Denying women full participation in the global economy is costly.McKinsey & Co. has now calculated by just how much.

Full gender equality would add 26 percent, or $28 trillion, to globalgross domestic product in 2025, according to a new report by the consulting firm’s research and economics arm.

While capturing that potential may not be realistic in the short term, boosting women’s equality at the same rate as the fastest-improving nation in a region — bringing Bangladesh to the level of Singapore, for instance — would increase annual GDP by $12 trillion in 2025, the study said.