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Scan or draw: how do you start measuring your home?

The first choice is not which app or which tape measure — it is whether you can scan or have to draw. That is decided by the phone in your pocket, not by what you would prefer. The rest of the task falls into place once that is settled.

The first choice: scan or draw

Everything else about the task depends on this one question. LiDAR is a sensor that measures distance with light, and it only sits in newer iPhone Pro and iPad Pro models — not in ordinary iPhone and iPad models, and not in Android phones. If your phone has the sensor, an app can build a 3D model of the room as you walk around it, and work out measurements and areas from that model automatically. If it doesn't have the sensor, there is no shortcut: you have to take the measurements yourself with a tape measure or a laser distance meter and draw the rooms in afterwards.

Both routes end with a usable floor plan. The difference is the time it takes and how easy it is to do — not the quality of the end result, if you draw accurately.

How to check whether your phone can scan

Look at the model name, not at how new the phone is. LiDAR has been in the Pro models since 2020, but never in the ordinary models — so a phone from last year without "Pro" in its name still doesn't have it. The fastest way to check is to open an app that uses the sensor (a home measuring app, for instance) and see whether it offers scanning as an option. If it only offers drawing, the phone lacks the sensor.

How to prepare the home, whichever method you use

Both scanning and measuring with a tape are disrupted by the same things: furniture pushed up against the walls, doors left half closed, and clutter on the floor. Clear as much as you can away from the wall lines before you start — it doesn't need to look tidy, just clear of the edge. Open every door fully. And if there are pets or children in the home, it is easier to do one room at a time with the door closed behind you than to attempt it all in one go.

The same holds for drawing: you can draw more accurately when you can see the whole wall line and stand in the corners without having to move a sofa first.

The order that saves you doubling back

Start with the room that matters most for what the drawing will be used for. If it is to order a kitchen, start in the kitchen. If it is to sell the home, start with the living room and the rooms that count most in the listing. Then work your way through the rest, room by room, in the order the home actually connects — not jumping back and forth. That makes it easier to spot if two rooms don't fit together afterwards, for instance if a hallway ends up too narrow once both sides have been measured.

What you should know before choosing an accuracy level

A floor plan can be made quickly and roughly, or slowly and precisely — and how much time is worth spending depends entirely on the purpose:

• For your own overview and furnishing: centimetre precision is rarely necessary. A scan or a quick tape-measure pass is enough.
• For ordering contractors or furniture to size: here the millimetres count. Measure twice, and note where you measured from — the wall surface or the wall centre line gives different numbers.
• For a sale or official use: here it is often the public building register's area that counts legally, whatever you measure yourself. Your own drawing is a supplement, not a replacement.

How much time should you set aside?

An ordinary three- or four-room flat typically takes 15-30 minutes to scan, if the rooms are reasonably clear and you already know the app. The first time you use a scanning app, budget double the time — not because the scan itself takes longer, but because you stop and check as you go. Measuring by hand with a tape takes markedly longer: reckon on 15-25 minutes per room, once walls, door openings and window heights all have to be noted and drawn in afterwards. A five-room home can therefore take a whole afternoon with a tape measure against under an hour with a scan. That is the real price of not having LiDAR — not that the result is worse, but that it costs your time instead of the phone's sensor.

The most common starting mistakes

• Starting without a plan for the order. Jump back and forth between rooms and it's easy to forget one entirely, or measure the same door opening twice with a different result each time.
• Mixing outside and inside measurements without keeping them apart. A wall's outer length and its inner length are not the same figure — the difference is the wall's thickness times two. Mix them up and the room ends up with the wrong area.
• Assuming one scan captures everything. Tall cabinets, dark corners and furniture flush against the wall often hide the geometry behind them, however good the sensor is. Always check the result against reality before trusting the numbers.
• Putting off deciding the purpose. Know in advance that the drawing will go to a contractor, and you can take the extra measurements right away — instead of discovering three weeks later that you are missing the sill height of a window.

What a scan cannot do that a tape measure can

A LiDAR scan is fast, but not infallible. The sensor struggles with mirrors and large glass surfaces — it can "see through" them and place the wall behind in the wrong spot. Very narrow rooms, or rooms crammed with furniture, can produce a drawing that doesn't hang together correctly, because the app lacks enough data to understand the room's edges. In those cases a tape measure is still the more reliable tool, even if you scan the rest of the home.

What drawing with a tape requires that scanning does not

Conversely, measuring by hand requires you to remember to capture every dimension yourself — diagonals in irregular rooms, the height of sills below windows, the depth of alcoves. A scan captures most of that automatically, because it measures the whole surface, not just the points you choose to put the tape between. Forget a measurement with a tape and you won't discover it until the drawing is needed, and you have to go back to the home to measure again.

Can you start with one and switch to the other?

Yes. Many people start by scanning the rooms the phone can reach, and draw the rest in by hand afterwards — a loft with sloped ceilings full of boxes, or an outbuilding with no LiDAR access. All that's required is that both parts end up in the same drawing afterwards, at the same scale, so the two methods don't create a jump in accuracy in the middle of the plan.

What HouseSense does

When you create your first home in HouseSense, the app asks you directly whether you want to scan or draw — and only shows scanning as an option if your device actually has LiDAR. If it doesn't, or you prefer to measure it yourself, you draw the home on graph paper with your finger instead; that works on any iPhone or iPad. Both routes end up as the same kind of floor plan with measurements, areas and a 3D model afterwards, so the choice is only about how the data gets in — not what you can do with it afterwards.

How to start today

1. Check whether your device has LiDAR. The model name decides that, not the phone's age.
2. Clear the wall lines in the first room you plan to take — furniture flush against the wall disrupts both methods.
3. Choose the starting room by purpose, not by which room is easiest.
4. No LiDAR? Get a tape measure or a laser distance meter, and measure each wall twice.
5. Have LiDAR, but the room has mirrors or a lot of glass? Measure those walls yourself afterwards and correct the drawing — that is exactly where the sensor tends to fail.