How wide does the cooker hood need to be? This depends firstly on the width of the hob and secondly on the size of your kitchen. It is important for the hood to be slightly wider than the hob below it. Only then can you be certain of capturing all the rising steam and cooking vapours and benefit fully from the hood's power. If there is not enough space for this, then the hood should be at least as wide as the hob. Non-standard widths of up to 220 cm are possible for many models.