‘Helsing’ B.O. comes in a little lighter

U blames miscalculation on Mother's Day

Universal took a bite out of “Van Helsing’s” opening on Monday.

According to the actual weekend box office figures, monster pic opened with $51.7 million — $2.5 million less than the studio’s Sunday estimate of $54.2 million.

U blames the difference on Mother’s Day: The studio miscalculated the effect of the holiday on its Sunday grosses, expecting a boost for the day.

“We always make our best efforts to give accurate estimates, but in this case the Sunday numbers did not live up to what we predicted,” studio rep Paul Pflug said.

Historically, Mother’s Day has helped pics with adult female and family appeal. This year, for instance, Revolution and Sony’s “13 Going on 30” performed better on Sunday than in previous weeks, declining just 19% from Saturday. As a result, its actual weekend take of $6.0 million was quite a bit higher than the Sunday estimate of $5.5 million.

“Van Helsing” didn’t get the same boost, falling 36% from Saturday to Sunday, $19.6 million to $12.6 million. The decline was in line with helmer Stephen Sommers’ other pics, including “The Mummy,” which also opened on Mother’s Day weekend.

Even in weeks without holidays, actual box office figures are usually lower than the studio estimates because distrib execs are guessing on Sunday mornings how their pics will play that day.

Given the uncertainty, the studios are remarkably accurate, pegging numbers within hundreds of thousands of dollars — not millions.

For example, last summer, U estimated “The Hulk” would open with $62.6 million and the actual figure was $62.1 million. Similarly, the U estimate on “Bruce Almighty” was $86.4 million, while the actual was $85.7 million. In both cases, the margin of error was less than 1%. On “Van Helsing,” the difference was nearly 5%.

Studios have been more widely off the mark before. Fox called the opening of “X-Men” in 2000 at $57.5 million on Sunday morning, but corrected it to $54.5 million the next day.