The hard part is not drawing it. It is that your measurements will not quite agree with each other, and a plan forces you to confront that in a way a list of numbers never does.
Room dimensions alone will not close into a plan. You need the connections between rooms as well, and those are the readings people skip.
For each room: length and width at both ends, both diagonals, and ceiling height. For the building: the overall external length and width, which is your check figure. And for every wall: the position of each door and window along it, measured from one corner, plus the width of the opening.
That last set is what turns a collection of rectangles into a usable plan. A room drawn without door positions cannot tell you whether furniture blocks a doorway or whether a wall can be removed.
Wall thickness matters too. Interior walls are commonly four to five inches with studwork and plasterboard, exterior walls considerably more. If you only measure room interiors, your rooms will not add up to the building.
Add up your interior room widths across a floor, add the wall thicknesses, and compare against the external measurement. It will not match.
This is normal and it is not a sign you measured badly. Walls are not perfectly uniform, rooms are not perfectly square, and small errors accumulate across a run. A discrepancy of one to two inches across a house is unremarkable. Four or five inches means something is genuinely wrong and worth finding.
The professional habit is to trust the overall external dimension as the controlling figure and distribute the discrepancy across the interior partitions, rather than trusting the interiors and letting the building grow. Your plan then closes, and the small error sits where it does the least damage.
The overall external length and width takes two readings and it is the only thing that tells you whether the rest of your numbers are consistent. Discovering a four inch discrepancy at the kitchen table, a week later, means going back.
Three routes, in increasing order of effort and precision.
Graph paper. Pick a scale where one square equals six inches or one foot, and draw the external outline first, then subdivide. The scale forces consistency and the external-first order means errors show up early rather than at the last wall. Perfectly adequate for planning furniture or a decorating job.
A floor plan app. Type in dimensions and it draws for you, handles wall thicknesses, and calculates areas as you go. The advantage is that most will tell you when a room does not close, which is a genuine check you do not get on paper. Several pair over Bluetooth with a laser measure so readings transfer without transcription, which removes the most common source of error in this whole process.
CAD. Overkill unless the plan is going to a builder or through planning. If it is, use it, because a scaled accurate drawing is what those processes expect.
If you are producing plans regularly, a tool that sends readings straight to an app removes hand transcription, which is where a surprising share of errors come from. Reading 14 ft 2 in and writing 14 ft 8 in is easy to do and impossible to spot later.
It is worth being realistic about the experience though. Owners of the Leica DISTO D1 describe the Bluetooth as unreliable and often unclear about whether a reading has actually synced, and thin documentation makes it worse. The feature is genuinely useful when it works. It is not yet the seamless thing the marketing suggests.
For occasional use, writing numbers onto a sketch as you take them is perfectly reliable and involves nothing that can fail to pair. The connected units are compared here.
Whichever route you take, draw the rough shape on paper before you take a single reading, and write each number onto that sketch as you go.
The plan gets made later, at a table. The sketch is what you make in the room, and it is the thing that records which wall each number belongs to. Without it you are left with a list of dimensions and a memory, and the memory is the part that fails. The room measuring method is here, and awkward shapes are covered separately.
Everything on LaserMeasure is built the same way, from owner reports rather than spec sheets. The front page is the summary.