Higher concentrations of DEET don't work better, they just last longer. ... Products with 10% DEET should repel bugs for about 2 hours, while those with concentrations of 20% to 30% last around 5. Limit exposure. Cover up with pants and long sleeves to minimize the amount of skin exposed to bugs (and bug sprays).

What strength of DEET should I use?

DEET is available in varying strengths up to 100%. Research shows that strengths greater than 50% do not provide substantially higher protection. Unless you are in areas with a large number of mosquitoes, repellents with 10% to 24% DEET should keep most mosquitoes away from your skin.

What DEET do I need?

So if you want to use DEET, skip the high concentrations. Opt for 7-to-10 percent if you only need a few hours of protection. If you need all-day protection, look for 20-30 percent DEET, ideally in a time-release formulation.