How to measure length, width and height
On a rectangular or oval table, length follows the longest outer edge and width crosses it at the widest point. On a round table, measure the diameter straight through the centre. Include any fixed rim, moulding or hardware that extends beyond the top.
Measure height vertically from the floor to the highest point of the tabletop—not the thickness of the top. Write the result as length × width × height in centimetres. If the floor or top is uneven, check more than one corner and record the largest useful measurement.
Record the measurements that decide whether chairs fit
Measure from the floor to the underside of the apron or any other low obstruction. Then measure the clear distance between the legs on every side where someone will sit. These figures reveal more about legroom than the tabletop size alone.
If the chairs have arms, compare their arm height with the table's underside. Also note the tabletop overhang: generous outer dimensions can still leave little usable seating width when the legs sit close together.
Measure it closed and fully extended
For an extending dining table, record the closed length and the maximum length with every included leaf or sliding section in place. Count separate leaves and note their individual size and where they will be stored.
Check whether the width, height or leg positions change as the table opens. Do not assume a listing's single measurement describes every configuration.
Test the table in the room
Mark the full tabletop footprint on the floor, then place the actual chairs around it and pull them back as they would be in use. This makes corners, radiators, doors and everyday walking routes much easier to judge than a floor plan alone.
Leave enough space for the real chair to move and for people to pass where a chair and a route share the same area. Test it in the room: no single clearance figure can account for every chair, table base and household.
Check the delivery route
Measure doors, stair turns, lifts and the narrowest landing. Establish which legs, bases or leaves can be removed safely before relying on a smaller delivery dimension.
Send the table measurements and the tightest route measurements to the seller or carrier before delivery. The smallest opening and the hardest turn decide whether the table can reach the room.