the feed. Replies to strangers are filtered by default. OONRetweetReplyFilter
Post regularly, within 48 hoursPosts older than 48 hours are removed before scoring. MAX_POST_AGE

Lowers the score or gets labelled

Trigger reports, mutes, blocksReports −234, mutes −58.8, blocks −31.2 per unit of chance. ReportWeight
Automate or burst repliesFlagged as fast-reply spam: a 30-day label that drops the post for people who don't follow you. fast_reply_spam_post
Post LLM-written or gibberish repliesFlagged as LLM text or gibberish. Gibberish gets a 30-day spam label. llm_slop_post, gibberish_post
Repeat near-identical repliesThe multi-step classifier flags them across threads. classifier_multi_step_reply_spam
Count on video views or profile clicksBoth carry zero weight in this code. VqvWeight, ProfileClickWeight
Post a fourth or later item in one feedScaled to about a third of its score. EnableAuthorDiversity

Questions

What is feedecoder?

feedecoder is an independent reference for X's For You feed. It explains the public ranking code, turns its scoring weights into a calculator and simulation, and lists the enforcement rules, with sources.

Is feedecoder affiliated with X?

No. feedecoder is independent and is not affiliated with, endorsed by, or sponsored by X Corp.

Where do the numbers come from?

Every weight comes from the public repository x-algorithm, commit b412112 (2026-10-03). The repository's parameters are mirrored from feature switches, so production values may differ. The probabilities in the calculator are illustrative.

How is a post's score calculated?

The ranker predicts how likely each action is, multiplies each prediction by its weight, and adds the results. An offset keeps scores non-negative. Out-of-network posts are scaled by 0.75, and each extra post from one author is scaled down.

Why do replies to strangers reach fewer people?

In the repository, out-of-network replies and reposts are filtered by default, so replies mostly reach your followers. Original posts are the route to new people.

Sources and limits

Weights and fusion: home-mixer/params/param.rs, vm-ranker/params.rs, xai-value-model/scoring.rs.

Filters: home-mixer/filters/. Enforcement: abuse-enforcement-service/service-lib/rules/, visibility-filtering/rules/, grox/flows/reply_spam/.

The repository's parameters are mirrored from feature switches, so production values may differ. The probabilities are illustrative, not measured for any account. Classifier thresholds are not published.

Design direction: the light, ticket-style reference at leavingfrance.com. No assets were copied.