There were a number of considerations in selecting the lodgement area for the invasion: air, naval, strategic and logistic.

From an air perspective the lodgement area had to be within range of air forces based in the UK (primarily the south-east), setting a western limit of Cherbourg and an eastern limit of Flushing. From a naval perspective it was highly desirable to operate in the English Channel between Cherbourg and Calais; this area minimised the risk from German mines, submarines and surface units. Operations east of Calais into the North Sea would not have been impossible, but would have required a much heavier minesweeping and defensive naval effort. Strategically the lodgement area could not be too heavily defended by German forces and had to be immediately defensible following the landing, but had to offer the ability to launch offensive operations after landing. Logistically it had to be possible to supply and maintain a force of 30 divisions, initially over beaches as the Dieppe raid had shown the impossibility of immediately capturing a port; that meant not just landing the supplies, but also transporting them inland from the beaches.

Studying the beaches from Cherbourg to Flushing, the Dutch beaches were considered unsuitable due to limited road exits, an insufficient tide range for "drying out" (grounding a ship at high tide and unloading onto dry sand as the tide goes out) and exposure to prevailing winds. The Belgian beaches were also exposed to prevailing winds and strong currents, and backed by extensive sand dunes. Combined with the increased difficulties in naval operations east of Calais, the logical choices were therefore either the Pas de Calais or the Cotentin-Caen area. The former had the advantage of being the closest point to the UK, but as a result was the most heavily defended by the Germans, hence the selection of the latter.