StarCraft2: Easy way to calculate number of harvesters

It sounds like your problem is less, "I need a counter" and more "How could I have known?"

First off, you said you scouted him but he proxy'd his Barracks (hid it outside of his base). Let's go over the ways you could have still seen this coming:

• Usually not seeing a Barracks is a good sign he's Proxying.
• Watching for a very early Vespean Refinery is usually a sign of some sort of early Marauder/Reaper play
• Finally, many top Protoss players default into 1 Gate -> Cybernetics Core to set themselves up to stop this.

What else could you have done?

Some guide will suggest skipping that first Zealot, but if you can squeeze him out (Zealot has a 33 sec build time compared to the Cybernetics Core's 60) he serves as a good distraction to keep the reapers off your probes.

Make sure to save some extra chrono boosts to boost out a Stalker. While early game you should be using these on Probes, once you start building the Cybernetics Core stop using them and save them for the Stalker.

Another problem you had was a Bunker slipping in. There are a couple ways to stop this, but most prominently walling off your ramp. You can do this with your Gateway/Cybernetics Core, or leave space and place that first Zealot there. Alternatively, you can build an extra pylon closing off that small space with plans to kill it later.

Once he does start building the Bunker, you can use either your Stalker or even your Probes to try and kill it during production (or even better the SCV building it). The follow up will usually be a large number of Marauders so you can either push out Zealots to deal with this (its unlikely he'll have concussive shell this early), or a Sentry. With the Sentry you'll want to use force field at the bottom of your ramp to keep him from moving up and gaining sight. You can then use your Stalker to prevent Reapers from giving sight and to target the helpless Marauders.

In any case you should consider your next move. Are you going to go Robo? get out an early Immortal. Or do you want to throw up 2-3 Gate and out produce him (as he's seriously cut production).

One of the things you'll notice is that as you continue to play, the time it takes you to get out that first stalker will rapidly decrease. A Reaper rush really trades on the opponent not seeing it, and not being very experienced.

So there is no good answer to this question, or it would already appear in the larger build order questions on this site. Unlike the early game (which is well defined) mid to late game doesn't have an easy answer, and anyone who gives you a BO past 20 is a snake oil sales man.

Even in the Zerg question you linked the answer was: What ever feels best.

Let's look at some of the basic Protoss builds and how they progress:

4 Gate

Usually this build is very all-in, and you're banking on winning early. However, if you do enough economic damage with a 4 Gate, but don't win you can still be at an advantage. At this point if you pressure more you're going to end up against a higher tech opposing force and probably lose, so you can expand here and maybe add on a Robo or two more Gateways.

3 Gate

One of the great things people like to do with 3 Gate is provide pressure so that they can expand. This sets them up with a nice little force as they transition into the mid game. Once expanding there are some people who like to progress to 5 Gate + Robo, or 3 Gate + Double Robo, or even (recently) 3 Gate + Double Starport. There is even a nice 4 Gate + Robo to provide pressure so that Protoss can take a third expansion.

You probably notice a number of trends between these two builds, even though I picked two builds that could not be more different there were a number of important ideas:

• Your Production must be proportional to your Income. If you have less production than your income you need to have a plan for it (eg. setting up to expand). If you have more production than your income you need to be aggressive
• Don't over commit. When you're ahead, your number 1 priority should be to get more ahead (ie. expand)
• While you always need to tech (ie. Red Queen Hypothesis) teching takes time, so don't forget that in your calculations.

Now you'll notice that a lot of what's being discussed is Income vs Production and there are a couple tools you can use to help you out:

• Protoss Calculator
• Terran Calculator
• Zerg Calculator

Remember: To get good at Starcraft you need to get good at Execution and Decision Making, not get good at following a road map.