A floor plan is a scaled, top-down drawing of a space: walls, doors, windows and rooms, with dimensions. You don't need CAD training to draw one — you need accurate measurements, a consistent scale, and a tool that keeps your lines straight. This guide walks through the whole process. The examples use Gridsnap, a free floor plan creator that runs in your browser with no sign up, but the method applies on paper too.
Step 1: Measure the space
Everything downstream depends on the measurements, so take them properly:
- Measure wall to wall at floor level, not along skirting boards or window sills — they stick out and will skew your plan.
- Work room by room and sketch each one roughly as you go, writing lengths directly on the sketch.
- Note every opening: for each door and window, record its width and its distance from the nearest corner.
- Record wall thickness where you can see it (door frames are the easiest place) — typically 100–150 mm for interior walls and 250–400 mm for exterior walls.
- A laser distance measure is faster and more accurate than a tape for anything over a couple of metres.
Already have an old plan or a sketch? You can skip re-measuring: Gridsnap's trace mode lets you import a photo or scan, calibrate its scale against one known length, and draw over it.
Step 2: Pick a scale and units
On paper, you'd choose a scale first — commonly 1:50 (1 cm on paper = 50 cm in reality) for single rooms or 1:100 for a whole home. In an online editor this decision moves to the end: you draw in real-world dimensions (millimetres in Gridsnap) and choose the print scale at export time. Either way, know your target sheet — a typical house fits on A4 at 1:100 and on A3 at 1:50.
Step 3: Draw the exterior walls first
Start with the outline of the building, not the interior. In Gridsnap: click where a wall starts, type the exact length, press Tab to enter an angle if you need one, and hit Enter — the wall lands at exactly that dimension. Work your way around the perimeter until the outline closes; the snap engine catches the starting corner so the loop closes perfectly.
If you're planning a new build from lot dimensions rather than measuring an existing space, do the same thing in reverse: draw the buildable rectangle first (say, 15 × 9 m — or 50 × 30 ft converted to metres), then design inside it.
Step 4: Add interior walls
Interior walls are all about position: a wall usually starts at a known offset from a corner ("the bathroom wall is 600 mm from this corner"). On paper you'd measure and mark that offset; in Gridsnap you hover the corner to acquire it as a reference point, type the offset, and start the wall exactly there. Keep walls orthogonal unless the building genuinely has angles — casually drawn walls are automatically straightened.
Step 5: Place doors and windows
Doors and windows live inside walls, so don't draw them as separate lines. Place a door on a wall and it cuts its own opening; the swing arc — the quarter-circle showing which way the door opens — is drawn for you, no protractor or compass needed. Use your measured corner-to-opening distances to position each one, and pick the right type: single, double or sliding. Windows snap flush into the wall the same way.
Check door swings early. A door should open against a wall, not into the walking path or against furniture. It's the most common mistake on amateur plans — and the cheapest one to fix while it's still a drawing.
Step 6: Stairs and additional floors
If your building has more than one storey, finish the ground floor first, then add floors above — or below, for a basement. Stairs in Gridsnap are parametric: choose straight, L-shaped or U-shaped, and the stairwell opening is cut automatically in the floor above. While drawing an upper floor, a ghost of the floor below shows through so you can line up walls and stack the staircase in the same position.
Step 7: Label rooms and add dimensions
A plan without dimensions is a sketch. Add a dimension chain along each façade and any internal measurement a builder would need. In Gridsnap, dimensions anchor to the geometry — corners, door jambs, window jambs — and update automatically when you move a wall. Rooms are detected from the walls with one click and labelled with their net floor area in m², measured to the inner wall faces the way a surveyor would.
Step 8: Add furniture (optional)
Furniture turns a technical drawing into a layout you can evaluate: does the bed leave room to walk? Does the sofa block the door swing? Use real dimensions — a double bed is roughly 1600 × 2000 mm, a sofa seat about 900 mm deep. Gridsnap's furniture catalog is parametric, so every item resizes to exact dimensions and snaps flush against walls.
Step 9: Print, export or share it
Export the finished plan as a vector PDF at a standard scale — 1:50, 1:100 or 1:200 on A4 to A2 — and it prints true to scale, measurable with a scale ruler, with a title block, scale bar and room schedule. Handing it to a professional? A layered DXF opens cleanly in AutoCAD and ArchiCAD. For a quick share in a chat or email, export a PNG.
Common mistakes to avoid
- Ignoring wall thickness. Drawing walls as thin lines makes rooms look bigger than they are — a 4 m room loses ~300 mm to the walls around it.
- Measuring over skirting and sills instead of wall face to wall face.
- No dimensions. If someone has to measure your drawing with a ruler and guess the scale, it won't survive contact with a builder.
- Doors drawn without swing arcs — you won't spot collisions between doors, walls and furniture.
- Forgetting what's above and below — stairs need an opening in the floor above, and load-bearing walls should stack.
Start drawing
That's the whole method: measure carefully, draw the shell, work inward, dimension everything, print to scale. The Gridsnap editor is free, runs in your browser, and needs no account — your plan stays on your device. Rather not start from an empty grid? Open one of the free floor plan templates and edit it instead. Prefer the pen-and-paper route first? See our companion guide on drawing floor plans on graph paper.