Key takeaways
- Sink and tub stoppers are different fittings, not different sizes of the same thing.
- Tub drains are usually 1.5 inches, sometimes 2; sink drains are 1.25, sometimes 1.5.
- Identify the mechanism first: toe-touch, lift-and-turn, or a linkage from the overflow plate.
- Measure the inside of the drain opening, not the trim ring or the pipe below.
- A 1.5 inch tub drain and a 1.5 inch sink drain are still not interchangeable.
If you are standing in a bathroom holding a sink stopper and looking at a bathtub drain, the answer is no - it will not fit, and it is not a small difference you can work around with a bigger washer. Tub drains and sink drains are two different fittings with different sizes and different mechanisms, and buying the wrong one is the most common reason a stopper gets returned.
Why sink stoppers and tub stoppers are not interchangeable
A bathroom sink drain is a small opening, usually 1.25 inches and sometimes 1.5, with a seat that a stopper presses down onto. The stopper is a plunger moved by a rod behind the faucet. A bathtub drain is larger - commonly 1.5 inches, sometimes 2 - and most tub stoppers are not a plunger at all: they are a toe-touch fitting, a rotating lift-and-turn assembly, or a plug operated by a lever on the overflow plate at the end of the tub. Different diameter, different hardware, different way of sealing. A sink stopper in a tub drain sits in the hole and does nothing useful.
The three tub stopper types
The most common is the toe-touch or push-pull stopper: a plunger set into the drain that you press to close and press again to open. It seals with an O-ring around its base, and when it stops holding water the O-ring is the first thing to check. The second is lift-and-turn: a flat stopper you rotate a quarter turn to seal, with a cam underneath that raises and lowers it. The third is the linkage or trip-lever style, where the stopper is connected by a rod to a lever on the overflow plate - the same mechanism a bathroom sink uses, scaled up. If you cannot see how your stopper operates, look at the overflow plate: a lever there means a linkage, a plain plate means toe-touch or lift-and-turn.
Measuring a tub drain correctly
Measure the inside diameter of the drain opening, not the outside of the trim ring and not the pipe under the floor. A ruler across the opening is usually enough; if the drain is recessed, measure the widest point you can reach. Then check what you are replacing: if the old stopper was a plunger, the new one has to match the drain shoe it sits in, not just the diameter. And if the whole drain assembly is being replaced, note the thread and the depth of the shoe, because a stopper and a drain body are separate purchases.
Common tub drain sizes
Most tub drains are 1.5 inches, with 2 inch drains in some older and some larger tubs. Sink drains are 1.25 inches in most bathrooms and 1.5 in a minority - which is precisely where the confusion comes from: a 1.5 inch tub drain and a 1.5 inch sink drain are the same number and still not the same fitting.
| Sink drain | Bathtub drain | |
|---|---|---|
| Typical opening | 1.25 inch (some 1.5) | 1.5 inch (some 2) |
| Stopper mechanism | Pop-up plunger moved by a rod behind the faucet | Toe-touch, lift-and-turn, or a linkage from the overflow plate |
| Overflow | Overflow hole in the basin wall | Overflow plate on the tub wall, often linked to the stopper |
| What we sell | Yes - pop-up stopper with a hair catcher, 1.25 and 1.5 | No - match your drain shoe and buy a tub stopper |
If the stopper leaks or will not hold
Check the seal first. Scale from hard water, a flattened O-ring or a pitted seat will all let water past, and vinegar plus a soft brush often revives a scaled stopper. If the seal is cracked or the seat is corroded, replacement is the honest fix - sized to your drain. On a linkage-style stopper, a rod set too high stops the stopper seating fully, and that adjustment is under the tub, not in the drain.
If you actually need a sink stopper
Then the sink is the one to measure. Our own pop-up stopper with a hair catcher is built for bathroom and kitchen sink drains at 1.25 and 1.5 inches, and it ships with seals to suit both. We do not sell bathtub stoppers - tub drains are a different fitting with a different mechanism, and pretending otherwise would just create returns. If you are between the two, measure the opening first: that one number tells you which product you are actually shopping for.
Then measure the drain opening with our guide to sink drain stopper sizes - and if the sink is not sealing, start with five fixes for a leaking pop-up drain.
The bottom line
Sink and tub stoppers are different fittings: 1.25 versus 1.5 or 2 inches, a plunger versus a toe-touch, lift-and-turn or linkage assembly. Identify the mechanism, measure the inside of the opening, and buy for the fixture you have. If it is a sink, measure and we will fit it; if it is a tub, match the drain shoe and buy a tub stopper.
If that is the part you are stuck on, How a Pop-Up Sink Drain Stopper with a Hair Catcher Keeps Your Bathroom & Kitchen Sink Flowing has the step-by-step.
Related reading
- Sink drain stopper sizes: how to measure yours correctly
- Sink drain stopper vs bathtub drain stopper: what is the difference?
- Sink stopper won't hold water? 5 fixes for a leaking pop-up drain
If the parts above the drain are what you are replacing, the one we make is our pop-up sink drain stopper - the basket lifts out, so cleaning it is a ten-second job.