TORONTO -- Canadians planning to tie the knot expect to spend an average of $15,000 on their big day, but many don't think they'll be able to foot the entire bill, according to a new study.

The BMO InvestorLine survey of 500 adults revealed that nearly 40 per cent of respondents believe their ideal wedding is out of reach.

Canadians surveyed expect to cover 60 per cent of the costs associated with their wedding by drawing on investments or other savings. For the remaining costs, they predict they'll rely on parents and gifts from friends.

BMO InvestorLine CEO Julie Barker-Merz said she was "quite shocked" at how little respondents would allocate for a potential wedding.

"I think retirement falls into that category where people will typically underestimate what they're going to need to spend and then they get surprised. And I think in this case what this study showed was a very similar pattern of behaviour," she said in a phone interview Wednesday.

Barker-Merz was also surprised by respondents who said they'd rely on credit cards and/or lines of credit.

"Typically, lines of credit and credit cards when it comes to weddings is for those unforeseens, things you didn't plan for and anticipate. The fact that the people surveyed have that as part of their plan just points to the need of really getting smart on how to plan, how to budget, how to save money and plan for what you can afford."

For her spring 2010 wedding in Edmonton, Melissa Gorman initially planned to spend between $20,000 to $25,000.

"Then, when I started talking to venues and started to talk to caterers, then the price of the dress, the invitations, favours, the cake, all of the components, I realized the my budget wasn't realistic -- so my budget did go up," recalled Gorman, editor of Wedding Obsession, a Canadian wedding blog dedicated to the modern bride.

In the end, the final tally was about $33,000 for approximately 150 guests.

"I planned far in advance so that I was able to make the money to pay for it, but essentially, yes, you could say I did dip into my savings -- but I didn't go into debt," said Gorman. "Basically, money I had allotted for other things I used to pay for my wedding."

Gorman said one reason her budget surged was underestimating the cost of feeding guests.

"You're looking at spending anywhere from $25 to $75 per person for food. And then not just that, there's also alcohol involved," she said. "Depending on whether you want an open bar, limited bar, drink tickets, all of that stuff adds up."

Barker-Merz suggested individuals start putting together a budget and setting aside money monthly for an affordable event. She recommends a tax-free savings account as a good investment vehicle.

To help scale back on costs, Gorman took on a lot of do-it-yourself projects such as packaging her own favours. But as she reflects on her day four years on, she admits she would approach the process differently today.

"I loved my wedding and I have no regrets. But if I could have gone back I would have scaled it down, I would have made it more intimate. And I think a lot of things I worried about and wanted to spend money on probably weren't really worth it."

The online survey of 500 adults who are not currently married but at least somewhat likely to get married in the future was conducted for BMO InvestorLine by Pollara between April 11-15. The margin of error is plus or minus 4.4 percentage points, 19 times out of 20.