The Parks Department is hitting the MTA with a massive bill because of a formula that requires dozens of expensive saplings to be planted for each tree knocked down.

The agency is charging the MTA a staggering $520,550 to remove and replant 16 trees — or nearly $33,000 a tree, according to a procurement.

Parks officials say local law requires that they replace each tree’s total square inches.

For instance, replacing a maple tree with a 24-inch diameter would require planting up to 46 young trees, at a cost of $1450 per sapling.

Parks officials say they have to replace each tree’s total square inches, so replacing a 3-foot-tall tree requires planting up to 46 young trees, at a cost of $1450 per sapling.

The MTA needs the trees taken down to build a temporary ramp at the RFK/Triborough Bridge.

“It certainly is a waste of money,” said MTA board member Jonathan Ballan, who voted against the procurement the agency approved on Monday.