Draw any room shape - rectangular, L-shaped, angled, irregular - and get instant square footage, room dimensions and perimeter. Works for bedrooms, living rooms, kitchens and any space. Enter your room measurements and get exact results in sq ft or sq m, furniture fit suggestions, and paint and flooring estimates. Free, no signup, no limits.
⭐ 4.8/5 from 284 reviews · Used by homeowners, designers & contractors · Last updated June 6, 2026
⭐Used by 12,847 homeowners and pros this month
Click on grid dots to place walls and form any shape — rectangular, L-shape or irregular. Results appear here in real time.
Any shape, any room
From a 10×12 bedroom to an L-shaped open-plan living area — one tool, exact square footage.
Three steps - whether you need it as a room size calculator or a room dimension calculator.
Click dots on the grid to draw each wall in order. Close the shape by clicking your starting point. Works with any layout.
Click any wall and enter the actual length you measured. Decimals supported (e.g. 12.5 ft, 3.4 m). The drawing rescales automatically.
Square footage, perimeter, unit conversions and paint / flooring estimates appear in real time as you draw or edit.
For a rectangular room, multiply the length by the width:Area = Length × WidthA 12 × 15 ft room = 180 sq ft. For L-shaped or irregular rooms, split the shape into rectangles, calculate each area separately, then add them together - or just use the calculator above, which handles any polygon automatically.
L × W12 × 15 = 180 sq ftRectangle A + Rectangle B180 + 120 = 300 sq ft½ × Base × Height½ × 10 × 8 = 40 sq ftUse the calculator ↑Auto-calculatedBookmark this. It answers 95% of "what is X by Y in square feet?" questions.
| Dimensions | Sq Ft | Sq Meters |
|---|---|---|
| 8 × 10 ft | 80 sq ft | 7.4 m² |
| 10 × 10 ft | 100 sq ft | 9.3 m² |
| 10 × 12 ft | 120 sq ft | 11.1 m² |
| 11 × 13 ft | 143 sq ft | 13.3 m² |
| 12 × 12 ft | 144 sq ft | 13.4 m² |
| 12 × 14 ft | 168 sq ft | 15.6 m² |
| 12 × 15 ft | 180 sq ft | 16.7 m² |
| 14 × 16 ft | 224 sq ft | 20.8 m² |
| 15 × 20 ft | 300 sq ft | 27.9 m² |
| 16 × 20 ft | 320 sq ft | 29.7 m² |
| 20 × 20 ft | 400 sq ft | 37.2 m² |
| 20 × 25 ft | 500 sq ft | 46.5 m² |
Conversion: 1 sq ft = 0.0929 m² · multiply sq ft × 0.0929 to get sq m · multiply sq m × 10.764 to get sq ft
Follow these four steps to get room measurements you can confidently hand to a flooring installer, painter or AI room designer. This room size calculator works whether your room is a perfect rectangle, an L-shape, or something far weirder.
Stand at one corner and walk the room clockwise. As you go, click dots on the calculator grid to mark each wall. Don’t worry about scale - just get the shape right and close the polygon by returning to the starting dot. The grid is just a sketch surface; precision comes in step 3.
Use a tape measure or, ideally, a laser distance meter (~$25). Measure wall to wall, ignoring baseboards and trim, at floor level. Round to the nearest 0.1 ft (1.2 in) or 5 cm. For long walls, measure twice - small errors compound across multiple walls.
Switch to Edit mode, click each wall and enter the actual length. Decimals are fine (e.g. 12.5 ft, 3.4 m). The drawing rescales so the displayed shape and the math match your real room.
Before you order materials, glance at the total perimeter and compare to your tape readings. If it’s 5%+ off what you expect, you probably mis-clicked a wall. Double-checking here saves an entire return trip to the hardware store.
📐 Quick formula reminder: for a rectangular room, area = length × width. For everything else, the calculator uses the Shoelace formula automatically - no maths required.
Most online square-footage calculators are just a length × width form - fine for a perfect rectangle, useless the moment your room has an alcove, a bay window, an angled wall, or two zones connected by a hallway.
This room size calculator treats your room as a polygon. Click each corner in order, enter real wall lengths, and the area is computed by the same formula surveyors use - accurate for any closed shape, no matter how irregular.
✗ The slow way
Split the L into rectangle A and rectangle B. Measure four sides per rectangle. Calculate two areas. Add. Pray you didn’t double-count the overlap. Repeat for every irregular zone.
✓ With the calculator
Click corners. Type lengths. Done. Total area, perimeter and material estimates appear in real time - and stay accurate even if you change a single wall later.
Once the room size calculator gives you your number, compare it to standard room dimensions to spot a measuring mistake or to see whether a piece of furniture will feel cramped or comfortable.
200–250 sq ft
≈ 14 × 16 ft
Fits: King bed, two nightstands, dresser, sitting chair
120–150 sq ft
≈ 11 × 13 ft
Fits: Queen bed, one nightstand, small dresser
250–400 sq ft
≈ 16 × 20 ft
Fits: Sectional, coffee table, two armchairs, TV unit
150–200 sq ft
≈ 10 × 15 ft
Fits: L-shaped counter, island, full appliance suite
40–100 sq ft
≈ 5 × 8 to 8 × 12 ft
Fits: Tub or walk-in shower, vanity, toilet
150–200 sq ft
≈ 12 × 14 ft
Fits: 6–8 person table with chairs, sideboard
100–150 sq ft
≈ 10 × 12 ft
Fits: Desk, ergonomic chair, bookcase, filing cabinet
25–100 sq ft
≈ 5 × 7 ft typical
Fits: Hanging rods both sides, shoe shelving, island
240–280 sq ft
≈ 12 × 22 ft
Fits: One car, modest storage, workbench
Minimum room dimensions by bed size - the most searched bedroom sizing question, answered.
| Bed size | Min room dimensions | Min sq ft |
|---|---|---|
| Twin (38×75 in) | 8 × 10 ft | 80 sq ft |
| Full / Double (54×75 in) | 9 × 10 ft | 90 sq ft |
| Queen (60×80 in) | 10 × 11 ft | 110 sq ft |
| King (76×80 in) | 12 × 14 ft | 168 sq ft |
| Cal King (72×84 in) | 12 × 14 ft | 168 sq ft |
| Bunk bed (twin×2) | 8 × 10 ft | 80 sq ft |
Standard dimensions for every room type. Use these benchmarks alongside the calculator to check whether your measurements are in the right ballpark - or whether a bed, sofa or dining table will actually fit.
How big should a bedroom be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Small / guest bedroom | 100–120 sq ft | 10 × 10 – 10 × 12 ft |
| Standard bedroom | 120–150 sq ft | 11 × 12 – 12 × 13 ft |
| Large bedroom | 150–200 sq ft | 12 × 14 – 14 × 14 ft |
| Master / primary bedroom | 200–300 sq ft | 14 × 16 – 16 × 18 ft |
💡 Minimum for queen bed + walking space: 11 × 12 ft (132 sq ft). King bed needs 12 × 15 ft (180 sq ft).
How big should a living room be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Small living room | 130–170 sq ft | 11 × 13 – 12 × 14 ft |
| Standard living room | 180–240 sq ft | 12 × 15 – 14 × 18 ft |
| Large living room | 250–350 sq ft | 14 × 18 – 16 × 22 ft |
| Open-plan living area | 350–500 sq ft | 18 × 20 – 20 × 25 ft |
💡 Minimum for 3-seat sofa + coffee table + TV wall: 12 × 15 ft (180 sq ft). Allow 18" between sofa and table.
How big should a kitchen be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Galley kitchen | 70–120 sq ft | 7 × 10 – 8 × 15 ft |
| Standard kitchen | 130–200 sq ft | 10 × 13 – 12 × 16 ft |
| Large kitchen | 200–300 sq ft | 13 × 15 – 16 × 18 ft |
| Kitchen with island | 250–400 sq ft | 14 × 18 – 20 × 20 ft |
💡 Minimum aisle between counters: 42" (107 cm) for one cook; 48" for two. Island needs 42" clearance on all sides.
How big should a bathroom be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Half bath / powder room | 16–30 sq ft | 4 × 6 – 5 × 6 ft |
| 3/4 bath (shower only) | 36–50 sq ft | 6 × 6 – 5 × 10 ft |
| Full bath (tub + shower) | 40–80 sq ft | 5 × 8 – 8 × 10 ft |
| Master bath | 80–160 sq ft | 8 × 10 – 10 × 16 ft |
💡 ADA-accessible bathroom needs 60 sq ft minimum (5 × 12 ft) to accommodate a wheelchair turning radius.
How big should a home office be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Desk corner / alcove | 40–60 sq ft | 6 × 7 – 6 × 10 ft |
| Standard home office | 80–120 sq ft | 8 × 10 – 10 × 12 ft |
| Dual workstation | 130–180 sq ft | 11 × 12 – 12 × 15 ft |
| Office with client seating | 150–250 sq ft | 12 × 15 – 14 × 18 ft |
💡 Minimum for 60" desk + ergonomic chair + 36" bookcase: 80 sq ft (8 × 10 ft). Standing desks need ~60 sq ft clear.
How big should a dining room be?
| Type | Sq Ft | Dimensions |
|---|---|---|
| Dining for 4 | 100–130 sq ft | 10 × 10 – 10 × 13 ft |
| Dining for 6 | 130–170 sq ft | 11 × 12 – 12 × 14 ft |
| Dining for 8 | 160–220 sq ft | 12 × 14 – 14 × 16 ft |
| Formal dining room | 200–300 sq ft | 14 × 16 – 16 × 18 ft |
💡 Allow 36" (91 cm) between table edge and wall for seated diners to pull out chairs. 48" allows comfortable traffic.
Know your room size? Now see how it could look.
Upload a photo to Decoratly and see your room redesigned in 85+ professional styles - takes 30 seconds, free to try.
Two formulas, one rule each. The calculator converts between square feet and square meters automatically when you toggle units - but here’s the maths in case you need it on a job site.
Square feet → square meters
m² = ft² × 0.0929Example: 200 ft² × 0.0929 = 18.58 m²
Square meters → square feet
ft² = m² × 10.764Example: 25 m² × 10.764 = 269.1 ft²
| sq ft | sq m | What this is |
|---|---|---|
| 50 | 4.6 | Tiny bathroom |
| 100 | 9.3 | Small bedroom |
| 150 | 13.9 | Average bedroom |
| 200 | 18.6 | Master bedroom |
| 215 | 20.0 | 20 sq m room - common European apartment size |
| 220 | 20.4 | 220 sq ft room - spacious bedroom |
| 300 | 27.9 | Living room |
| 400 | 37.2 | Open-plan zone |
| 500 | 46.5 | Studio apartment |
| 1000 | 92.9 | Small house |
| 1500 | 139.4 | Average US home |
💡 A 20 m² room (~215 sq ft) is roughly the size of a generous US bedroom. A 220 sq ft room (~20.4 m²) fits a queen bed with comfortable clearance on all sides. Toggle the unit selector above and every result updates instantly.
Once you have area and perimeter, ordering materials becomes arithmetic. Below are the formulas the calculator uses internally - and the waste factors you should add before checkout.
Example: a 200 sq ft room with hardwood needs ~220 sq ft of product ordered.
Example: 48 ft perimeter × 8 ft ceiling = 384 sq ft → 1.1 gal per coat → 2 gal for two coats.
Example: 60 ft perimeter − 6 ft (two 36" doors) = 54 ft baseboard, order 60 ft.
Always factor in insulation, climate zone and sun exposure — these are starting points, not final specs.
Once you know square footage, contractor quotes become much easier to sanity-check. These are 2026 US national averages — expect 15–30% above for major metros, similarly below for rural areas.
Example: 200 sq ft engineered hardwood ≈ $1,800–$3,000 installed.
Example: a 12×14 ft bedroom professionally painted (walls + ceiling, two coats) ≈ $700–$1,400.
Use the room size calculator above to get your square footage first, then check these furniture clearance benchmarks - they'll tell you instantly whether a specific bed size, sofa or dining table will actually fit and feel right.
Needs 36" on three sides of the bed
24" clearance on each side
18" between sofa and table
36" clearance around table
Standing desk needs 60 sq ft
ADA clearance needs 60 sq ft
Crib + dresser + nursing chair
Treadmill + mat + bench
Armchair + side table
Not sure if your room is big enough?
Use the calculator above to get your exact square footage, then take your room photo to Decoratly's AI designer to see how different styles and furniture arrangements would actually look - before you buy anything.
Lessons from interior designers, contractors and the homeowners who saved themselves a costly second hardware-store run.
Walls aren't always perfectly vertical - older homes can be ¾ inch off plumb. Always pull your tape along the floor, the surface that flooring and baseboards actually touch.
Note the swing direction of every door. Some flooring (like thick hardwood) can prevent doors from closing - you may need to plane the door bottom or remove transition strips.
Beyond the % waste factor, keep one full box for future repairs. Dye lots change between production runs and you may not match the color years later.
Tape measures sag and mis-read past 12 ft. A $25 laser meter (Bosch or Leica) is accurate to ⅛ inch over 50 ft and pays for itself in one project.
Include outlets, switches, vents and trim profiles in the photos. You'll thank yourself when the contractor or designer asks 'is there an outlet there?' three weeks later.
Rectangular calculators handle one situation. Real homes have alcoves, L-shapes and angled walls. Here’s the side-by-side.
This calculator was built by the Decoratly team - creators of AI interior design tools used by 500,000+ homeowners to visualise and plan their spaces. We built it because every room-planning project starts with one question: how big is this room, exactly?
The area engine uses the Shoelace formula (also called the Gauss area formula) - the same mathematical method used in surveying software and GIS mapping. It computes the exact area of any closed polygon from its vertex coordinates, accurate to floating-point precision with no rounding until the final display.
Everything runs entirely in your browser. No room sketches are sent to a server, no data is stored, no account is needed. Refresh the page and the canvas clears completely.
Area: Shoelace polygon formula - exact for any closed shape. Perimeter: direct sum of wall segment lengths. No approximations, no rounding until display.
The calculator is only as accurate as the measurements you enter. Always measure wall-to-wall at floor level. Use a laser distance meter for walls longer than 15 ft.
Content and all room-size benchmarks reviewed June 2026. US room-size data sourced from NAHB (National Association of Home Builders) annual reports.
No account needed, no cookies set, nothing stored server-side. Your room drawing exists only in your browser's memory and clears when you leave.
Homeowners ordering flooring or paint, interior designers briefing clients, contractors verifying measurements, and real-estate agents preparing listings.
Once you know your square footage, the next question is what to do with it. Browse 15 designer-curated AI interior design styles and see exactly how each one would transform a room of your size - from cosy farmhouse to high-gloss glam.
Light, airy, hygge
Clean lines, bold accents
Less is more
Layered, eclectic, warm
Brick, steel, edison bulbs
Shiplap, barn doors, comfort
Beachy, blue, breezy
Walnut, geometry, retro
Brass, drama, geometry
Of-the-moment, refined
Classic meets modern
Reclaimed wood, stone
Velvet, mirrors, gold
Curated mix of eras
Distressed, floral, soft
Upload one photo · pick a style · get a redesigned room in seconds
Everything homeowners, designers and contractors ask before trusting a square-footage tool with a real project.
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