The tub fills one end of the room, nobody has taken a bath in it for ages, and stepping over its wall to shower is getting harder. Converting tubs to walk-in showers is regular work for us, and the cost comes down to a few things you can understand before anyone visits: the drain, the valve, the walls, the shower floor, and the glass.

What a conversion usually includes

A full conversion is more than pulling out a tub and setting a base in its place. A complete job usually covers:

• Removing the tub and its wall surround, down to the studs where needed

• Checking the subfloor and the bottom of the walls once the tub is out

• Drain and valve work for a shower instead of a tub

• A shower floor that slopes to the drain, either a preformed base or a tiled floor

• Backer board, a waterproofing system, and new wall surfaces

• A curb or low threshold, glass or a curtain, and new trim

• Drywall patching and paint where the old surround met the walls

How each of those is handled is where conversions differ, and where the cost moves.

The decisions that move the number

Staying in the tub’s footprint or going bigger

Most conversions fit inside the old tub alcove, which keeps the walls, toilet, and vanity where they are. Current California plumbing code generally calls for a larger drain on a shower than on a tub, but it allows a tub-size drain for a tub-to-shower retrofit when the new shower is no more than 36 inches wide and 60 inches long. Go past that, or widen the shower into a closet or vanity area, and you’re adding drain and wall work that is evaluated during the in-home consultation.

Drain location and the floor under it

A tub drain sits at one end, while a shower drain is usually in the center or along one wall as a linear drain. Moving it on a concrete slab means opening the concrete to reach the line, and on a raised floor the work happens from the crawl space. How much floor has to be opened is one of the biggest swings in a conversion.

The valve and controls

The old tub and shower valve is often replaced rather than reused, since the wall is open anyway. Any new shower valve must protect against scalding, which means a pressure-balancing or thermostatic design. Adding a handheld on a slide bar or a second showerhead means more valve and piping work.

Shower floor and waterproofing

A preformed shower base installs faster and usually costs less than a tiled floor. A tiled floor is built to slope toward the drain over a waterproofing layer, either a traditional mortar bed with a liner or a bonded membrane, and it takes more labor and curing time. The method matters more than the brand, as long as it’s a complete system installed to the manufacturer’s instructions; read more about shower tile and waterproofing.

Wall surface

Solid-surface or acrylic panels go up quickly with few joints. Tile offers more choice and more labor: large-format tile needs flatter walls, small tile means more grout lines, and patterns like herringbone add cuts. A recessed niche adds waterproofing detail. The trade-offs are laid out in tile vs acrylic showers.

Entry and glass

A standard curb is the simplest entry. A low threshold or curbless entry needs the floor recessed so water stays in, which depends on how your floor is built; compare the options in curbless vs standard showers. For glass, a curtain costs least and a framed door sits in the middle, while frameless glass usually costs the most, since the panels are thicker, the hardware is heavier, and everything is made to measure after the tile is done.

What the old tub might be hiding

Tubs tend to fail at the edges. Caulk lines crack, water gets behind the surround, and over time the subfloor and the bottom of the wall can soften without showing much from the outside. How far it goes isn’t clear until the tub is out.

Older houses add their own surprises. Cast-iron tubs are heavy enough that they’re often broken up to get them out, older valves may not meet today’s anti-scald requirements, and galvanized supply lines may be in poor shape. Replacing supply lines beyond the shower involves licensed plumbing trades and is evaluated during the in-home consultation. Plan for a decision point after demolition, and keep part of the budget free for it.

Is a conversion right for your bathroom?

A conversion makes the most sense when the tub isn’t used for bathing and a shower is what everyone needs every day. A low entry also makes the room easier to use as you get older, or for anyone in the house who has trouble stepping over a tub wall.

It deserves a second thought if this is the only tub in the house and you have young children or pets to bathe. If you’re still deciding how far to go, compare a tub-to-shower conversion with a full bathroom remodel.

Comparing conversion quotes

Conversion quotes vary widely because they often describe different jobs. A fair comparison checks that each quote names:

• How far demolition goes, and whether the walls come down to the studs

• The waterproofing method and the shower floor type

• Drain and valve work, including the valve type

• Wall material, tile height, and any niche or bench

• The glass type, or whether glass is excluded

• Drywall repair, paint, and disposal

• How damage found after demolition will be handled and priced

An acrylic surround fastened over the old walls is a different product from a tiled shower on a new waterproofing system. Both have their place, but they shouldn’t be compared as if they were the same job.

Getting a number for your bathroom

Choosing Tub to Walk-In Shower in the bathroom estimator brings up a follow-up question about glass. Your answers on size, tile, vanity, layout, plumbing, and finish level shape a planning range for the whole bathroom project, not the conversion alone, because the rest of the room changes the total.

After that, a free in-home consultation confirms the drain location, the valve, visible signs of water damage, and whether permits are needed. Read more about tub-to-shower conversions while you plan.