Information about the FPL Price Change Algorithm
Note that this guide borrows from the excellent work done by
reds363 in the 2010/11 season. I am updating as best I can with what we believe to be true in 2017. If you spot a discrepancy or inaccuracy, report it by posting below and I'll update this post.
As you may be aware already, the prices of players in FPL can vary throughout the season. Players can rise or drop in price dependent on the number of managers buying or selling a particular player. When a player is transferred in by a lot of managers, then his price may rise, and similarly if a player is transferred out by a lot of managers then his price may drop.
FPL closely guard the exact algorithm that decides if and when players rise or drop in price, but over the years many of the rules have been reverse engineered and a list of what we believe to be true currently is shown below. I say what "we believe to be true" since FPL have never confirmed or denied any of these assumptions, and FPL Towers would be free to add or remove rules at any time.
The basic rules - price changes
Q: How often do players change in price?
A: Players can change in price once per day (by 0.1m) either rising or falling by that amount. Players cannot rise or fall more than once in a single day. Additionally, a player can only rise (or fall) 3 times in a given gameweek.
Q: At what time do players change in price?
A: There's no set time, although usually price changes all happen in one go at 01:00am GMT (02:00am BST). However, this is not a hard and fast rule and sometimes price changes have occured later than this time. You should assume price changes could occur in a window between 00.30am and 03.30am GMT.
Q: What causes a player to rise in price?
A: The simple answer is transfers in cause a player to increase in price, however the precise answer is a little more nuanced that that. A player will rise in price when his "Net Transfers In (NTI)" (that is his total transfers in minus his transfers out) hits a certain threshold.
The threshold can change through the season depending on the number of active managers in FPL, and FPL themselves may tweak the number to make price changes more or less aggressive. This season, the threshold started at around 55,000, while last season (2016/17) the NTI threshold varied through the season from around 45,000 to 21,500. That means that once a player's ownership has grown by the threshold (let's say 55,000) then he will rise in price by 0.1m (there is more to the precise answer than that, please see the advanced rules section below for details if you are interested).
Q: What causes a player to drop in price?
This is similar to rises, except that for a price drop to occur a threshold of "Net Transfers Out (NTO)" (that is his total transfers out minus his transfers in) must be breached. The exact level of the NTO threshold for any given player is the lower number of either:
1) The negative of the NTI threshold value (for players who have already risen in price during the season)
2) OR 10% of their ownership (for players who are at or below their season starting price)
The key difference between rises and drops is that the price rise threshold is the same for all players while the number of transfers required to affect a price drop is different for each player. We also believe that there are differences in how multiple price drops or multiple price rises within a single GW work (please see the advanced rules section for details on that).
The basic rules - flags & price protection
Q: Can flagged players drop in price?
Yes!! When a player is flagged in FPL (either red, orange or yellow) then they can still change in price. A flagged player is not protected from price drops, however the NTO threshold does increase under certain circumstances. That means that a flagged player may require more NTOs to effect a drop, but that they can still drop!
The exact rules in this area are not 100% known, but to the best of our current knowledge the following is true;
- A player with a red flag will have roughly between 2x and 3x his usual NTI/NTO target. This exact value of the multiplier can vary for individual players and circumstances, but the thing we're quite certain of is that a red flag does increase the required threshold.
- Red flags (injury) - a popular (i.e. well owned) player red-flagged due to injury could have as much as a 3x multiplier on his usual NTO/NTI target. For lesser owned players, we think this reduces to around 2x the NTI/NTO threshold. Very low ownership players have a threshold around 2.5x.
- Red flags (suspension) - a player red-flagged with a suspension appears to have a multiplier somewhere between 2x and 2.5x his usual NTI/NTO target. Note that this could be less than the multiplier for an injured player.
- Orange and yellow flags do not, we think, alter the NTI/NTO threshold. In past seasons there did used to be a multiplier on orange or yellow flags, but we think this no longer applies and therefore NTO/NTI targets for yellow or orange flagged players are the same as for unflagged players.
Q: Can flagged players still rise in price?
In theory, yes. The NTI threshold for a price rise is not believed to be affected by a flag. However in practice, the behaviour of FPL managers is such that flagged players are rarely in Net Transfer In territory so the theory is rarely tested.
Q: Are players that have been unflagged protected from price changes?
This depends on the nature of the unflagging.
Red (for more than 2 days) => Clear: A player will enjoy 8 days of price protection and cannot rise or fall in price during this window.
Yellow => Clear: There is no price change protection.
Orange => Clear: There is no price change protection.
Red => Orange/Yellow => Clear: There is no price change protection.
CtC will show you when a player was unflagged, and how long their protection window (if applicable) lasts for.
Q: Are newly transferred players price protected?
If a player is newly added to FPL (perhaps he joined in the January transfer window for example) then he would be price protected for 8 days. If he has just transferred between clubs (and he already existed in FPL) then he would not be price protected.
The advanced rules - price changes
Q: Are the NTI/NTO thresholds constant?
FPL may change the thresholds at any time, but we generally believe that the threshold is related to the number of active managers in the game. Since the number of active managers decreases during the season, then the NTI/NTO thresholds may change. CtC keeps track of this for you, however, so you don't have to adjust for this yourself.
Q: When calculating price changes, do wildcard transfers count?
No. This is one of the reasons that CtC is a guide rather than a definitive resource for price rises - not all transfers in are equal (in terms of contributing to price rises) and the data visible to CtC does not allow us to determine which transfers do contribute to the NTI/NTO threshold.
The main issue is Wildcard transfers in/out, which are thought not to count toward the NTI/NTO threshold, are not published by FPL. When we talk of the NTI threshold, we mean net transfers in excluding wildcards. The assessment of how close a player is to a rise or drop therefore requires CtC to make an estimate of the ratio of the two types of transfer accrued by any given player.
Q: If a player is way over their NTI threshold and changes in price, what happens to all the extra transfers?
This is probably best illustrated with an example. So, lets assume that a player requires 55,000 NTI to achieve a price rise. Let's also assume that he receives 40,000 NTI every day. By the end of day 2, our player has received 80,000 NTI and he therefore qualifies for a price rise of 0.1.
At this point, because his price changed, then his current NTI number is reset to 0 and so the extra 25,000 NTI that our player had are, in effect, lost and will not contribute at all to his next potential price rise.
Q: If a player has risen once this gameweek, how many transfers are required for him to rise a second or third time in the same GW?
FPL apply what we call multipliers in this situation. So a player may require 55,000 NTI for his first rise, but that number will multiply to 2x the value (so 110k ADDITIONAL transfers) for each of the second and third rises.
Q: Do multipliers apply to drops?
We don't believe so. Remember that a player will drop when his NTO hits the lowest of
1) The negative of the NTI threshold value (for players who have already risen in price during the season)
2) OR 10% of their ownership (for players who are at or below their season starting price)
The critical difference between rises and drops appears to be that there is no multiplier applied to price drops. In practical terms, this means a player may drop in price faster than they rose, if they are above their season starting price.
Q: When are multipliers reset?
When the GW deadline passes any multipliers in effect are dropped. That means that players will once again just require the 55,000 NTI threshold to rise in price.
So if a player had risen in price last GW, but not reached the second rise threshold (due to the 2x multiplier being applied) but he was in excess of the basic NTI threshold, then he would be eligible for a price rise at the next price change window as his multiplier would have been removed meaning his current NTI would now be above the required threshold.
Q: What if a player has risen and fallen in the same GW?
This doesn't happen often, but we believe that the effect is to negate all the rules so you are effectively back to the start. Multipliers would not count, and your player would technically still be eligible for a further 3 rises (or drops).
Q: What about very low ownership players?
There is a belief that very low ownership players (perhaps below 1% owned in FPL) may have some slightly different rules, possibly to prevent too much price volatility. Low ownership players therefore may be slightly more susceptible to an unexpected price rise or drop, or may not rise or drop when predicted.
The advanced rules - flags & price protection
Q: When a player is unflagged, what happens to his NTI/NTO?
When a player goes from either red, orange or yellow flagged to clear, then his NTO or NTI at that time is reset to 0. That would mean that an unflagged player would have to breach the NTI/NTO threshold again to effect a price rise. If a player simply changes between flag colours his NTI/NTO tally is believed to be unaffected.