Pick a known line
Overall width, a wall length or a clearly identified door can work.
FREE FLOOR PLAN SCALE CALCULATOR
Turn one known measurement into a proportion-safe floor-plan scale.
Measure one line on the plan, enter its real size, and HausRay calculates one global scale. A second measurement checks whether the source image or the measurement is inconsistent.
Accuracy ruleSource proportions stay locked. Estimated dimensions remain visibly estimated.
LIVE CALCULATOR
Estimate one global floor-plan scale
Use one known line on your plan. Add a second independent measurement to check whether the image has been stretched.
Optional cross-check
1 source unit ≈ 1.7857 cm
321.4 cmRegional door values are low-confidence priors, not measurements. They may estimate global scale only.HOW IT WORKS
From source plan to a decision you can trust
Enter its real size
One anchor gives a uniform scale without changing the source shape.
Cross-check
A second measurement tests whether both dimensions agree with one global scale.
Keep conflicts visible
If they disagree, verify or rectify the source instead of stretching rooms.
HAUSRAY
Why a door can help when dimensions are missing
Residential openings are often more standardized than entire rooms, so a regional door prior can provide a useful first estimate. It remains low confidence and applies to the whole plan, not the door alone.
- Regional prior ≠ measurement.
- Use multiple openings where possible.
- Upgrade the estimate as soon as you obtain a real dimension.
HAUSRAY
A scale is not permission to redraw the floor plan
If the source says one room occupies 28% of the apartment width, metric conversion should preserve that relationship. Scale changes units; it should not redesign geometry.
FAQ
Questions people ask before trusting a floor plan
What if I only know one dimension?
One dimension can establish one uniform global scale. HausRay labels it single-anchor calibrated rather than pretending the entire source has been surveyed.
Can I use a typical door size?
Yes as a low-confidence regional prior. It is useful for exploration, but you should not treat it as a measured door or purchase-grade evidence.
Why not calculate separate X and Y scales?
Because that can silently change every room proportion. Separate-axis correction belongs to explicit whole-image rectification when the source itself is distorted.