The circumference was given in the manga at 220,000 in contrast to Earth's 40,000, making Toriko world over 5x larger in diameter.
Keep in mind that this is only the ratio for diameter and circumference, the ratio increases by magnitudes when talking about surface area and volume. (ex. Neptune's circumference is only around 4x that of Earth but its surface area is around 15x greater and its volume is over 50 Earths, Jupiter's circumference being 11x greater than Earth could comfortably house over 1000 Earths inside of it.
Toriko World's Human World surface area >>> Earth surface area.
No offence but if you really need to see 50-60 pages of equations to prove a simple geometry problem then you should go back to the 7th grade.