Understanding your result
The headline is the number of rows across the room, with a line beneath it that says whether the first and last rows are ripped. The stats give the planks per row, the last-row width and the stagger offset, and the plan below draws the rows and end joints to scale so you can see the pattern before you lay it.
Start with width available after the gaps: the room width less the expansion gap at both walls. That is the space the planks must fill. Divide it by the plank width and you get the full rows and a leftover. If the leftover is at least the minimum you set, it is simply the last row. If it is less, the calculator rips the first row and the last row to the same width, half of a full plank plus the leftover, so neither edge is a sliver. If the leftover passes your minimum but is less than half a plank, the note suggests the same balancing as an option, because a 2 in row against the far wall is legal but looks odd from the door.
Planks per row is the room length divided by the plank length, rounded up, because the row ends in a cut. The stagger is a third of a plank when that is at least your minimum offset, otherwise half a plank. Thirds look more natural; halves are the fallback for short planks. For the boxes these planks come in, use the laminate calculator or the vinyl plank calculator; for the gap you entered, the expansion gap calculator gives the right figure for each material.
How we calculate this
The plank width is the face width, the part you see once the planks are clicked together; the tongue disappears into the next board. The ripping rule is the one installers use: take one full row out of the count, add its width to the leftover, and share the total between the two edge rows. The same arithmetic for tile, which has joints but no stagger rule, is on the tile layout calculator. The guide to plank direction and the last row walks through how to snap the first line, and the standard sizes reference lists common plank widths and lengths.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Plank | 7.5 × 48 in (19 × 120 cm) | A common laminate and LVP size (Pergo Outlast+ is 7.5 × 47.6 in) |
| Expansion gap | 3/8 in (10 mm) at each wall | Typical laminate installation instructions; 1/4 in for vinyl plank, 3/4 in for solid wood |
| Minimum last row | 2 in (5 cm) | Common manufacturer minimum for click profiles; some allow 1.5 in |
| Minimum stagger | 6 in (15 cm) | Common manufacturer minimum for click plank; wood makers often ask 8 to 12 in |
| Stagger pattern | thirds, else halves | Installer practice; thirds avoid the brick look of halves |
Assumptions last reviewed October 8, 2026.
The calculator assumes parallel walls. A room that is 1/4 in wider at one end than the other turns an exact fit into a tapering sliver; measure the width at both ends and use the narrower figure, then check the wider end against the same arithmetic. It does not handle doorways that the planks run into, hallways that change the row count, or a room the planks turn through. And the stagger it proposes is a starting rule, not a pattern to repeat mechanically; the note under the result says why. The expansion gaps guide explains why the gap comes off before anything else.
Two worked examples
A 14 × 18 ft living room in 7.5 × 48 in laminate
Planks run along the 18 ft length, 3/8 in gaps, 2 in minimum last row, 6 in minimum stagger.
- Available: 14 ft = 168 in − 0.75 in = 167.25 in
- Full rows: 167.25 ÷ 7.5 = 22.3, so 22 rows with 2.25 in left
- 2.25 in passes the 2 in minimum: 23 rows, last row 2.25 in
- Planks per row: 216 ÷ 48 = 4.5, so 5 with a cut; stagger 48 ÷ 3 = 16 in
It is legal, but a 2.25 in strip along one wall of a living room shows. The note suggests ripping the first row to (7.5 + 2.25) ÷ 2 = 4.875 in, giving two matching edges at the cost of one extra rip cut.
An 11 × 13 ft bedroom in 5 × 36 in vinyl plank
Planks along the 13 ft length, 1/4 in gaps, 2.5 in minimum last row.
- Available: 132 − 0.5 = 131.5 in
- Full rows: 131.5 ÷ 5 = 26.3, so 26 rows with 1.5 in left
- 1.5 in is under 2.5 in: rip the first and last rows to (5 + 1.5) ÷ 2 = 3.25 in, 27 rows
- Planks per row: 156 ÷ 36 = 4.3, so 5; stagger 12 in
Without the rip the far wall gets a 1.5 in sliver that the click profile can barely hold. With it, both edges are 3.25 in and nobody can tell which wall the floor started from.
Where to find your inputs
Room width and length. Width is measured across the planks, length along them. Measure the width at both ends of the room and use the smaller figure.
Plank width and length. On the carton. Use the face width, which is the visible width once clicked together; the product page usually gives it.
Expansion gap. From the installation instructions: 1/4 in for most vinyl plank, 3/8 in for laminate, 3/4 in for solid wood.
Minimum last row and stagger. From the instructions, which state both. If they do not, 2 in and 6 in are safe.
Common mistakes
- Starting with a full plank because it is easier. The far wall gets the leftover. Work it out first.
- Forgetting the gap in the arithmetic. The planks fill the room less two gaps, not the room.
- Measuring one end of the room. Walls are rarely parallel. Measure both ends.
- A stair-step stagger. Repeating the same offset every row makes a visible diagonal. Vary the starting piece.
- End joints too close. Joints in adjacent rows closer than the minimum weaken the floor and void the warranty.
- Using the nominal width with the tongue. The face width is what counts for rows.
Questions people ask
- How do I work out the width of the last row of flooring?
- Subtract the expansion gaps from the room width, divide by the plank's face width, and the remainder is the last row. A 12 ft room with 3/8 inch gaps leaves 143.25 inches; 7.5 inch planks fill 19 rows (142.5 inches) and leave a 0.75 inch last row, which is too narrow to lay.
- Should I rip the first row of flooring?
- Rip it when the last row would be narrower than about 2 inches, or narrower than the maker's minimum. Add the leftover to a full plank width and halve it, then rip both the first and last rows to that width. In the 12 ft example, both edge rows become 4.125 inches and the room looks balanced.
- What is the minimum width for the last row of laminate or LVP?
- Most makers say 2 inches (5 cm), some 1.5 inches; check the carton. Below that the locking profile has too little to hold. Many installers aim for at least a third of a plank for looks, which on 7.5 inch plank is about 2.5 inches.
- How much should the end joints be staggered?
- Manufacturers require at least 6 to 12 inches between end joints in adjacent rows; 6 inches is the common minimum for click plank, 8 to 12 for wood. A thirds pattern on a 48 inch plank gives 16 inch offsets. Vary the starting piece so the joints do not form a visible staircase.
- Which way should the planks run?
- Usually along the longest wall or toward the main light source, so the joints are less visible and the room looks longer. Over a joisted floor, solid wood runs across the joists. The guide on plank direction covers the cases where the rule bends.
- Does the calculator tell me how many boxes to buy?
- No, it lays out the rows. The count of planks it gives is the number you will handle, before waste. For boxes, use the laminate, vinyl plank or hardwood calculator with the same room, which adds the waste for your layout.