What Bath Faucet Hole Size Do I Actually Need for My Sink or Tub?

If you’re staring at your sink wondering about the right bath faucet hole size before you buy or drill anything, here’s the short version: the hole diameter itself is almost always the same — 1-3/8 inches (1.375″, or roughly 35 mm) — because faucet shanks are standardized. The part that trips people up isn’t the size of each hole, it’s how many holes you have and how far apart they sit. Get those two things right and your new faucet drops in without a fight. Get them wrong and you’re either buying a deck plate to hide extra holes or drilling into a brand-new sink.

Below, we’ll walk through exact measurements, how to figure out what your existing sink or tub deck was drilled for, what to do when the numbers don’t match, and how thick your countertop can be before the faucet won’t reach. This is the same information our product team at vevetta references when customers ask “will this faucet fit my sink?” — practical, spec-first, no guesswork.

What is the standard bath faucet hole size?

The standard bath faucet hole size is 1-3/8 inches (1.375″, or about 35 mm) in diameter. This is the size cut into virtually every drop-in and undermount bathroom sink sold in North America, and it’s the size deck-mount tub fillers expect too. Faucet manufacturers build the threaded shank (the part that pokes down through the counter) to slide through a 1-3/8″ opening, then secure it from below with a mounting nut.

A few things worth knowing so you’re not caught out:

• 1-3/8″ fits most single-hole and widespread faucets. The shank on a single-handle faucet is usually the widest part, and it’s designed for this opening.
• Some faucets tolerate up to 1-1/2″. If a previous faucet left a slightly larger hole, many faucets ship with a base or escutcheon wide enough to cover it. Check the spec sheet’s “minimum/maximum deck hole” line.
• Vessel and freestanding faucets are different. Wall-mounted and floor-mounted tub fillers don’t use a deck hole at all — they connect to rough-in plumbing behind the wall or in the floor, so the “hole size” question doesn’t apply the same way.

Because the diameter is so consistent, most fitment problems have nothing to do with whether a faucet is “1-3/8 inch.” They come down to hole count and spacing, which we’ll cover next.

How many holes does my bathroom sink have — and why does it matter?

Count the holes in your sink deck before anything else, because that single number decides which faucet configurations you can install without modification. Bathroom sinks come pre-drilled in three common patterns: 1 hole, 3 holes, or 0 holes (undrilled). A faucet built for one pattern won’t cleanly fit another unless you adapt it.

Here’s how the counts break down and what each accepts:

The key insight: a 3-hole sink can usually accept a single-hole faucet if the faucet comes with (or you buy) a deck plate — also called an escutcheon — to cover the two outer holes. But a single-hole sink generally cannot accept a widespread faucet without drilling two more holes, which is a real job on porcelain, glass, or stone. When in doubt, match the faucet to the sink, not the other way around.

If your sink came with the faucet, the drilling already matches. It’s when you’re swapping to a new style — say, going from a builder-grade centerset to a sleek single-handle unit — that the counting matters most.

What’s the difference between 4-inch centerset and 8-inch widespread spacing?

The difference is the distance between the outer holes, measured center-to-center: 4 inches for centerset, 8 inches for widespread. That spacing determines which faucet you can bolt down, and it’s the single most common reason a faucet “won’t fit.”

Let’s define each clearly:

• Centerset (4″): The two handles and the spout sit close together, often on a single base plate that spans all three holes. The outer holes are 4 inches apart center-to-center. This is the most common builder-grade layout in the U.S.
• Mini-widespread (4″): Looks like a widespread — three separate pieces — but the outer holes are still 4″ apart, so it fits a standard centerset sink. A nice upgrade look on existing drilling.
• Widespread (8″): The hot handle, cold handle, and spout are three fully separate pieces connected underneath by flexible tubing. Outer holes are typically 8 inches apart, though “widespread” can range roughly 6″ to 16″ on some models.

Measure yours with a tape measure from the center of the left hole to the center of the right hole. If it’s 4″, buy centerset or mini-widespread. If it’s 8″ (or anywhere in the 6″–16″ widespread band that your faucet lists), buy widespread. Getting this backward is the classic return-to-the-store mistake — the individual hole size may be fine, but the handles won’t reach their holes.

One more note for tub decks: deck-mount tub fillers and roman tub faucets follow the same logic but with wider spreads, often 8″ to 16″ across three or four holes, plus a separate hole for a handheld sprayer or diverter. Always drill from the manufacturer’s template, never from a generic number.

How do I measure my existing faucet holes before buying a new faucet?

Measure two things and you’re done: the diameter of one hole and the center-to-center distance between the outer holes. Do it before you order and you’ll skip nearly every fitment headache.

Here’s the reliable way to do it:

1. Clear the deck. If a faucet is already installed, you can measure spacing from the top without removing it — measure from the center of one handle to the center of the other.
2. Measure hole diameter. With the faucet off, put a tape or caliper across a single hole. Expect 1-3/8″. If it reads closer to 1-1/2″, note that — you’ll want a faucet base that covers it.
3. Measure center-to-center spacing. From the middle of the leftmost hole to the middle of the rightmost hole. 4″ or 8″ are the answers you’re hoping for.
4. Measure countertop/deck thickness. This is the step people forget. Total thickness of the sink deck plus any mounting surface tells you whether the faucet’s shank and supply connections will reach through and still leave room for the mounting nut.
5. Note the faucet-to-wall clearance. Make sure the spout height and reach clear your backsplash and land water in the bowl, not on the rim.

Countertop thickness deserves a closer look, so we’ll give it its own section. But first, know that these measurements are also exactly what you’ll need if you’re upgrading supply lines or a deck plate at the same time — related jobs that often ride along with a faucet swap. If you’re also sorting out the water connections, our guide on what size a faucet supply line is pairs perfectly with this one, and if you’re covering extra holes on a kitchen-style deck, the replacement deck plate guide explains how escutcheons work.

Does countertop thickness affect whether the faucet fits the hole?

Yes — hole diameter is only half the story. Most bath faucets are engineered for a deck up to about 1-1/4″ to 1-1/2″ thick, and a thick stone counter or a counter plus a thick sink deck can exceed the shank length, leaving the mounting nut nothing to grab.

Why it matters: the faucet shank has to pass fully through the deck, then leave enough threaded length below for the washer and mounting nut to tighten against the underside. On a thin drop-in sink, there’s plenty of thread. On a 2″ honed granite slab with an undermount sink, the shank can come up short, or the supply connections can bottom out against the cabinet.

What to do about it:

• Check the spec sheet’s “maximum deck thickness.” Reputable manufacturers publish it. If yours doesn’t, that’s a red flag.
• Add up total thickness — counter + sink deck lip if the faucet mounts through both.
• Look for extended shanks or extension kits. Vessel faucets meant for thick vanity tops often ship with longer shanks precisely for this reason.
• Mind the supply lines. A thicker deck eats into the space below; make sure your supply lines are long enough and flexible enough to connect without kinking.

This is also why measuring beats assuming. A 1-3/8″ hole is meaningless if the faucet physically can’t reach the underside of a thick counter. If you run into leaks after install — sometimes a sign the mounting nut never seated properly on a too-thick deck — our walkthrough on how to fix a leaky faucet from underneath covers the exact connections involved.

Can I install a single-hole faucet on a 3-hole sink (or vice versa)?

Yes to the first, usually no to the second. You can mount a single-hole faucet on a 3-hole sink by adding a deck plate (escutcheon) that covers the two unused outer holes — most single-hole bath faucets include one or offer it as an accessory. Going the other way — putting a widespread faucet on a single-hole sink — requires drilling two additional 1-3/8″ holes at the correct spacing, which is difficult and risky on porcelain, tempered glass, or stone.

The practical playbook:

• Single-hole faucet → 3-hole sink: Easy. Use the included deck plate. The center hole handles the faucet; the plate hides the rest. This is the most flexible faucet choice if you’re not sure what your next sink will be.
• Centerset faucet → 3-hole sink (4″): Direct fit, no adapter needed.
• Widespread faucet → 1-hole sink: Not recommended. Drilling glass or fireclay often cracks it. If you love a widespread look on a single-hole sink, replace the sink instead — it’s cheaper than a shattered basin.
• Vessel faucet → 1-hole sink: Works well; vessel faucets are tall single-hole units made for above-counter bowls.

If you do need to drill, use a diamond hole saw rated for your material, go slow with water cooling, and use the manufacturer’s template so spacing and diameter come out exact. When the material is anything but a standard drop-in sink, hiring a fabricator is money well spent. And if your project is on the tub side rather than the sink, the height and clearance rules shift — our piece on vessel and wall-mount faucet height is a useful companion when you’re deciding between deck-mount and wall-mount.

Quick reference: bath faucet hole size and spacing at a glance

Here’s everything condensed so you can screenshot it before your hardware-store run. The single-hole diameter rarely changes; spacing and count are what you verify.

FAQ

Is a bath faucet hole size the same as a kitchen faucet hole size?

Yes — both use the same standard 1-3/8″ (35 mm) mounting hole diameter. The difference is in spacing and spout size, not the hole itself. Kitchen sinks are more often single-hole or have extra holes for sprayers and soap dispensers, but the individual hole cut is identical to a bathroom deck.

What if my hole is slightly bigger than 1-3/8 inches?

Many faucets tolerate a hole up to 1-1/2″ because their mounting base or gasket is wider than the shank. Check the faucet’s spec sheet for its listed maximum deck hole. If your hole is larger than the faucet allows, a mounting ring or deck plate can bridge the gap. A hole that’s too small, on the other hand, must be enlarged with a diamond bit — never force a shank through.

Can I drill new faucet holes in a porcelain or glass sink myself?

You can, but it’s risky. Porcelain, fireclay, and tempered glass crack easily. Use a diamond-grit hole saw sized to 1-3/8″, keep the bit wet to prevent heat cracks, run at low speed, and always work from the manufacturer’s template. Tempered glass especially can shatter — for stone and glass, a professional fabricator is the safer call.

How far apart should the holes be for a widespread bath faucet?

Standard widespread bath faucets are drilled 8 inches center-to-center between the outer holes. That said, “widespread” is a range; some models list anywhere from 6″ to 16″. Always confirm the exact spread on the faucet you’re buying and drill from its template rather than assuming 8″.

Do vessel and wall-mount faucets need a standard hole size?

Vessel faucets use the same 1-3/8″ single hole but sit tall to clear an above-counter bowl. Wall-mount faucets use no deck hole at all — they connect to rough-in plumbing in the wall, so hole size is irrelevant and your spacing is set by the valve body behind the wall instead.

Will a new faucet cover the old holes if I switch styles?

Often, yes. A single-hole faucet with a deck plate covers a 4″ three-hole layout cleanly. But a faucet base only spans so far — it won’t cover 8″ widespread holes if you drop down to a compact faucet. Match your new faucet’s coverage to your existing drilling, or plan to replace the sink.

A note on getting fitment right the first time

The reason hole size confuses people is that the number everyone asks about — 1-3/8″ — is the one thing that almost never varies. Spend your attention on hole count, center-to-center spacing, and deck thickness, and you’ll pick a faucet that drops in on the first try. Measure twice, buy once.

About the author & vevetta: This guide was written by the vevetta product content team and reviewed against manufacturer installation specifications and industry deck-drilling standards. vevetta designs and supplies bath and kitchen faucets, shower systems, and fixtures, and every faucet we ship includes a printed drilling template, gaskets sized to standard 1-3/8″ openings, and connection hardware. Our fixtures are pressure- and durability-tested to relevant plumbing performance standards, and they’re backed by our limited warranty — so when the spec sheet says “fits a 1-3/8-inch hole,” you can drill to it with confidence. When a measurement in this article differs from the template that ships in your box, follow the box.