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How to Set Scale on a Floor Plan
The scale step is where MeasureFloorPlan learns the real-world dimensions of your floor plan. Get this right and your square footage will be accurate. Here is exactly how to do it.
Why scale matters so much
MeasureFloorPlan sees your floor plan as a pixel image. It has no idea whether one inch on screen represents one foot or ten feet in the real world. The scale step is how you tell it. A 1% error in scale translates directly to roughly a 1% error in the final area calculation. Set the scale carefully and you will get accurate results.
Step-by-step: setting the scale
- After reviewing and approving the auto-detected perimeter, you will be prompted to set the scale.
- Click on one end of a wall you know the exact length of.
- Click on the other end of that same wall.
- Enter the real-world length of that wall in feet.
- MeasureFloorPlan will calculate the pixels-per-foot ratio and apply it to the entire floor plan.
Which wall to pick
The longer the wall you use for scale, the more accurate your result will be. A small click error on a long wall has minimal impact. That same click error on a short wall can skew the scale significantly.
- Pick the longest straight exterior wall you know the measurement of
- Use a wall that runs horizontally or vertically (not diagonal)
- Avoid short walls, bump-outs, and anything with curves
What if you don't know any wall length?
Most floor plans include at least some dimension notes: see how to read floor plan measurements for help finding them. If dimensions are not labeled, here are some fallbacks:
- Room dimensions: Many floor plans note room sizes like "12 x 14." Use the longer dimension of a room and click across the full width of that space.
- Door widths: Standard interior door openings are 2 feet 8 inches (2.67 ft). Standard exterior doors are 3 feet 0 inches (3.0 ft). These are consistent enough to use in a pinch, though a longer wall will give you better accuracy.
- CubiCasa, Matterport, iGUIDE: These services provide the total square footage in their reports. You can back-calculate scale by finding a labeled wall, or simply use a known room dimension from their report.
Common mistakes to avoid
- Wrong units: MeasureFloorPlan expects feet. If you enter meters or inches, your square footage will be way off. Convert before entering.
- Picking a diagonal wall: Diagonal walls are harder to click precisely from end to end. Use a straight horizontal or vertical wall whenever possible.
- Clicking inside the wall rather than at the edges: Click at the outer edges of the wall line, not in the middle of the wall thickness.
- Using an estimated measurement: If you are not sure of the exact length, find a wall you do know. An estimate introduces error from the start.