Kerry McAuliffe weighs that question every time she looks up the cost of summer camp for one of her three children or opens a stuffed closet in her Morningside Heights apartment, close to Columbia University in Manhattan, and has a basketball fall on her head.

“We’re in a place where it’s very tight,” Ms. McAuliffe said. Her family of five lives on $140,000 a year.

Their housing solution: become the super

The family’s monthly rent — $2,700 for their three-bedroom apartment — is their biggest expense, as it is for most New Yorkers. But they have a hack to make their housing more affordable: Ms. McAuliffe’s husband, Jake Kassman, is the superintendent for their building and the one next door.

He took on the super job a few years ago, after the couple’s first child was born and the family realized they wouldn’t be able to live only on Mr. Kassman’s roughly $110,000 salary as an M.R.I. technician at Columbia University’s medical center. Ms. McAuliffe had left her job in education around the same time, because the cost of child care would have canceled out her paycheck.

There are perks: The family now takes in an extra $30,000 or so a year, including a few months of free rent, and their landlord recently let them knock down a wall to take over an extra bedroom in a vacant unit next door.

‘Someone gets financial aid. Why not you?’

Ms. McAuliffe and Mr. Kassman spend much of their free time plotting how to provide their children with as many opportunities as they can, while weighing the cost of school and activities.

The family had never seriously considered private school until a chance meeting on a playground a few years ago. Ms. McAuliffe was speaking with a neighbor who encouraged her to apply for financial aid, asking: “Someone gets financial aid. Why not you?”

The family applied to the nearby Cathedral School, which costs about $65,000 a year, and received a package that would cover more than half the cost for their daughter.

The couple’s eldest has started to ask about the after-school activities and camps that many of her friends go to. The couple splurged on a week of theater camp, which cost $1,000, and a season of swim team at the local pool, which runs $800, for her.

But Ms. McAuliffe feels a pang of guilt whenever she signs her daughter up for an activity, because she can’t afford classes for the younger children, both boys.

“One day we’ll have to do a reckoning of where the funds go,” she said. “My son is like, ‘Can I do swim team?’ And I’m like, ‘We’ll see.’”

They cut back on babysitting but splurge for pizza night

Since nearly all of the family’s budget goes to rent and education, Ms. McAuliffe and Mr. Kassman have made peace with the fact that the frequent nights out and elaborate birthday parties that other families can afford are not part of their lives.

The couple gets a babysitter only about three times a year, so they can go out to dinner for each of their birthdays and their anniversary. They know it would be good for them to go out on their own more. But, Ms. McAuliffe said, “I’m trying to come to terms with the idea that this is a chapter in life, and hopefully we’ll be able to grow old together and talk about those things later.”

The family’s weekly treat is Friday night pizza delivery, which usually costs $25.

For the rest of the week, Ms. McAuliffe tries to keep the weekly grocery bill to about $300. She relies on quesadillas and pasta to feed the whole family, and is relieved that all three kids happily eat broccoli. But she worries about how much she’ll have to stock her fridge once she has two preteen boys in the house.

On weekends, the family mostly sticks to the city’s bounty of free parks and playgrounds.

The couple has a car, which they use to go visit family on Long Island. They sometimes take day trips upstate, to a farm or a hike, but usually drive home at night to avoid paying for an Airbnb. Just the cost of gas, an activity and a meal for the day usually runs them about $300.

Their Christmas strategy: Old toys are new

For Christmas, Ms. McAuliffe wrapped the open puzzles and toys that her oldest child had grown out of to make them look like new gifts for her younger children.

Instead of birthday parties where the whole class is invited, Ms. McAuliffe has each of her children pick a special activity, like a trip to the Statue of Liberty, that they can attend with a friend.

The family’s sacrosanct splurge is a short summer vacation, usually four nights, somewhere within driving distance of the city, which typically costs about $3,000.

That tradition helps the couple feel better about skipping so much of what their peers can afford. None of her children has ever been on an airplane, and she doesn’t expect that to change soon.

Ms. McAuliffe recently spoke with a friend who grew up in New York but left the city because of the cost of living. He asked her why she was staying, when life could be so much easier somewhere else.

“I just like being in New York,” Ms. McAuliffe said. “There’s so much to do the second you step outside your door.”