Giving tired cabinets an upgrade with new hardware is one of the oldest tricks known to decorators — and for good reason. It’s a surprisingly easy way to transform a kitchen or bathroom.

The same strategy works just as well on a larger scale, with doors. New hardware can go a long way toward making even the most ordinary doors look special.

“It’s very, very important, because it’s the touchpoint when you enter a home or enter another room,” said Piet Boon, a Dutch designer who is a stickler when it comes to hardware, and who has designed collections of his own for Formani. “Sometimes we use very flat doors, and then the door handle becomes this sort of beautiful object, like a piece of functional art.”

Magdalena Keck, an interior designer in New York, likened door hardware to fashion accessories. “Let’s say you’re dressed all in black, with a really simple outfit, but have a beautiful watch or great shoes,” she said. In the same way, “you can totally elevate a space just with hardware.”

But replacing the hardware on doors isn’t nearly as simple as changing cabinet hardware. There are more measurements to consider and various components that need to work together. And because door hardware tends to be more expensive, it’s generally a long-term commitment, so understanding how the parts and finishes will perform over time is crucial.

To help think through all the decisions that need to be made when you’re selecting new hardware, we asked designers and suppliers for advice.

Know Your Measurements

Before buying anything, take a few key measurements, lest you find yourself flummoxed by your new door hardware when you try to install it.

If the hardware will be installed on an existing door, the existing holes will dictate many of the specifications. (If it will be installed on a new door that hasn’t been drilled or is being custom made, you can skip this step.)

One key measurement is the backset: the distance from the edge of the door to the center of the handle. “We go from an inch and a half to two and three-quarters,” said Kevin Bean, the director of product marketing at Baldwin Hardware, a range that accommodates various types of doors, from flat slabs to those with panels or glass.

The thickness of the door is also important. “Typically speaking, most hardware you buy is going to work just fine on an-inch-and-three-eighths to an-inch-and-three-quarters door,” which are standard thicknesses, Mr. Bean said. But many people have thinner or thicker doors — in which case an additional kit may be required to install the handles.

Finally, make a note of the size of the hole behind the existing escutcheon (sometimes called a rosette or backplate), as the replacement hardware will need to completely cover it.

Latch It

There are two basic types of latches: tubular and mortise.

Tubular latches are more common and have a slender mechanism that is easy to install in a drilled hole in the edge of the door. A locking function can be added with a button or thumb turn on the door handle itself, or with a separate deadbolt.

The downside of tubular latches is that they can be flimsy.

Mortise latches and locks tend to be stronger — and more expensive — with a large metal box that fits into a pocket in the side of the door. If there is an integrated lock, it is usually controlled by a separate thumb turn on the door. These latches are typically found on older doors and new, high-end doors.

So which should you choose? If you’re replacing hardware on an existing door, you haven’t got a choice, because the two kinds of latches are not interchangeable. So you’re stuck with whatever kind of latch you already have.

To figure out what you’ve got, look at the edge of the door. A tubular latch will have only a small metal plate around it, while a mortise latch “is going to look like one big hunk of metal in your door,” and it will be at least a few inches high, Mr. Bean said.

If you’re choosing a latch for a new door, you can go with either mechanism. But Andrew Beren, the president of Katonah Architectural Hardware, recommended using a mortise latch, which is not only more resilient, but can be made with stronger springs to support heavier door levers.

Tubular latches are weaker, he noted, and sometimes allow levers to sink under their own weight over time: “Instead of being horizontal, it drops two, three, four degrees — that would make me crazy.”

Choose Knobs or Levers

There are countless door-handle designs on the market, and choosing one largely comes down to personal style. But one of the biggest decisions is between knobs and levers.

From a functional standpoint, Mr. Beren said, there are advantages to levers, which are popular with his customers. “The trend is more toward levers,” he said, noting that they are easier to use if you have compromised hand strength or if you’re carrying things.

Few people, of course, choose door handles solely based on functionality. For most, it’s about finding a model that reflects the design of the room, or “emphasizes the concept of the home,” said Jonathan Savage, an interior designer in Nashville. “If you have an Art Deco interior, it’s really nice to complement that interior with Art Deco hardware, for instance.”

For a home he designed in Memphis with traditional flourishes, Mr. Savage chose Acanthus oval-shaped knobs with a leafy pattern from Rocky Mountain Hardware. “That hardware was a classic choice to complement the classic Southern architecture,” he said.

For a modern apartment in a Nashville high-rise, however, he chose a streamlined lever with a flat profile and square escutcheon from Nanz: “It’s a modern lever, done in a clean and simple way.”

Or Mix It Up

If you want something truly distinctive, there are other options. One of Mr. Boon’s favorites is a T-shaped handle that resembles a centered vertical bar when at rest. “It’s so beautiful,” he said.

And he doesn’t necessarily use the same handle on both sides of the door. Instead, he often uses a T-shaped handle on the pull side of a door and a standard horizontal lever on the push side — for variety and to indicate which way the door swings.

Select the Hinges

Most doors attach to frames with butt hinges, which have visible knuckles whether the door is open or closed. If you’re replacing hinges on an existing door, it’s usually easiest to match the style and size of what is already there.

If you’re installing new doors, there’s more freedom to choose. Many designers prefer hinges that are concealed from view. “I like hinges that disappear, because there are not so many beautiful hinges,” said Mr. Boon, who favors pivot hinges that attach at the top and bottom of a door, rather than at the side.

Ms. Keck is a fan of pivot hinges, but she also likes Soss hinges, which are installed on the side of a door and are completely concealed when the door is closed. (Tectus is another brand that makes similar hinges.)

The look it creates is streamlined and clean, she said: “You just see the door and doorknob or lever.”

Find Your Finish

Some specialty door handles are made of crystal, porcelain or wood, but the majority are metal. And within the world of metal door handles, there is an almost bewildering array of finish options, from mirror-like polished chrome to heavily distressed antique brass.

To choose the ideal finish, consider the other metal fixtures in your home, as well as the home’s age and style. If the plumbing fixtures in your bathrooms and kitchen are satin nickel, you may want the same finish for your door hardware. For a Craftsman-style house with dark wood paneling, on the other hand, a deep oil-rubbed bronze may be the better choice.

Just as important as the initial appearance of the finish is understanding how it will (or won’t) evolve. Some finishes, like unlacquered brass and oil-rubbed bronze, are intended to develop a timeworn patina as the hardware is used.

“We like a living finish that develops a patina with exposure to air and hand oils,” said Heather Hilliard, an interior designer in San Francisco. “It just looks more soulful.”

But despite her best efforts to convince her clients to choose living finishes, Ms. Hilliard said, some equate patina with undesirable wear.

If you’re worried about your door handles changing with use, options include lacquered brass, polished chrome, satin nickel and solid black. And for bombproof durability, there are stainless-steel handles and PVD (or physical vapor deposition) finishes, often recommended for homes in coastal areas.

Whatever you end up with, it’s worth taking the time to choose carefully.

“Hardware is super important,” Ms. Keck said. “You can have a very simple space, but then beautiful, well-designed, well-detailed hardware changes everything.”

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