January | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 30 Jan 1940 | U-15 | + | 25 | 25 | 0 | Accident |
| 30 Jan 1940 | U-55 | 42 | 1 | 41 | Aircraft & warship | |
February | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 5 Feb 1940 | U-41 | + | 49 | 49 | 0 | Warship |
| 12 Feb 1940 | U-33 | 42 | 25 | 17 | Warship | |
| 20 Feb 1940 | U-54 | + | 41 | 41 | 0 | Missing, lost to mines |
| 23 Feb 1940 | U-53 | + | 42 | 42 | 0 | Warship |
| 25 Feb 1940 | U-63 | 25 | 1 | 24 | Warship | |
March | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 11 Mar 1940 | U-31 | + | 58 | 58 | 0 | Air raid on port |
| 13 Mar 1940 | U-44 | + | 47 | 47 | 0 | Lost to minesWarship |
| 27 Mar 1940 | U-22 | + | 27 | 27 | 0 | Missing, lost to mines |
April | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 6 Apr 1940 | U-1 | + | 24 | 24 | 0 | Missing, lost to mines |
| 6 Apr 1940 | U-50 | + | 44 | 44 | 0 | Lost to mines |
| 13 Apr 1940 | U-64 | 46 | 8 | 38 | Aircraft | |
| 15 Apr 1940 | U-49 | 42 | 1 | 41 | Warship | |
May | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 31 May 1940 | U-13 | 26 | 0 | 26 | Warship | |
June | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 22 Jun 1940 | U-122 | + | 49 | 49 | 0 | Missing |
July | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 1 Jul 1940 | U-26 | 48 | 0 | 48 | Aircraft & warship | |
| 1 Jul 1940 | U-102 | + | 43 | 43 | 0 | Warship |
August | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 1 Aug 1940 | U-25 | + | 49 | 49 | 0 | Lost to mines |
| 20 Aug 1940 | U-51 | + | 43 | 43 | 0 | Warship |
September | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 3 Sep 1940 | U-57 | 25 | 6 | 19 | Accident | |
October | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 30 Oct 1940 | U-32 | 42 | 9 | 33 | Warship | |
November | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 2 Nov 1940 | U-31 | 46 | 2 | 44 | Warship | |
| 28 Nov 1940 | U-104 | + | 49 | 49 | 0 | Missing |
24 U-boats lost in 1940 (643 men died and 331 men survived those losses).
+ means that the boat was lost with all hands.
U-boats scuttled at sea after battle damage are considered war losses and are shown above.

