As we technique Pokémon GO’s third anniversary, many kind of travelers are still chasing their Youngster and also Fisherman medals. These objectives focus on the height and also weight of wild Pokémon – a component of each Pokémon’s distinctive identity that has no other well-known effect in-game thus much.

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While pondering these Pokémon features many kind of months earlier, the Silph Research Group set out to uncover how Pokémon height and also weight are determined.

After weighing and measuring nearly 50,000 Pokémon in a massive research, we found wormonarchs behind the elevation and also weight system. This basic however elegant version explains:

How height and also weight are generatedHow the 2 worths are interlinkedHow they persist throughout evolutionsThe mechanics behind Pokémon size appraisalsThe odds of receiving a tiny Rattata or big Magikarp

Due to the modern launch of numerous amazing new features (favor PvP, the weather mechanism, Community Days, and also a full year of events), these findings were never before publimelted. Fortunately, this discovery will finally watch the light of day! We’re proud to be able to say that the efforts of dedicated Silph Researchers both new and old will cause another entry right into the ever-prospering canon of resolved mysteries of Pokémon GO. Without any even more delay – let’s dive in!

The Data

The data for this research was gathered in four segments:

1>2,000MagikarpExplore elevation and also weight in relation to various other Pokémon attributesHeight and also weight
227,000Typical PokémonSpeed up information gathering
310,000Species via mean elevation ≥ 1.5 mInvestigate how rounding affects distribution
48,500Special casesNarrow dvery own precise appraisal boundariesFull appraisal

As the third and also fourth segment just clarified results from the earlier information sets, an exemption was made to enable historic data from January 2017 forward. Data from 2016 was excluded to encertain the results weren’t biased by the early on evolution bug¹.

Generating Height and Weight

With this dataset, Silph Scientists were able to reverse engineer the strategy provided to generate height and also weight. Starting via the most basic possible distribution (unicreate between 2 values) the information was checked to see if it fit a variety of feasible distributions. Each version was rejected if it didn’t fit the information. This process was repetitive several times until the hidden methodology used to generate a Pokémon’s elevation and also weight was unextended.


A few straightforward steps determine the height of a Pokémon.

Next, random height is multiplied by the height worth noted in the Pokémon’s Pokédex enattempt (or more specifically the game master file, which has complete, unrounded values) in order to acquire the final elevation of the Pokémon. Simple as that!Weight

Determining the weight variable involves a pair additional procedures. The first step in generating weight is identical to generating elevation. A random number is drawn from a normal circulation through a mean of 1 and a conventional deviation of 1/8. We call this number random weight. Next off, random weight is multiplied by random height squared to obtain an intermediate variable. Let’s contact this variable intermediate weight. Mathematically this looks like:

intermediate weight = random weight * random height2

Finally, intermediate weight is multiplied by the weight worth detailed in the Pokédex (or game grasp file) to obtain the final weight of the Pokémon.


Generating the weight in this means has actually a pair of various effects. First, the weight of a Pokémon is even more variable than its height. In fact, it has actually a traditional deviation nearly 2.8 times that of elevation. This is why even more Pokémon have actually an XS or XL presented on their weight in the Pokémon appraisal display than elevation. Secondly, bereason the random elevation variable is used to calculate the last weight of the Pokémon, the height and also weight of a Pokémon are well-correlated. You wouldn’t want a Snorlax that is in the height 1% of elevation, however the bottom 1% of weight! This algorithm keeps that from happening, but also offers some nice varicapability.

Here’s a plot to help visualize this partnership. The elevation and also weight of each Pokémon have been normalized by its mean species elevation and weight in order to correctly compare them. This is basically a plot of the random height and also intermediate weight variables.


Normalized height and also weight distribution for all Pokémon species

Evolutions and Rounding

Now that we’ve lassist out a basic frame for generating elevation and weight, predicting the brand-new worths after evolving your Pokémon is basic. Simply divide the height and weight worths displayed in the Pokémon appraisal display by the expect values shown in the Pokédex entry for that species, and also then multiply by the new intend for the advanced create. We have the right to do this because the random elevation and also random weight values don’t readjust when a Pokémon is evolved.

Now, if you were to actually attempt this on a Pokémon, you could find that the values don’t match perfectly. This is bereason of rounding errors. We were able to show this thanks to a very lucky triplet of the same Pidgeys (nicknamed Harpo, Groucho, and Chico), provided to us by Silph Scientist Constituent (DonLothario). Here are their height and also weight values prior to and after advancement.

Harpo0.29 m / 2 kg1.06 m / 33.39 kg1.44 m / 43.97 kg
Groucho0.29 m / 2 kg1.06 m / 33.36 kg1.45 m / 43.93 kg
Chico0.29 m / 2 kg1.05 m / 33.4 kg1.43 m / 43.97 kg

For this scenario to be true, each of the Pidgey’s elevation worths need to be saved to a higher degree of accuracy than shown on the appraisal display. The stored weight need to be in between 1.995 kg and also 2.005 kg while the elevation is in between 0.285 m and also 0.295 m.


Knowing that displayed worths are rounded is valuable for the last component of the study that investigated the limits of the appraisal device. Tright here are three independent appraisals which are either shown on screen or have the right to be checked by means of the appraisal attribute. They are:

The XS and also XL shown beside a Pokémon’s elevation.The XS and XL shown beside a Pokémon’s weight.The dimension appraisal given by your team leader.

The XL and also XS displayed next to a Pokémon’s height or weight on its information display are established by the deviation from the suppose height or weight of that species. Anything even more than 2 conventional deviations above the suppose height or weight is XL, and also anypoint much less than 2 standard deviations below the intend height or weight is XS.

However, the dimension appraisal from your team leader is various from the XS and XL tags. It deserve to be predicted by adding together the random height and also intermediate weight variables debated formerly. We can then compare this value to the borders presented in the table listed below.

Possible appraisalsSum of random elevation and intermediate weight
Tinier or the tiniest or so tinyLess than 1.5
Below average in dimension or a small tiny or fairly cuteBetween 1.5 and also 1.75
Above average in dimension or BIG one or rather sizeableBetween 2.25 and also 2.5
 Colossal or just HUGE or giganticGreater than 2.5

All of this is ideal portrayed in a graph aacquire.


Appraisal boundaries added to the circulation of elevation and also weight

The XS and XL marmonarchs displayed on a Pokémon’s indevelopment display screen are stood for as horizontal or vertical lines in the plot on the left. Interestingly, bereason of rounding, tright here are numerous height and weight worths of certain Pokémon species that deserve to display the specific same height/weight on their indevelopment web page, however differ in their XS or XL symbol from one an additional. The size appraisals from each of the team leaders are diagonal lines shown in the appropriate plot.

Overlaying these limits, we have the right to see that several combinations are feasible. For instance, a Pokémon could be colossal but not XL. You have the right to additionally plainly check out that the XL and also XS are much more prevalent for weight than elevation.


All dimension appraisals in Pokémon Go overlaid on one graph

Fisherman and also Youngster Medals

Finally, we would be remiss out on if we left out the Fisherman and Youngster medal boundaries from a conversation on elevation and weight! These boundaries are found at around 2.5 typical deviations amethod from the suppose. This equals a “tiny Rattata” being any kind of that are lighter than 2.41 kg and a “large Magikarp” being any that are heavier than 13.13 kg. These worths have actually been reported by various other travelers on The Silph Road, and also our information confirms them. Simulating 10,000,000 height and also weight values in R based on the algorithm explained above, we were able to identify that the probcapability for gaining a tiny Rattata³ is 11.7% and for huge Magikarp it’s 14.6%. These borders are displayed in the number below:


Parting Words

We hope that you’ve took pleasure in this peek behind the curtain of the height and weight device of Pokémon GO! As of currently, elevation and also weight don’t affect your Pokémon’s battle readiness or movesets, yet ssuggest carry out a more realistic backdrop for the game. Hopefully, this post helps you to determine if you’ve captured yourself a once-in-a-lifetime Pokémon. We’ll see you on the road, travelers!

Notable Researchers

The Silph Research Group would certainly favor to give a unique shoutout to longtime Scientist, DrThod who single-handedly cracked the formula behind Height and Weight. Without his tough job-related, all these discoveries would certainly not have been feasible.


¹ In the early days of Pokémon GO it seemed that nearly all Pokémon that were evolved turned out to be XS in weight. This was a pest in the calculation of new weight and also elevation after the evolution. It seems that Niantic used the intend elevation of the evolved species and also the suppose weight of the unadvanced form once calculating the brand-new advanced worths. All at an early stage Eeveelutions, therefore, appear to be XS with worths exterior our plot while some Pokémon choose Venomoth turned out XL as their pre-advancement species was heavier.

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² Based on our information, a normal circulation was the ideal fitting and most parsimonious circulation based on the Akaike Information Criterion. However before, tright here was an exciting situation that surchallenged during the July Community Day wbelow a traveler regulated to capture a Squirtle weighing 0.01kg. Using simulations in R, Silph Scientists tried to reproduce the previously mentioned Squirtle using the normal distribution and the transdevelopment outlined above yet were uneffective in over 500,000,000 trials. This may show that the distribution for weight has actually slightly heavier tails than a conventional normal distribution (e.g. t-distribution), however the current dataset might not validate this hypothesis.

³ Alolan Rattata has actually a slightly better average weight, yet the required weight of 2.41 remains constant for either develop. This suggests that the Alolan develop is less most likely than its equivalent to be “tiny.”