Island Planning For all the island planners, whether you use it for raid defences, farming or simply to build some awesome structures, one thing worth knowing is the cost of expanding your island. I got these figures through expansions 1-8, so if the rate changes at larger island sizes, this information may be incorrect. Per expansion after the second expansion, the increase in cost is 40% of the previous expansion (x 1.4 multiplier), floored to the nearest integer. This equates to the cost for each expansion as: 0 gems 1,800 gems 2,520 gems 3,528 gems 4,939 gems 6,914 gems 9,679 gems 13,550 gems 18,970 gems 26,558 gems 37,181 gems 52,053 gems 72,874 gems 102,023 gems 142,832 gems 199,964 gems 279,949 gems 391,928 gems 548,699 gems 768,178 gems 1,075,449 gems 1,505,628 gems 2,107,879 gems 2,951,030 gems Therefore if you're planning on having a 3x3 area (requiring 8 expansions), the total cost to expand the island is 42,930 gems. In comparison, to build a larger base and go from 3x3 to 5x5 (requiring 16 further expansions), the extra expansion cost is 10,281,195 gems.