Canadians shopping for new coats to block the winter chill should not base their decisions on temperature rating systems alone, according to retailers who note factors such as wind force and stitching should also be considered.

Josh Girman of Mountain Equipment Co-op says the temperature ratings — which are used by manufacturers including L.L. Bean and The North Face — don't account for important variables.

"What are you wearing underneath the jacket? How windy is it outside? How much did you eat today?" he asks, noting MEC parkas do not carry the ratings. "All of these things can come into play in terms of how warm you'll be in a jacket."

Girman said customers should consider the fill power of down (fluffiness or loft) and the quality of the stitching when purchasing a coat.

"If you've got three different coats by the company with three different ratings — you can look at that and see warm, warmer, warmest," he said. "But by no means should you expect that the specific number they're giving you in terms of a temperature rating is going to be accurate."

Jomo Winter, a Winnipeg-based sales representative at Cabella's, also suggests the jacket ratings are imperfect, saying the degree of warmth a jacket provides is dependent on wind chill and what a person is wearing underneath the coat. He also notes the amount of activity by a wearer affects the overall effectiveness.

"If you're just standing still, you cut that rating in half," he said.

But researcher Elizabeth McCullough of Kansas State University says the rating system can be useful for consumers. McCullough is chairing a committee for the American Society for Testing and Materials to create a standardized rating system for winter clothing.

"We think standardizing temperature ratings is important so consumers can compare products from a variety of manufacturers," she said.

"We are trying to give consumers information that will help them select the right amount of insulation, keeping them safe."