The fact sheet for the Isobel Cup says it stands 25 ½ inches tall and weighs 15 pounds. Under certain circumstances, though, the dimensions of the trophy that goes to the National Women’s Hockey League champion can vary.

“That’s until you win it,’’ NWHL Commissioner Dani Rylan said. “Then, they say it’s weightless.’’

The Whitecaps hope to test that theory for themselves Sunday, when they play Buffalo in the Isobel Cup final at Tria Rink. It’s already been a memorable season for the league’s first expansion franchise. On the ice, the Whitecaps went 12-4 in the regular season, earned the top seed for the playoffs and beat the Metropolitan Riveters 5-1 in Friday’s semifinals. They’ve been a smashing success on the business side, too, giving a big boost to the young league in their initial season as a member.

All 1,200 tickets have been sold for Sunday’s championship game, making the Whitecaps the first team in league history to sell out all its home games. They lead the NWHL in merchandise sales and have a robust social-media presence, contributing to growing awareness of the four-year-old league.

“We had high expectations [for the Whitecaps], and all of them were definitely surpassed,’’ Rylan said. “We couldn’t have asked for anything better.’’

The overwhelming reception for the Whitecaps could lead to further expansion, Rylan said. And with tickets in such high demand that they were being resold through ticket brokers and scalpers — another league first — she is exploring adding more home games next season, or moving some to a larger venue.

While Rylan is looking toward the future, the Whitecaps are rooted in the present. Amanda Boulier, a finalist for NWHL defender of the year, said the players have “a ton’’ of pride in what they have achieved so far, a feeling she expects to fuel them as they play for the title.

“It’s going to be a grind from start to finish,’’ she said. “Being able to win the league [regular-season] title, then put ourselves into position to win a championship, is certainly a great feat. But we won’t be satisfied until we get that cup on Sunday.’’

Right from the start, the Whitecaps seemed destined to avoid the growing pains of a typical expansion franchise. Established 15 years ago by general manager and co-head coach Jack Brodt, they entered the league last spring with a solid foundation, local name recognition, and a reputation and location that attracted high-end players.

The team had been playing an independent schedule since the 2011-12 season, when its former league folded. Brodt said the first season in the NWHL has “gone very well’’ from his perspective. Having a permanent home at the brand-new Tria Rink has helped boost the Whitecaps’ fan base, as has marketing and promotional support from the Wild.

“The league has done well by us,’’ Brodt said. “We love the facility, which I think is the nicest one in the league, and it’s been really good to work with the Wild. And the fans have been amazing.’’

That’s a description repeated by many players, and by Rylan. Given Minnesota’s love for hockey, she expected the market to be receptive, but she has been astonished by the enthusiasm.

Rylan said the plan is for the Whitecaps to play at Tria again next season, and she hopes to expand the team’s relationship with the Wild. Though there is no timetable for a second expansion, she said the NWHL is “pursuing conversations’’ with other markets and would like to add another Midwest team.

The Whitecaps’ grand debut has contributed to what Rylan called an outstanding overall year for the NWHL. The only thing that could make it better, Boulier said, would be to raise the Isobel Cup in a grand finale.

“This has been so incredible, for the league and for women’s hockey,’’ she said. “I just had someone come up to me and say they weren’t a hockey fan before, but they heard about the NWHL, and they’re now a diehard fan.

“That was such a good feeling. That’s what it’s all about, growing the sport for the next generation.’’