Rotten Tomatoes has built an express lane for finding out whether a movie sucks or will change your life. The service has become the standard for critical opinion now that there are thousands of movie reviews published every week — and without celebrity voices like Roger Ebert around anymore — because of how easy it is to use. You don't have to go further than the site's front page to get an instant snapshot of a given week's releases.

But those percentages and tomato icons may not mean what you think.

Understanding the Meter

To calculate a Tomatometer percentage, the site rounds up reviews by critics who have been approved based on set criteria. According to a rep for the site, critics designate whether their reviews are considered positive (fresh) or negative (rotten), and in cases where it's more difficult to tell, the Rotten Tomatoes editorial staff reaches out to critics for clarification.

The number of positive reviews is then divided by the total number of write-ups considered, and then you get the movie's Tomatometer rating.

People love Rotten Tomatoes because it's easy to use. The Tomatometer gives the false sense of understanding many knowledgeable opinions by looking at a single number. That percentage and the Fresh status that can come with it (anything over 60 percent) have become highly regarded measures of film quality to the point where DVD covers boast of the certification and it's a fanboy rage-inducing act to ruin a movie's perfect score.

The problem is that the Tomatometer doesn't measure film's quality in the eyes of critics. What it is is a record of critical agreement.

Where It Falls Short

It starts with the Fresh versus Rotten distinction, which only allows for two options. Everyone has seen a movie they kind of liked, and so have critics, but to fit into the Rotten Tomatoes formula, a writer has to put that okay movie on equal footing with one he or she loved. It's possible by that logic that a movie could receive nothing but lukewarm reviews and walk away with a 100 percent Fresh rating.

Likewise, divisive movies don't fare well by the standards of the site. Controversial films can have half of the critical mass (which you may agree with) swept off their feet by it, while leaving the other half cold. That movie gets a 50 percent, which can only be seen as a failing grade by the Rotten Tomatoes framing.

These blind spots are not problems within Rotten Tomatoes' formula. It's how readers use their data that creates the misunderstanding. Though the Tomatometer very often lines up with popular opinion, more is lost when the site converts an 800-word review to a plus or a minus than it might admit.

How To Use It

What Rotten Tomatoes lacks in nuance, it makes up for in thoroughness. It's beneficial for a publication to be included in the rating because it can drive traffic to individual reviews, so there's never a shortage of write-ups to choose from. You can find a link to almost any review of a movie on one page, complete with a blurb.

The obvious next place to look after the Tomatometer is the average rating, which is located directly beneath the percentage on a movie's main page. This figure is the average critical rating on a ten-point scale, closer to what Metacritic calculates. Here, you can get a better idea of the average review and even see through any anomalies in the Tomatometer.

Then, read more reviews. Take the time. It can enrich your appreciation for a movie you already like, convince you to take another look at one you didn't, or give you a better understanding of why a film failed. A deeper understanding of a movie is the only way to squeeze the real meaning out of the Tomatometer.

By not factoring in the gray areas between "good" and "bad" we sacrifice nuance for digestibility. When it comes to something as subjective as taste in movies, it takes more than an understanding of how many critics liked a film to decide whether we should see it. Finding a great film often means taking a risk and seeing something unknown, and not just what's popular.