Here is a tip to help you determine if you have measured your plans accurately
Once you have scaled your plans
In the "Plans and Take Offs" tab
Click the green "+" button to add a new measurement in the Take Offs section to the left
Rename the measurement "test"
Change the UOM to "lm"
Click the take off tool to start a new measurement
6. Choose the plan with measurements
7. Use the blue slider to zoom in on the plan
8. Draw along a measurement
9. Check the length of the line on the plan
10. This is the length of the line you have drawn, to then compare to the measurement in step 9