EPTIntroduction
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I have often seen questions referring to how one should transfer workers. Common arguments are:
#1: Transfer half of your workers
#2: Transfer all but 16 of your workers (so there is 2 workers per patch) and then send all new workers to your new base until you reach maximum saturation
#3: Leave maximum saturation on one base (24 workers) and only send new workers to the new expansion.
Most pros follow case #1 or #2 nearly exclusively and only follow #3 under rare circumstance.
#1: Transfer half of your workers
#2: Transfer all but 16 of your workers (so there is 2 workers per patch) and then send all new workers to your new base until you reach maximum saturation
#3: Leave maximum saturation on one base (24 workers) and only send new workers to the new expansion.
Most pros follow case #1 or #2 nearly exclusively and only follow #3 under rare circumstance.
Analysis
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One thing to consider is different maps have different mineral field placements and orientations. I will be basing my study on common mineral field placements (such that can be found on Xel Naga for example).
First off, lets define the amount of minerals one gains from various worker numbers on 1 base. One worker will bring in 40-45 minerals per minute depending on which patch it is mining. It takes 5 seconds (slightly more time actually, however, for simplicity’s sake, we will say 5 seconds) for it to bring in a batch of minerals (5 minerals). A base with 6 workers brings in about 260 minerals per minute, approximately 43 per worker. A base 16 workers will bring in 660 minerals every minute, 41 per worker. A base with 24 workers will bring about 800 minerals per minute, 33 minerals per worker. There are also some multibase numbers that I’ll talk about later.
One of the major things to consider about worker transfers is the amount of mining time lost during the transfer. In the long run of the game, the total mining time lost will be equal no matter if you follow 1, 2 or 3. If you send half of your workers (we’ll presume that is 12) at the same time, the mining loss time will be (T÷5) * 5 or just T * A (where T represents the time it takes to transfer and A represents the number of workers you are transferring).
This means that presuming a 25 second transfer time, if we send 8 workers, the lost mining time is worth about 200 minerals. We lose 8 minerals per second. On the other hand if we use method 3 and only send new workers, presuming we send 8 workers over the course of say 2 minutes, the total mining time lost is still worth 200 minerals, however, we aren’t losing those 200 minerals at once, we are losing those 200 minerals over the course of 2 minutes (or 1.6 minerals per second).
If we follow case #2 we will lose 200 minerals of mining time over the course of 25 seconds. However, once those probes have transferred, we are mining 960 minerals per minute (8 workers on the natural, 16 in the main) as opposed to 800 minerals per minute. It will take 1.25 minutes after the transfer to make up for the transfer.
If we build 24 workers and then follow case #1 we will lose 300 minerals of mining time over the course of 25 seconds (12 minerals per second). However, 2 bases operating with 12 workers each will receive an average of 1020 minerals per minute. It will take 1.36 minutes to make up for lost mining time (.11 minutes [6 seconds] longer recovery than case #2). However, once we have recovered, we receive a greater income (we receive 60 more minerals in case #1 than in case #2).
First off, lets define the amount of minerals one gains from various worker numbers on 1 base. One worker will bring in 40-45 minerals per minute depending on which patch it is mining. It takes 5 seconds (slightly more time actually, however, for simplicity’s sake, we will say 5 seconds) for it to bring in a batch of minerals (5 minerals). A base with 6 workers brings in about 260 minerals per minute, approximately 43 per worker. A base 16 workers will bring in 660 minerals every minute, 41 per worker. A base with 24 workers will bring about 800 minerals per minute, 33 minerals per worker. There are also some multibase numbers that I’ll talk about later.
One of the major things to consider about worker transfers is the amount of mining time lost during the transfer. In the long run of the game, the total mining time lost will be equal no matter if you follow 1, 2 or 3. If you send half of your workers (we’ll presume that is 12) at the same time, the mining loss time will be (T÷5) * 5 or just T * A (where T represents the time it takes to transfer and A represents the number of workers you are transferring).
This means that presuming a 25 second transfer time, if we send 8 workers, the lost mining time is worth about 200 minerals. We lose 8 minerals per second. On the other hand if we use method 3 and only send new workers, presuming we send 8 workers over the course of say 2 minutes, the total mining time lost is still worth 200 minerals, however, we aren’t losing those 200 minerals at once, we are losing those 200 minerals over the course of 2 minutes (or 1.6 minerals per second).
If we follow case #2 we will lose 200 minerals of mining time over the course of 25 seconds. However, once those probes have transferred, we are mining 960 minerals per minute (8 workers on the natural, 16 in the main) as opposed to 800 minerals per minute. It will take 1.25 minutes after the transfer to make up for the transfer.
If we build 24 workers and then follow case #1 we will lose 300 minerals of mining time over the course of 25 seconds (12 minerals per second). However, 2 bases operating with 12 workers each will receive an average of 1020 minerals per minute. It will take 1.36 minutes to make up for lost mining time (.11 minutes [6 seconds] longer recovery than case #2). However, once we have recovered, we receive a greater income (we receive 60 more minerals in case #1 than in case #2).
Conclusion
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So, what does all of this mean? There are only two types of transfer that you should make. Case #3, transferring no workers initially and rallying both bases to your natural (although I do recommend transferring workers eventually) and case #1 (transferring half of your workers).
The advantages to case #3 would be in a intense position or matchup in which you are not sure if you are safe. By not transferring your workers initially, you are making more money for 1.25 to 1.36 minutes until you lose money. That means 3 more zealots, 6 more pairs of lings or marines.
The advantages to case #1 is that you will make the most money in the long term. However, it will take 81 seconds to gain an advantage. After those 81 seconds you make 220 more minerals in the next minute than you would in case #3. EDIT: Make sure to see michaelhasanalias's argument, as he debates case #1 and suggests that case #2 is a more safe way to transfer workers.
Case #2 provides a 6 second short term advantage to #1 and a smaller long term advantage than #1 making it essentially useless. Since it still takes 1.25 minutes to recover, it isn’t good for very intense positions, and because it isn’t as good in the long run, there is no reason to use it in place of case #1. EDIT: Make sure to see michaelhasanalias's argument, as he debates case #1 and suggests that case #2 is a more safe way to transfer workers.
Late expansions
The later the expansion is, the less faults case #1 has. Since you don't gain an economic advantage from having more than 24 workers on a base due to exessive bouncing, and the more workers you have on a base increases how often worker bouncing occurs, the more workers you have, the less money you lose during the transfer under case #1. One of the things that this means, is if you are in a situation where you must follow case #3, you can transfer all but 24 workers without any economic damage to you.
Fast expansions
In fast expansions transferring is extremely strategic. There are different goals with transferring, and because of this I can't give you a true recommendation of which case to follow if you are fast expanding. Some things to remember though are:
a) Sometimes you transfer workers in an fe build to help defend early pressure
b) Earlier in the game minerals are more important, so the loss of transferring will hit you harder
c) There is less worker bouncing if there are less workers, so the incentive to transfer large amounts of workers is less than with normal or later expansions.
Vespene gas
ISTime pointed out some variations with gas that should be mentioned. Gas is highly build dependent and the way you need it changes the best worker transfer. Optimum reactions change if you expand without gas, expand with 1 gas at your main, expand with both gas, expand because you need more gas, etc, etc, etc.
Unfortunately I am unable to get as many hard numbers because it is so build dependent, however, here are some considerations with gas. If you take all of your gasses in your main and you also need to take the gasses at your natural while you transfer, it is better to transfer half of your workers + 6 so that you can instantaneously occupy your gas.
On the other hand, if you want to take a moderately timed third gas, then it is better to transfer half of your workers and then rally both bases to your natural for one production cycle, and then rally both bases back to their own mineral patches. You can then proceed to do that again if/when you need another gas.
The time that you need gas and expand greatly change how the optimum transfer for gas mining works as well.
Anyways, this isn't the *most* important issue, however I have seen different people say different things, I have seen different arguments for different worker transfers, however, I hadn’t seen any arguments with evidence to back it up. Hopefully this provides some insight, helps some people out, and provides you a slight macro edge.
Further thoughts
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This is just some more concepts and my own personal thoughts.
Which case I suggest
In my opinion #1 is the best way to transfer workers, there is no instance where you should be using #2, and #3 should be used rarely if you think you are going to die soon. EDIT: I may suggest #2 for now, I am going to run more tests later on, please see michaelhasanalias's posts.
[b]Worker bouncing/b]
If 2 workers are mining the same patch, there is a slight offset in mining times. As they both mine this offset grows (due to varying distances from the mineral patch to the base). A very over exaggerated example: Suppose it takes 4 seconds for a probe to collect minerals. The travel time from the patch to the base and back to the patch is 6 seconds. There is a 1 second offset that causes the probe mining time difference to become greater over time until both probes accidentally try to mine at the same time. Eventually one of the probes will mine that patch, and the other probe will go to a different mineral patch. This causes you to lose a small bit of mining time.
Notes
I have tested each case mentioned in this post in game to make sure the numbers align correctly. For me they have lined up, theoretically michaelhasanalias's numbers (which he does have more accurate constants than the ones I used [I must admit I may have over simplified several points]
Long term thoughts
There is also one other thing to consider. By transfering half of your workers instead of a smaller amount, then you will be able to mine out of your main base longer (meaning you will need to take a faster fourth, but you will be getting minerals from your main longer).
Zerg
The issue of transfering becomes much more complex with zerg. As a zerg player you will expand sooner (often times the expansion will be considered a fe of sorts) and you have the ability to make multiple workers at once (which will change the way you want to transfer a bit). I suggest reading the Fast expansion section of the conclusion which is the closest I come to a definitive answer for zerg.
I might do another post on zerg transferring and droning sometime if I get the chance and some thoughts of interest occur to me.
