Understanding your result
The headline is the height difference, with the recommended transition beneath it. The stats give each floor’s total thickness and the build-up that would level them; the table names both floors, the difference, which side is higher, the transition and the build-up.
Each floor’s thickness is the typical figure for the flooring plus its own setting bed or underlayment, plus any extra build-up you entered, such as underlayment plywood, leveler or a heating mat. The difference is the gap between the two. The transition follows the thresholds in the accessibility standards: up to 1/4 in, a T-moulding or low reducer; 1/4 to 1/2 in, a bevelled reducer; 1/2 to 3/4 in, a ramp threshold or building up; over 3/4 in, build up first.
The build-up row tells you how much to raise the lower floor to bring them level, which is usually the better fix for anything over 1/2 in. Underlayment plywood comes in standard thicknesses that the subfloor plywood calculator counts; fractions of an inch are what the self-leveling compound calculator is for. The strips themselves, by doorway and type, are on the thresholds and transitions calculator.
How we calculate this
The thresholds are from the 2010 ADA Standards for Accessible Design, section 303 (changes in level), which the International Building Code references for accessible routes. The thicknesses are typical product figures, listed in the table on the standard sizes reference; your products may differ by a millimetre or two. The expansion gaps guide explains why floating floors need a gap under the transition, and the self-leveling guide covers raising a floor by fractions of an inch.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Tile on thinset | 1/2 in (3/8 in tile + 1/8 in mortar) | Typical porcelain floor tile and a 1/4 × 3/8 in notch bed |
| Tile on 1/4 in cement board | 7/8 in | Tile, mortar, board and its thinset bed |
| Solid hardwood | 3/4 in | Standard solid strip and plank |
| Laminate | 12 mm plus 2 mm underlayment, about 0.55 in | Common laminate products |
| Vinyl plank | 6 mm with attached pad | Common rigid-core LVP |
| Carpet | about 3/4 in compressed | Carpet and a 7/16 in pad |
| Thresholds | 1/4 in vertical, 1/2 in bevelled, over 1/2 in a ramp | 2010 ADA Standards, section 303 |
Assumptions last reviewed October 8, 2026.
The calculator does not measure the existing floor; an old floor may have settled or have extra layers. Pull a threshold or a floor vent cover to measure the real build-up. It does not model the door: a raised floor may need the door trimmed to clear it. It also treats carpet by its compressed height, which is what the transition sees.
Two worked examples
Tile meeting solid hardwood
Porcelain on thinset (1/2 in) against 3/4 in hardwood.
- Floor A: 0.5 in; floor B: 0.75 in
- Difference: 1/4 in, hardwood higher
- Transition: a T-moulding or low-profile reducer
A quarter inch is the limit for a plain step; a reducer made for wood-to-tile tidies it and protects the end grain. If the tile were on cement board instead, the floors would be within 1/8 in of each other.
Hardwood meeting glue-down vinyl tile
3/4 in hardwood against 3 mm vinyl tile.
- Floor A: 0.75 in; floor B: 0.12 in
- Difference: 0.63 in, hardwood higher
- Transition: ramp threshold, or build up the vinyl side by about 5/8 in
A 5/8 in step at a doorway is a trip hazard. A 1/2 in underlayment plywood under the vinyl leaves an eighth of an inch, which a T-moulding hides; it costs a few sheets and makes the doorway safe.
Where to find your inputs
The two floors. From the product specification sheets, which give the overall thickness. Choose custom if yours differ from the typical figures.
Extra build-up. Underlayment plywood, leveler, a heating mat or membrane under either floor.
The existing floor. Measure at a doorway, a vent or a threshold, where the edge is visible.
Common mistakes
- Comparing the flooring alone. Underlayment, mortar and pad are part of the height.
- A tall transition instead of building up. Over 1/2 in, raise the low floor.
- Fixing the strip through a floating floor. It pins the floor. Fix it to the subfloor or a track.
- Forgetting the door. A raised floor may need the door cut down.
- Ignoring the carpet’s compression. Carpet sits lower than its pile height.
- Leaving no gap under the strip. Each floating floor needs its expansion gap.
Questions people ask
- How do I deal with a height difference between two floors?
- Work out each floor's total thickness including what is under it, and compare. Up to 1/4 inch, a T-moulding or low reducer works; 1/4 to 1/2 inch, a bevelled reducer; over 1/2 inch, a ramp or, better, build up the lower floor with underlayment or leveler so the difference is small.
- How thick is tile compared with laminate?
- Porcelain tile on thinset is about 1/2 inch, and on cement board nearly 7/8 inch. Laminate on its underlayment is about 0.55 inch, vinyl plank with a pad about 1/4 inch, and solid hardwood 3/4 inch. Product specification sheets give the exact figures.
- What height change is allowed at a doorway?
- The ADA standards (section 303) allow a vertical change up to 1/4 inch, a bevelled change up to 1/2 inch at a slope no steeper than 1:2, and treat anything over 1/2 inch as a ramp. Homes are not always required to meet them, but they are a good guide to what is safe.
- How do I raise a floor to match another?
- Underlayment plywood comes in 1/4, 3/8, 1/2 and 5/8 inch, and can be combined; self-leveling compound fills fractions of an inch. Raising the low side is often better than a tall transition.
- Do transition strips go over a floating floor?
- They sit over the gap between the floors and are fixed to the subfloor or to a track, never through the floating floor itself, so it can still move. Each floor keeps its own expansion gap under the strip.
- What transition goes between carpet and hard floor?
- A carpet edge, Z-bar or carpet-to-tile reducer that grips the carpet and steps down to the hard floor. Carpet compresses, so its effective height is less than its pile; about 3/4 inch for carpet and a 7/16 inch pad.