A simple tape measure will work fine. But make sure not to forget about wall thickness.
For an exterior an inch or 2 of accuracy is fine, but for interiors you should try to be accurate to around 1/4 or 1/8 inch (.5 cm).
It doesn't take as long as you might think, especially if you have a helper.
Make a rough floor plan (on paper), then measure and mark each wall on the plan.
Then enter all that into the program, and just stare at it - make sure it looks right. (It's far too easy to mess up, or not do the wall thickness right.)
Then go back and measure the location of doors and windows (including height, and offset from the floor). Put all that in.
Resist the urge to put in furniture until you are mostly done.
If you have multiple levels things will be more complex - you will need to know floor thickness, and ceiling height.
For an exterior an inch or 2 of accuracy is fine, but for interiors you should try to be accurate to around 1/4 or 1/8 inch (.5 cm).
It doesn't take as long as you might think, especially if you have a helper.
Make a rough floor plan (on paper), then measure and mark each wall on the plan.
Then enter all that into the program, and just stare at it - make sure it looks right. (It's far too easy to mess up, or not do the wall thickness right.)
Then go back and measure the location of doors and windows (including height, and offset from the floor). Put all that in.
Resist the urge to put in furniture until you are mostly done.
If you have multiple levels things will be more complex - you will need to know floor thickness, and ceiling height.