If you are planning to attend a wedding this spring or summer, how much should you spend on the gift? 

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Couples are spending an average of $30,000 on the big day and guests will spend an average $673 to attend, up 13 percent from last year and 21 percent from 2013, according to research from American Express Spending and Saving Tracker.

Despite the increased costs, attendees are actually spending a little less on the gift, about $106, compared to the average of $109 in 2014. If the recipient is a family member, guests indicated they would spend $142, down from $150 last year.

What will consumers who attend a wedding spend their money on?:

  • Airfare - $225, up 125 percent from 2014
  • Hotel - $170, up 86 percent from 2014
  • Dining out - $116, up 90 percent from 2014
  • Dressing up - $95, up 53 percent from 2014

"Guests can spend anywhere from $500 to $1,000 to attend a wedding. If it's a destination wedding, it can cost even more," said Jamie Miles, managing editor of The Knot.com. "But, when it comes to a gift, we generally estimate what you should spend based on your relationship with the couple."

The Knot.com recommends the following guidelines for gift-givers:

  • For a co-worker - spend $75 to $100
  • For a relative or friend - spend $100 to $125
  • For a close relative or close friend - spend $100 to more than $150

Gone are the days when wedding guests purchased a gift based on the cost the couple spends on the plate.

"It really should be based on your relationship and your budget. You may be served a $300 dinner and you may not be able to afford that," Miles said. "Plus, there may be several activities and events leading up to the wedding, like an engagement party, bridal shower and bachelor and bachelorette parties, which will cost you money."

Gifts for pre-wedding celebrations include:

  • Bridal shower gift - $77
  • Bachelor/bachelorette party gift - $86
  • Engagement party gift - $89

"The couple should know and respect that you're spending your money on other things leading up to the big day. It's not about what you should be spending, but what you can afford to spend and how that reflects upon your relationship," Miles said.

If you are looking to save money, Miles suggests going in on a group gift.

"If you have several people splurging on a big ticket item, it can be a very nice gesture," Miles said. "You can also buy early. Often times, the earlier items on the registry are snatched up. Typically, 46 percent of a couple's registry will be items under $50 and if you shop earlier, you have more items you can buy at a lower price."

When it comes to the actual present, 33 percent of guests give cash and 32 percent give items from the couple's registry. When asked what they'd want to receive if they were getting hitched, 49 percent of Americans said cash and 19 percent said gifts from the registry.