The owner of an online vintage store on P.E.I. is worried about how increased rates for parcels are going to affect her business.

Rates are going up on both domestic and international parcel shipping on Monday.

Katharine MacDonald runs the online vintage store Milk and Amber, and the majority of her costs are shipping. She's had to work hard to keep prices down.

"The ladies actually at the post office will take apart my thing, and they'll be like, can we shave off a little bit of this cardboard so that it's 12 grams less," said MacDonald.

Shaving costs will be that much more important come Monday, with domestic rates going up an average of four per cent, and international rates an average of two per cent.

Math working against online businesses

Katherine MacDonald with eyeglasses

MacDonald would like to deal more in items like vintage eyeglass frames, which are small and light, and therefore easy to ship. (CBC)

Canada Post does offer a small business program that can provide some savings, but MacDonald said it doesn't help her business much.

She's worried the latest increase could turn customers off.

"When people kind of do the math, they might just look at all their options," she said.

"If online shopping becomes too risky then it will affect people who primarily do their business online."

MacDonald said she may have to increase her prices or simply accept lower profits from her business.

"A bigger item that I can sell for more, it's probably going to also be harder to ship," she said.

"If people are more reluctant to buy it, I just won't put more expensive items on my shop and therefore I might make less money."

A spokesperson for Canada Post said inflation has forced the postal rate increase.