The main question is how big is 7nm Vega package. If the package is the same as 14nm Vega’s, then comparing them is easy. At 4Gamer we found a picture of Lisa Su presenting 7nm EPYC CPU with 7nm Vega in both hands. This gave us the opportunity to measure SP3 package and compare sizes. Since we know SP3 package is 58.5 x 75.4 mm, we can quickly conclude that 7nm Vega package is roughly ~47.8mm on each side. This means the package is likely identical to 14nm Vega (47.5mm). From here we compare pixel density and the rest is simple.
It’s worth reminding you that 14nm Vega dimensions are officially 486 mm2, while measurements from the press gave it a 510-ish mm2 die size. We are going to include this margin of error into our quick calculations and we end up with 285-298 mm2 7nm Vega die size.
That said, 7nm Vega is likely under 300 mm2.