So now you are level 20. You got there by extensive candy farming, turning thousands of pidgeys, ratatas, caterpies and weedles into candy, feed the candy into their own kins, forcing them to evolve, and immediately smelt the evolved ones back to more candies.

This insane cycle continues as you sit mindless in a field of lures, rubbing Poke-pheromones all over your body, hauling in the big catch at a rate about 2 pokemons / minute, building up that critical mass of pidgey and ratatat to be set off with a lucky egg.

The farming has served you well. You are able to rack in insane amount of experiences, and quickly surpass your peers in levels. I know, I was there.

But the times are changing... the Pokemon have sensed your evil deeds, and began sending their strongest champions to defy you. No longer is it just a simple ratata cp10, it's a full fledged sewer abomination of 400 cp +, that defies all attempts of capture: blows your pokeballs off center, and even your well practiced curve-ball has no effect as it breaks the sturdiest of the balls at ease, spat berries at your feet. And be honest, would you use ultraballs for a mere rat?

You're running out of balls at a rapid pace, no longer can the 4 pokestops studded with lures satiate your mindless consumption of balls. The well oiled candy factory is breaking down.

__The Efficiency of Candy Farming__
As we all know experience gain constitute as one of the most important aspect of Pokemon Go!. When a trainer is leveled up, he has access to stronger pokemons which he then use in gym battles, and also access to higher level gears that would help in capturing rare pokemons for when they do appear.

The predominant way of farming experience is that of candy farming, turning low-tier pokemons into candies and feeding these candies back to force evolution, and collecting a huge boost of 500 exp per evolution. Just how efficient is candy farming? We're going to make the best case assumptions for candy farming, and calculate its effective exp/min.

Assuming you have a sick setup where the only pokemon that spawns near your lure are pidgeys, weedles, and others that only require 12 candies to evolve. Let's assume we're spawning all pidgeys.

Each evolution grants 500 exp.

It takes 12 candies to force an evolution.

Each pidgey provides 4 candies (with transfer).

It takes 3 pidgeys to force an evolution.

Thus, in addition to the 100 exp gained from a pidgey, each pidgey has an additional 500 / 3 exp benefit. All in all, a pidgey is worth 266 experience, and that is why pidgeys are so so so valuable in experience farming.

Assuming you are catching pidgeys at a rate of 2 / min, your effective rate of farm is 532 exp / min

This is an incredible rate, to put it in perspective I'm lvl 20 now and it takes 50000 experience to get to level 21. If we're doing a rate of 532 exp / min, in less than 100 minutes I would be lvl 21.

Now we all know that's some bs that never happens, so what's the catch?

For start, not all catch are good like pidgeys. Let's take other commonly found low level pokemons and measure their adjusted experience, taking evolution into account:

ratata: 25 candies needed to evolve, 6 ratatas are required to provide 24 ~ 25 candies. Thus, the evolution added exp for a ratata is 500 / 6 = 83. ratata is worth 183 experience

spearow: 50 candies needed to evolve, 12 spearows are needed. Thus, the evolution added exp for a spearow is 500 / 12 = 41. spearow is worth 141 experience

Imagine we have an equal spread of pidgey, ratata, and spearow.

Assuming you are catching a mix of pidgey, ratata, and spearows at a rate of 2 / min, your effective rate of farm is 400 exp / min

So that's a rule of thumb. If you're catching on average 2 pokemon for candy grinding every minute, you're looking at a pretty good rate of 400 exp / min. This is assuming you are catching all the time, without actually clicking to transfer, without actually watching the evolution animation, all of which takes more time.

__Why Candy Farming is Inefficient at High Levels__
Put it simply, candy farming doesn't work at higher levels because you cannot maintain the rate of 2 pokemons / minute. The issue is not pokemons are not appearing next to the lure, the problem is you run out of balls.

consider the following very generous assumptions:

--Assuming you are farming in a cluster of 4 pokestops.

--Assuming each pokestop gives you 10 balls a pop (let's convert a superball into 5 normal pokeballs)

--Then each pokestop is giving you balls at a rate of 2balls / min

--4 pokestops will give you balls at a rate of 8 balls / min

You are catching 2 pokemons every minute, which means you are using about 4 balls every pokemon. This is barely breaking even. If you use slightly more balls per pokemon, or not having enough pokestops nearby, you will run out of balls. To compensate this, you will need to travel to nearby pokestops, which invariably decrease your exp / min by actually not constantly catching pokemons.

With all these factors, if you are only catching one pokemon every minute, the actual farming rate is a mere 200 exp / min.

And don't get me started at how mindbogglingly boring it is.

__PokeStop Farming__
If you live or work in a densely populated area, say an university campus, you are blessed with tons of Pokestops.

As we know, each pokestop, when activated, yields 50 exp. If you are able to spin 4 signs / min, you are already looking at an experience gain of 200 exp / min, which is the farming rate if you are able to catch 1 pokemon / min.

So that's great news, as this way of farming does not degrade with level, the sign don't get harder to spin from when you're level 10 to level 20, where as a pokemon gets increasingly difficult to catch compared to when you're level 10.

As stated, a pokestop is 50 exp, so here are its equivalence roughly, in a rule-of-thumb way

-- a pidgeon is worth 5 pokestops

-- a ratata 3.5 pokestops

-- a fearow a mere 2.8 pokestops

So in your route of pokestop farming, you should take care to catch pidgeys still because they're worth many pokestops, but ratatas and fearows you should probably just pass.

__Pokestop farming offers the following advantages:__
1) It's healthy. You're on a bike, physically active. That's what pokeGo should be about, instead of sitting on a bench breaking your thumbs.

2) You get to encounter rare pokemons more often. In my night of riding, I was able to get an electribuzz, a growlith, a jigglypuff. Not that they're rare but I've just never had a chance to see them before.

3) You can STILL farm pidgeys. This is a huge benefit. You are traveling long distances, and you can pick and choose which pokemon to capture, and which one to ignore. You are not oblidged to catch the pokemon in front of your face all the time. If it's a high level zubat, forget about it, I'll find a cp40 pidgey soon enough anyways.

4) You can hatch eggs. You get 1 incubator. The conversion rate for km to exp is you'll gain 100 exp for every km traveled. If you're going fast enough and with multiple incubators this is an extra source of experience.

5) You get to make decisions on the fly, which is fun. Should I catch this pidgeon or should I travel to the next pokestop faster? Using the rule of thumb above, this can be fairly fun

6) Most importantly, really, it's just more fun... riding around, instead of watching the freaking same pidgeon evolving animation 10 times in a row, it's mind destroying.

7) Oh yeah it's free. no incense, no lure modules. you can put in an lucky egg if you feel like it though

__Conclusion__
I've taken upon myself to test this theory. Here is my route:

There are 3 missing pokestops to the right, so I in-layed them in the figure manually anyways.

**Thick red line**= my route

**Small red line**= pokestops used

Notice I sometime go slightly out of my way to reach a nearby pokestop, this is crucial. If you can spend an extra 5 seconds to get closer to a pokestop to be able to spin it, you should do so.

I start with this much experience:

I ended with this many, 30 minutes later:

On this trip, I also caught 4 pidgeys (166 *4 exp in addition to the capture exp) and 2 ratatas (83 * 2 exp in addition)

I didn't hatch an egg, but for sure I could've hatched a 2km egg for additional 200 exp

Put everything together:

(5945 + 166 * 2 + 83 * 2 + 200 ) 30 = 221 exp / min

Basically by going through enough pokestops, I was able to attain an exp gain at a rate comparable to capturing 1 pokemon every minute near a lure module.

I have not even tried to optimize my routes that well yet: On this route, the turn around time is bit less than 5 minutes, so I am still forced to stop once in awhile and catch a pokemon. Although this is not much of an issue given I can choose which pokemon to capture and am no longer obliged to catch everything.

In an earlier try when I was biking faster, I was able to clock 240 xp / min, but I didn't take good screenshots and keep track of how many pidgeys I got (i also found a jigglypuff which inflated my score)

If you want to do pidgey farming afterward, you're now very well equipted. I got so bored using normal pokeball I was using super ball the whole time and had to resort to the following:

I imagine now that I'm lvl 20, I can really push this idea easier because I'd be so rich in ultraballs I can catch anything.