To measure a marble threshold, measure the width of the door opening jamb-to-jamb, then the depth of the gap between the two finished floors. Order the threshold at the jamb-to-jamb width (or up to 1/2″ wider if it will sit under the casing) and at least as deep as the gap. Standard thresholds run 24, 30 and 36 inches long, 3 to 6 inches wide, and 3/4 inch thick. If your opening is not a standard size, it gets cut to order.
What you need
- A steel tape measure (not a cloth one — fabric tapes stretch and 1/8″ matters here)
- A pencil and paper
- Five minutes
Step 1 — Measure the length (jamb to jamb)
Open the door fully. Measure the horizontal distance across the opening, from the inside face of one door jamb to the inside face of the other, at floor level. This is the length of your threshold — the long dimension.
Measure at floor level, not at waist height. Door frames are rarely perfectly square, and the floor is where the stone will actually sit. If the two measurements differ, use the larger one and plan to scribe or trim.
Most interior doors in US homes measure close to 30 or 36 inches across, which is why those are our two most common lengths (36-inch thresholds and 30-inch thresholds together account for most of what we ship).
Step 2 — Measure the width (the gap between floors)
Look down at the gap between your two flooring materials — say, tile on the bathroom side and hardwood on the hallway side. Measure the distance from the edge of one floor to the edge of the other. This is the width (sometimes called the depth).
The threshold must be at least as wide as that gap, and normally a little wider so it rests on the subfloor and overlaps both finished edges. In practice:
- 3″ and 4″ wide — standard interior doorways where the two floors meet closely
- 5″ and 6″ wide — wider transitions, shower curbs, and openings where the wall is thicker
If you are unsure, size up. A threshold that is slightly too wide can be scribed; one that is too narrow leaves a gap you cannot hide.
Step 3 — Check the thickness (height difference)
Measure the height of each finished floor. Our standard thickness is 3/4 inch, which suits the great majority of installations. If your two floors sit at noticeably different heights, you need a ramped or thicker threshold so the stone can bridge the step — that is a custom cut, not a stock item.
Step 4 — Choose the edge (bevel)
The bevel is the profile machined onto the long edge of the stone. It determines how the threshold meets the floor on each side.
- Standard bevel — a small chamfer on the edges. The default for a flush, floor-to-floor transition where both sides are level.
- Single Hollywood — one long edge is cut to a long, gentle slope. Use it when one floor sits higher than the other, so the slope faces the lower side. This is the usual choice for a bathroom doorway where tile sits above hardwood.
- Double Hollywood — both long edges sloped. Use it where the threshold sits proud of both floors, or for a shower curb that should shed water in both directions.
A gentle slope is not just cosmetic. A sloped (Hollywood) edge is what makes a raised transition easy to walk over and wheel across, which is why it is the profile that matters for ADA-compliant accessible routes.
Step 5 — Choose the finish
Polished is glossy and reflective; it shows the veining most vividly and wipes clean easily. Honed is a matte, satin surface; it hides scratches and water spots better and is less slippery underfoot — which is why it is often chosen for bathrooms and shower curbs.
Common sizes and what they cost
These are our most-ordered stock sizes, with the real price range across all stones (White Carrara through Black Absolute granite):
| Size (L × W × T) | Typical use | Price range |
|---|---|---|
| 36 × 6 × 3/4 in | Wide doorway, shower curb | $130 – $255 |
| 36 × 5 × 3/4 in | Standard 36″ doorway | $125 – $250 |
| 36 × 4 × 3/4 in | Standard 36″ doorway | $120 – $245 |
| 30 × 6 × 3/4 in | Wide 30″ opening | $119 – $235 |
| 30 × 4 × 3/4 in | Standard 30″ doorway | $110 – $225 |
| 24 × 4 × 3/4 in | Narrow openings, closets | from $65 |
All thresholds are 3/4 inch thick as standard. Prices vary by stone, not by finish or bevel.
What if my opening is not a standard size?
Then it gets cut to order. We fabricate at our own shop in Jersey City, NJ, so a non-standard length or width is a normal job rather than a special favour — custom marble thresholds are cut from the same slabs as the stock sizes. Send your measurements and we will quote it.
Frequently asked questions
Do I measure the door or the opening?
The opening. Measure jamb to jamb at floor level with the door open. The door slab itself is narrower than the opening and will give you a threshold that is too short.
Should the threshold run under the door casing or between the jambs?
Between the jambs is the simplest and the most common — cut to the jamb-to-jamb measurement. Running it under the casing looks more finished but means undercutting the trim and ordering the stone up to about 1/2 inch longer. Decide before you measure, not after.
How much extra should I allow?
For a between-the-jambs fit, order the exact jamb-to-jamb length; stone is cut accurately and a tight fit is what you want. Do not add a “safety margin” the way you would with timber — marble cannot be planed down on site without chipping the polished edge.
What thickness do I need?
3/4 inch covers nearly every standard installation and is what we stock. You only need something thicker or ramped if the two floors finish at clearly different heights.
Which bevel do I need if one floor is higher?
A Single Hollywood, with the slope facing the lower floor. That gives a gradual ramp instead of a hard step.
Polished or honed for a bathroom?
Honed. The matte surface is less slippery when wet and hides water spotting; polished is the better choice in a dry hallway or entryway where you want the veining to show.