From [a previous answer] (https://www.reddit.com/r/AskHistorians/comments/4m56ss/why_were_the_allies_of_ww2_afraid_of_the_defences/d3szknw/) comparing Normandy to the Pas de Calais, with some added details for the Atlantic coast:
German defences in northern France were under Army Group B, broadly grouped into the Fifteenth Army (AOK 15) sector of the Pas-de-Calais and Upper Normandy (from Dunkirk to Le Havre, around 700km of coastline) and the Seventh Army (AOK 7) sector including Lower Normandy and Brittany (covering about 1500km of coastline).
Army Group G covered the south, with the First Army (AOK 1) sector covering the Atlantic coast from the Loire to the Spanish border (about 800km of coastline) and Nineteenth Army (AOK 19) covering the Mediterranean coast.
Steven J. Zaloga's The Atlantic Wall (1): France has a breakdown of artillery, bunkers and obstacles in the AOK 15, AOK 7 and AOK 1 sectors:
Artillery
AOK 15 had more guns than AOK 7 (670 vs 589) covering about half as much coastline, of heavier calibre (about 60% of AOK 7 guns were light (75-105mm) compared to 40% of AOK 15). There were several super heavy batteries in the Pas-de-Calais such as Lindemann, Grosser Kurfurst and Todt with guns of between 280mm and 406mm in heavy concrete casemates that could have fired on ships in the channel. AOK 1 had 391 guns, a slightly higher density per km than AOK 7 but much lower than AOK 15.
Bunkers
There were roughly similar numbers of bunkers in the two northern sectors (2,364 for AOK 15 vs 2,176 for AOK 7; Zaloga gives a further breakdown by type), again meaning more than twice the density of bunkers in AOK 15's sector due to the shorter coastline. AOK 1 had 1,566 bunkers, a slightly higher density than AOK 7 but lower than AOK 15.
Obstacles
Zaloga breaks down types of obstacle (stakes, concrete obstacles, 'hedgehogs', mines etc.) by Corps, with an overall obstacle density per km figure; for 67 Corps around Calais it was 705, for 84 Corps in Normandy it was 223, again less than half the density. In particular there were more than twice as many mines laid in the 67 Corps area. 80 Corps, covering the northern section of AOK 1 coastline, had the lowest density of all (105 per km).
Troops
The [Official History of the Canadian Army in the Second World War] (https://www.ibiblio.org/hyperwar/UN/Canada/CA/Victory/index.html) gives the Fifteenth Army 18 "non-mobile" divisions along the coast and the Seventh Army 11, again a substantially higher concentration in the Fifteenth Army sector (there's also a [map of their deployment] (https://www.ibiblio.org/hyperwar/UN/Canada/CA/Victory/sk/Victory-3.jpg)). The situation of the Panzer divisions in France was complicated by a disagreement between Rommel, who wanted them close to the beaches, and Rundstedt, who wanted to hold them back as a mobile reserve; as a compromise Rommel was given control of three, of which one was placed within striking distance of Normandy while the other two were north of the Seine. First Army had four "non-mobile" divisions and one Panzer division.
Zaloga has two further books on the Atlantic Wall covering Belgium, The Netherlands, Denmark, Norway and the Sudwall, but I'm afraid I haven't got those to provide figures.
