As we approach Pokémon GO’s third anniversary, many type of travelers are still chasing their Youngster and Fisherman medals. These missions emphasis on the height and weight of wild Pokémon – a part of each Pokémon’s unique identity that has no other recognized impact in-game thus far.

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While pondering these Pokémon characteristics many months back, the Silph Research Group collection out to uncover how Pokémon elevation and also weight are established.

After weighing and also measuring nearly 50,000 Pokémon in a large research, we found workings behind the height and also weight system. This simple 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 substantial Magikarp

Due to the modern launch of numerous interesting new features (prefer PvP, the weather mechanism, Community Days, and also a full year of events), these findings were never before published. Fortunately, this discovery will certainly finally watch the light of day! We’re proud to be able to say that the initiatives of dedicated Silph Researchers both brand-new and also old will certainly lead to another entry into the ever-thriving canon of fixed mysteries of Pokémon GO. Without any additionally delay – let’s dive in!

The Data

The data for this study was gathered in 4 segments:

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

As the third and also fourth segment only clarified results from the previously data sets, an exemption was made to allow historic data from January 2017 forward. Documents from 2016 was excluded to ensure the outcomes weren’t biased by the at an early stage evolution bug¹.

Generating Height and also Weight

With this datacollection, Silph Scientists were able to reverse engineer the technique provided to geneprice height and also weight. Starting via the easiest possible circulation (unidevelop between two values) the information was checked to watch if it fit a variety of possible distributions. Each design was rejected if it didn’t fit the data. This procedure was repeated numerous times until the covert methodology provided to geneprice a Pokémon’s height and also weight was unspanned.


A few straightforward steps determine the height of a Pokémon.

Next, random elevation is multiplied by the elevation value provided in the Pokémon’s Pokédex entry (or even more especially the game master file, which includes complete, unrounded values) in order to gain the last height of the Pokémon. Simple as that!Weight

Determining the weight variable involves a couple additional steps. The first action in generating weight is similar to generating elevation. A random number is drawn from a normal circulation via a suppose of 1 and also a typical deviation of 1/8. We contact this number random weight. Next, random weight is multiplied by random height squared to get an intermediate variable. Let’s speak to this variable intermediate weight. Mathematically this looks like:

intermediate weight = random weight * random height2

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


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

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


Normalized height and also weight distribution for all Pokémon species

Evolutions and also Rounding

Now that we’ve lhelp out a straightforward frame for generating elevation and also weight, predicting the brand-new values after evolving your Pokémon is basic. Simply divide the height and weight worths presented in the Pokémon appraisal display by the expect values presented in the Pokédex enattempt for that species, and also then multiply by the brand-new mean for the evolved develop. We have the right to carry out this bereason the random elevation and random weight worths don’t change when a Pokémon is evolved.

Now, if you were to actually attempt this on a Pokémon, you could discover that the worths don’t match perfectly. This is because of rounding errors. We were able to present this thanks to a very lucky triplet of similar Pidgeys (nickcalled Harpo, Groucho, and also Chico), offered to us by Silph Scientist Constituent (DonLothario). Here are their elevation and also weight values prior to and also 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 values should be saved to a greater level of accuracy than presented on the appraisal display screen. The stored weight must be between 1.995 kg and 2.005 kg while the elevation is between 0.285 m and 0.295 m.


Knowing that presented values are rounded is helpful for the last part of the research that investigated the limits of the appraisal device. There are 3 independent appraisals which are either presented on screen or deserve to be checked by means of the appraisal attribute. They are:

The XS and also XL shown beside a Pokémon’s height.The XS and XL presented alongside a Pokémon’s weight.The size appraisal given by your team leader.

The XL and also XS shown beside a Pokémon’s height or weight on its information display screen are identified by the deviation from the suppose height or weight of that species. Anything even more than 2 standard deviations over the expect elevation or weight is XL, and also anything less than 2 traditional deviations listed below the suppose height or weight is XS.

However before, the dimension appraisal from your team leader is different from the XS and XL tags. It have the right to be predicted by including together the random height and intermediate weight variables questioned formerly. We have the right to then compare this value to the boundaries displayed in the table below.

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

All of this is ideal portrayed in a graph again.


Appraisal borders included to the distribution of height and weight

The XS and also XL marmajesties displayed on a Pokémon’s indevelopment display screen are represented as horizontal or vertical lines in the plot on the left. Interestingly, bereason of rounding, tbelow are several height and weight values of specific Pokémon species that deserve to display screen the exact same height/weight on their information web page, but differ in their XS or XL symbol from one another. The size appraisals from each of the team leaders are diagonal lines displayed in the appropriate plot.

Overlaying these boundaries, we have the right to see that numerous combinations are possible. For example, a Pokémon could be colossal but not XL. You can additionally clearly check out that the XL and XS are much more common for weight than height.


All dimension appraisals in Pokémon Go overlhelp on one graph

Fishermale and Youngster Medals

Finally, we would be remiss out on if we left out the Fishermale and also Youngster medal boundaries from a conversation on elevation and weight! These boundaries are discovered at around 2.5 typical deviations ameans from the suppose. This equates to a “tiny Rattata” being any kind of that are lighter than 2.41 kg and a “big Magikarp” being any kind of that are heavier than 13.13 kg. These values have actually been reported by other travelers on The Silph Roadway, and our information confirms them. Simulating 10,000,000 elevation and weight values in R based on the algorithm defined above, we were able to recognize that the probability for obtaining a tiny Rattata³ is 11.7% and for large Magikarp it’s 14.6%. These limits are presented in the number below:


Parting Words

We hope that you’ve appreciated this peek behind the curtain of the elevation and weight mechanism of Pokémon GO! As of now, height and weight don’t influence your Pokémon’s fight readiness or movesets, but simply provide a much more realistic backdrop for the game. Hopetotally, this write-up helps you to identify if you’ve captured yourself a once-in-a-life time Pokémon. We’ll view you on the road, travelers!

Notable Researchers

The Silph Research Group would certainly favor to provide a distinct shoutout to longtime Scientist, DrThod that single-handedly cracked the formula behind Height and Weight. Without his hard work, all these discoveries would certainly not have been feasible.


¹ In the at an early stage days of Pokémon GO it appeared that almost all Pokémon that were advanced turned out to be XS in weight. This was an insect in the calculation of brand-new weight and height after the development. It seems that Niantic provided the intend elevation of the progressed species and the expect weight of the undeveloped develop when calculating the new progressed values. All at an early stage Eeveelutions, therefore, show up to be XS with values exterior our plot while some Pokémon favor 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 finest fitting and many parsimonious circulation based on the Akaike Information Criterion. However before, tbelow was an amazing situation that surchallenged during the July Community Day wbelow a traveler regulated to catch a Squirtle weighing 0.01kg. Using simulations in R, Silph Scientists tried to recreate the aforementioned Squirtle utilizing the normal distribution and also the transformation outlined above however were uneffective in over 500,000,000 trials. This may show that the circulation for weight has actually slightly heavier tails than a typical normal distribution (e.g. t-distribution), yet the present dataset could not validate this hypothesis.

³ Alolan Rattata has actually a slightly greater average weight, but the compelled weight of 2.41 remains constant for either develop. This indicates that the Alolan develop is less likely than its equivalent to be “tiny.”