What is the expected gross profit margin for the company in the second quarter of 2021 
h will expand the capacity at UMC Fab 12A P6 in Taiwan Tainan Science Park through an innovative win-win partnership model with several leading global customers. The P6 expansion is scheduled for production in the second quarter of 2023 with total investment for the project earmarked at TWD100 billion.
In addition to UMC's previously announced 2021 capex of US$1.5 billion, the bulk of which is allocated toward equipment for the company's Fab 12A P5 sites, adjacent to P6. Total UMC investment in the Tainan Science Park will reach approximately TWD150 billion over the next three years. The P6 program is supported by a multiyear's product alignment between UMC and the involved customers that includes a loading protection mechanism that will ensure the P6 capacity is maintained at a healthy loading level.
We look forward to leveraging our number one worldwide foundry market position in multiple areas, such as 28-nanometer OLED driver IT production, so we may further strengthen UMC industry relevance and capture new market opportunities, in capturing new market opportunities down the road. Now, let's move on to the second quarter 2021 guidance. Our wafer shipments were increased by 2%. ASP in U.S. dollar were increased by 3% to 4%. However, the surging NT dollar headwind may potentially offset benefits on Q2 shipments increase and ASP growth.
Gross profit margin were a challenge 30%. Capacity utilization will be at 100%. Our 2021 cash-based capex will be budgeted at $2.3 billion, as Chi-Tung mentioned earlier. That conclude my comments. Thank you all for your attention. Now we are ready for question.
Questions and Answers:
Operator
Yes, thank you President Wang.[Operator Instructions] Our first question is coming from Randy Abrams from Credit Suisse. Go ahead please, Randy.
Randy Abrams -- Credit Suisse -- Analyst
Okay. Yes, thank you. Congratulations on the result and margin improvement. First question I want to ask on the capacity expansion. Could you discuss the amount of capacity for the Fab 12A Phase 5 with the capex raise? And also how much capacity is planned for Phase 6 with the TWD100 billion plan and if there is a framework for total capex, if you also expect any spending to continue in China or other facilities. If there is a view the current year's spend may continue around this level for the next couple of years?
Chi-Tung Liu -- Chief Financial Officer
So Randy, for P6 alone, the total capex is around TWD100 billion. And it's likely -- the spending is likely to spread out through over the next three years, so, starting from latter part of this year, bulk of that in 2022 and also nearly one-third in 2023. So that will be the key part of our capex over the next three years.
And for the original budget of TWD1.5 billion, the bulk of that will go to the 10,000 wafer 28-nanometer capacity per month at P5. That's already ongoing. And we are seeing the contribution earlier, maybe as early as next year
For Xiamen, we are also already reaching to the target -- closing to the target level of 25,000, wafer per month. And as you recall, it was about, 17,000, 18,000 wafer by -- about the same time last year. But through the extension, now it's close to the focus of the capacity right now. So maybe Jason, you want to add to few more?
Jason Wang -- Director and President
I think the other data point is for the Tainan facility, after the P5, will be about 90,000 wafer capacity, total for the Tainan site, the 12A. And by adding the P6, we'll be on top of the 90,000. So we are approaching about 120,000 [Speech Overlap].
Randy Abrams -- Credit Suisse -- Analyst
Okay. So, to clarify, it's 90K to 0K P5, P6 is 20K. So that brings it to 120. Okay. And the second question, it gets back to the mechanism and this new expansion schedule. If you could talk on how the pricing and margins as you expand and grow the business with the new capacity, how would that impact relative to your current margins where they're getting to 30%. And if you could give an updated view that the depreciation where it was originally on that kind of nice down tren
h will expand the capacity at UMC Fab 12A P6 in Taiwan Tainan Science Park through an innovative win-win partnership model with several leading global customers. The P6 expansion is scheduled for production in the second quarter of 2023 with total investment for the project earmarked at TWD100 billion.
In addition to UMC's previously announced 2021 capex of US$1.5 billion, the bulk of which is allocated toward equipment for the company's Fab 12A P5 sites, adjacent to P6. Total UMC investment in the Tainan Science Park will reach approximately TWD150 billion over the next three years. The P6 program is supported by a multiyear's product alignment between UMC and the involved customers that includes a loading protection mechanism that will ensure the P6 capacity is maintained at a healthy loading level.
We look forward to leveraging our number one worldwide foundry market position in multiple areas, such as 28-nanometer OLED driver IT production, so we may further strengthen UMC industry relevance and capture new market opportunities, in capturing new market opportunities down the road. Now, let's move on to the second quarter 2021 guidance. Our wafer shipments were increased by 2%. ASP in U.S. dollar were increased by 3% to 4%. However, the surging NT dollar headwind may potentially offset benefits on Q2 shipments increase and ASP growth.
Gross profit margin were a challenge 30%. Capacity utilization will be at 100%. Our 2021 cash-based capex will be budgeted at $2.3 billion, as Chi-Tung mentioned earlier. That conclude my comments. Thank you all for your attention. Now we are ready for question.
Questions and Answers:
Operator
Yes, thank you President Wang.[Operator Instructions] Our first question is coming from Randy Abrams from Credit Suisse. Go ahead please, Randy.
Randy Abrams -- Credit Suisse -- Analyst
Okay. Yes, thank you. Congratulations on the result and margin improvement. First question I want to ask on the capacity expansion. Could you discuss the amount of capacity for the Fab 12A Phase 5 with the capex raise? And also how much capacity is planned for Phase 6 with the TWD100 billion plan and if there is a framework for total capex, if you also expect any spending to continue in China or other facilities. If there is a view the current year's spend may continue around this level for the next couple of years?
 Chi-Tung Liu -- Chief Financial Officer
So Randy, for P6 alone, the total capex is around TWD100 billion. And it's likely -- the spending is likely to spread out through over the next three years, so, starting from latter part of this year, bulk of that in 2022 and also nearly one-third in 2023. So that will be the key part of our capex over the next three years.
And for the original budget of TWD1.5 billion, the bulk of that will go to the 10,000 wafer 28-nanometer capacity per month at P5. That's already ongoing. And we are seeing the contribution earlier, maybe as early as next year
For Xiamen, we are also already reaching to the target -- closing to the target level of 25,000, wafer per month. And as you recall, it was about, 17,000, 18,000 wafer by -- about the same time last year. But through the extension, now it's close to the focus of the capacity right now. So maybe Jason, you want to add to few more?
Jason Wang -- Director and President
I think the other data point is for the Tainan facility, after the P5, will be about 90,000 wafer capacity, total for the Tainan site, the 12A. And by adding the P6, we'll be on top of the 90,000. So we are approaching about 120,000 [Speech Overlap].
Randy Abrams -- Credit Suisse -- Analyst
Okay. So, to clarify, it's 90K to 0K P5, P6 is 20K. So that brings it to 120. Okay. And the second question, it gets back to the mechanism and this new expansion schedule. If you could talk on how the pricing and margins as you expand and grow the business with the new capacity, how would that impact relative to your current margins where they're getting to 30%. And if you could give an updated view that the depreciation where it was originally on that kind of nice down tren