Total workforce availability varies greatly across the top offshore outsourcing locations.  China and India are in a league of their own with workforces of 800 million and 500 million respectively. Granted, the over whelming majority of these resources would not be employable in technology or business process outsourcing operations, but they provide a massive reservoir to draw upon.

Top Outsourcing Locations by Workforce - Figure 1

Source: CIA World Factbook (2008)

Following India and China, the next biggest workforce is a little over 100 million in Indonesia.  The next few largest (Brazil, Russia, Pakistan) are scattered across several regions of the globe.

The Eastern European locations typically have smaller workforces.  Ukraine is the largest with about 22 million and Poland comes in second with 17 million.  The remaining European locations (Romainia, Czech Republic,  Hungary and Bulgaria) all have workforces under 10 million.