Some stories rely heavily on dialogue. Others have very little. Most strike a balance somewhere in between. To determine what's right for your own story, consider the effect so much dialogue has on the reader's experience. What atmosphere does it create? How does it impact the reader's understanding of the characters or the situation?
Ernest Hemingway's short story “The Killers" is predominately dialogue and that's part of what makes it effective. Two men walk into a diner for a meal. They try to order dinner, but are too early. Frustrated with their server, George, they settle on eggs instead:
“Got anything to drink?" Al asked.
“Silver beer, beyo, ginger-ale," George said.
“I mean you got anything to drink?"
“Just those I said."
“This is a hot town," said the other. “What do they call it?"
“Ever hear of it?" Al asked his friend.
“No," said the friend.
“What do you do here nights?" Al asked.
“They eat the dinner," his friend said. “They all come here and eat the big dinner."
“That's right," George said.
“So you think that's right?" Al asked George.
“You're a pretty bright boy, aren't you?"
The tension is palpable. The men aren't familiar with Summit and it's clear they have disdain for it. George's agreement to the sarcastic remark about Summit's nightlife seems to irk the men, and their antagonism toward George escalates. The story gets rather sticky—the men are in town to kill a local boxer—and the emphasis on dialogue adds to the mystery and increasing fear of these men who have such sinister intensions.
Keep in mind the role of dialogue and its limitations. Some dialogue-heavy fictions fail because the dialogue is used carelessly. Make sure you're not cramming information into dialogue when it might be more appropriate in narrative, as in this line where Tom talks to his wife:
“Renee, there's no way I'm driving that way to my mother's. We both know it shaves twenty minutes off the trip, but my sister died on that very same route at the sharp curve just months ago. I can't bear to go by it."
Renee already knows it's a short cut and that his sister died there. Would he really say this? When we speak we take into consideration what the listener already knows—without even thinking about it—and that's not happening here, so it sounds forced.
Also, be thoughtful when considering what to include in an exchange. Crafting a scene is all about selectivity and you should include only what's important. Here, I've added much more than necessary to a scene featuring this same couple on the evening they're to go to Tom's mother's house:
“I'm glad you're home," Renee said from the kitchen. “I told your mom we'd be there by five."
“It was a rough day at work." Tom took a tumbler from the cabinet. “ I never thought I'd get out of there."
“The Schneider case again?"
“Yeah," Tom said, pouring the gin. “And reviews are coming up next week, too."
“You work so hard," Renee said.
“What can I do?" Tom said.
This kind of post-work chitchat might be commonplace in real life, but it's not terribly exciting in fiction. If the heart of the scene is to reveal Tom's insecurities about the drive, we don't need all this fluff taking up space.
Since there's no set formula for how much dialogue you can use, keep an eye out for these common pitfalls and consider the effect of a dialogue-heavy read in the context of your work. This should help you figure out if you've used too much or just the right amount.