We present a systematic study of the impact of strain on off-state leakage current, using experimental data and ab-initio calculations. We developed new models to account for the impact of strain on band-to-band tunneling and trap-assisted tunneling in silicon. We observe that the strain can dramatically increase the leakage current, depending on the type of tunneling involved. We predict that 1% compressive strain can increase the band-to-band tunneling and Shockley Read Hall leakage currents by over 5 and 3 times, respectively.