Rug Size Calculator
Rug dimensions and area from room and border.
What it does
Rugs frame rooms with floor showing around them. Subtract twice the border from each room dimension and the remainder is the rug. This page runs that subtraction in feet or meters with area beside it.
The default is a 12 by 15 ft room with 18 in showing. Each side loses 3 ft total, leaving a 9 by 12 ft rug with 108 ft2. Metric defaults convert the same room to 3.66 by 4.57 m with 46 cm and give 2.74 by 3.65 m with 10 m2.
Border is taste plus doors. Twelve inches suits small rooms, eighteen centers living sets, and twenty four airs out large spaces, while doors need clearance to swing over pile. Tape the outline on the floor before buying.
Stock sizes rule buying. Raw math rarely lands on 8x10 or 9x12 exactly, so round down to the nearest standard rug and center it rather than squeezing wall to wall.
How to use
- Pick imperial or metric first.
- Enter room length and width.
- Enter border showing per side.
- Read rug size first.
- Round down to stock sizes.
Formula
- room L
- Room length in the active units.
- room W
- Room width in the active units.
- border
- Floor showing per side.
Border is floor showing per side, so twice per dimension. Standard rugs come in fixed sizes, so round the raw result down to the nearest stock size and center it. Metric converts 1 in to 2.54 cm behind the scenes.
Worked example
Example: 12 by 15 ft room
12 by 15 ft room, 18 in border (metric 3.66 by 4.57 m, 46 cm).
- Length: 12 - 2 x 18/12 = 12 - 3 = 9 ft.
- Width: 15 - 3 = 12 ft.
- Rug: 9 x 12 ft.
- Area: 9 x 12 = 108 ft2.
- Metric: 3.66 by 4.57 m with 46 cm gives 2.74 by 3.65 m.
- Tool shows 9 x 12 ft imperial.
Reference table
| Room | Rug | Area |
|---|---|---|
| 10 x 12 ft | 7 x 9 ft | 63 ft2 |
| 11 x 14 ft | 8 x 11 ft | 88 ft2 |
| 12 x 15 ft | 9 x 12 ft | 108 ft2 |
| 14 x 18 ft | 11 x 15 ft | 165 ft2 |
| 16 x 20 ft | 13 x 17 ft | 221 ft2 |
Limits
- Rectangles only. Rounds and runners differ.
- Ignores doors, vents, and furniture fit.
- Stock sizes need rounding down.
- One border per pass. Uneven reveals need splitting.
Common mistakes
- Subtracting border once instead of twice.
- Mixing inches with feet mid chain.
- Ordering raw size with no stock check.
- Forgetting door clearance over pile.
- Sizing to walls instead of seating.
Try it yourself
Quick checks. Answers sit tucked under each question.
12 by 14 ft room, 24 in border?
8 by 10 ft (12 - 4 by 14 - 4 at 24 in border), 80 ft2.
9 by 12 ft room, 18 in border?
6 by 9 ft at 18 in border (9 - 3 by 12 - 3).
Questions
What rug size?
Room minus twice the border each way. Here 9 by 12 ft.
Rug area?
Length times width. Here 108 ft2.
What is that in metric?
2.74 by 3.65 m with 10 m2.
What border?
Often 12 to 24 in of floor showing. Here 18 in.
Doors included?
Yes for planning, but doors need clearance over pile.
Round rugs?
No. Shape, pattern repeat, and pads sit outside size math.