Comparing square metres can help start a conversation, but a street does not make all properties the same. Even on the same block, orientation, floor, renovations, building and layout can alter the property's real appeal.
A metric needs context
The price per square metre is useful for beginning to organise references, but it does not replace analysis of a specific property.
Before using it, check whether the comparables share area, condition, exposure, lift, outdoor space and level of refurbishment.
The right question is competitive.
Rather than seeking an isolated figure, ask how your property will be positioned against the alternatives available when it goes on the market.
That answer allows you to decide the starting price, presentation and negotiation strategy with much greater clarity.