The key idea

A precise-looking scale is useful only when its real-world reference is correct.

Choose a distance you trust

Use a known dimension from a reliable drawing or an authorized measurement of the space. Choose endpoints you can identify clearly on the image. Avoid relying on the apparent size of a desk, door or furniture symbol when you do not know its actual dimensions.

A longer, clearly marked reference generally gives you more room to place endpoints accurately than a tiny feature. The best reference is one that another person could identify and verify, not merely the easiest line to click.

Place both endpoints carefully

Zoom enough to place the start and end on the intended boundaries. Check whether a printed dimension refers to the inside or outside of a wall and use the same interpretation at both ends. Enter the real-world distance in the stated unit.

Do not confuse the image’s screen size with its underlying pixel dimensions. Resizing a browser window should not change the real-world scale of the floor. Wi-Fi Master Planner calibrates uploaded images against their actual image dimensions.

Check the result against the space

After calibration, inspect another known portion of the plan as a sanity check. If the scale appears inconsistent, confirm the image was not stretched unevenly during export. A single scale cannot correct a drawing that has been distorted differently in each direction.

If the source is an informal sketch, be explicit about its limitations. It can still help people identify rooms and deliberate positions, but it should not be presented as a precise construction measurement.

Keep the coordinate reference stable

Complete calibration before the field visit and make sure the surveyor opens the intended floor version. If the image is replaced, verify its alignment and scale again. A new crop or changed aspect ratio can change how a position maps onto the picture.

When reviewing a report, inspect both the markers and familiar landmarks. If a point appears in a different room from the one surveyed, investigate the floor reference before interpreting the signal pattern.

Take it into the field

  • Use a verified distance with recognizable endpoints.
  • Check units and inside/outside wall references.
  • Avoid stretched or distorted source images.
  • Recheck calibration after replacing an image.

Put your next survey on the map.

Prepare a floor on the web, capture deliberate points on Android and review the observations in one place.

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