How much DMSO do I add to PCR?

For a typical PCR experiment, ideally 3-10% DMSO should be added to PCR, which assists in the denaturing of templates with high GC concentrations. The exact concentration of DMSO in a reaction depends on the GC content, reaction type, and quality of DMSO. For more optimization, DMSO should be varied in 2% increments. If high DMSO concentration is used, the annealing temperature must be lowered. DMSO decreases melting point of the primers. 10% DMSO decreases annealing temperature by 5.5-6.0 degrees celsius.