On-chip decoupling capacitors (Decaps) are widely used to mitigate on-chip power supply noise. At and below 100nm on-chip decaps face leakage and area overhead problems associated with it and is estimated to increase with technology scaling. A recent work has proposed a gated decap structure to reduce leakage in decaps. Their work analyzes leakage saving obtained by implementing gated decap structure in a pipelined super scalar core. FPGAs on the otherhand face similar leakage problem associated with decaps in their un-mapped regions. We analyze here the leakage saving due to gated decap structure in FPGAs. With the on-chip gated decap structure we do uniform placement of decaps that achieves decap leakage savings of 7-60% with 39% on an average for various MCNC benchmarks mapped on to the FPGA device.