<PAGE>   1
                                                                EXHIBIT 11


                                NTL INCORPORATED

                       CALCULATION OF NET (LOSS) PER SHARE

<TABLE>
<CAPTION>
                                                                                  Weighted Average Number of Shares
                                                         ---------------------------------------------------------------------------
        Date           Description                          Total        Year Ended       Year Ended      Year Ended     Year Ended
       Issued          of Issuance                       Outstanding      31-Dec-98       31-Dec-97       31-Dec-96      31-Dec-95
------------------------------------------------------------------------------------------------------------------------------------
<S>                   <C>                              <C>             <C>             <C>             <C>             <C>
      12/31/94        Common Stock                        30,180,114      30,180,114      30,180,114      30,180,114     30,180,114
      01/01/95        Common Stock                                20              20              20              20             20
      01/12/95        Common Stock                               200             200             200             200            193
      02/02/95        Common Stock                             2,075           2,075           2,075           2,075          1,887
      02/23/95        Common Stock                               556             556             556             556            474
      04/04/95        Common Stock                             1,333           1,333           1,333           1,333            990
      06/08/95        Common Stock                             2,667           2,667           2,667           2,667          1,505
      08/04/95        Common Stock                               200             200             200             200             82
      08/07/95        Common Stock                               417             417             417             417            167
      08/21/95        Common Stock                               156             156             156             156             56
      09/05/95        Common Stock                            13,333          13,333          13,333          13,333          4,274
      02/13/96        Common Stock                             2,223           2,223           2,223           1,956
      02/22/96        Common Stock                               533             533             533             456
      02/28/96        Common Stock                             4,919           4,919           4,919           4,126
      03/06/96        Common Stock                             1,133           1,133           1,133             929
      03/12/96        Common Stock                             5,925           5,925           5,925           4,759
      03/20/96        Common Stock                             3,450           3,450           3,450           2,696
      03/25/96        Common Stock                            75,000          75,000          75,000          57,582
      04/11/96        Common Stock                            10,419          10,419          10,419           7,515
      04/26/96        Common Stock                            25,000          25,000          25,000          17,008
      05/30/96        Common Stock                             1,333           1,333           1,333             783
      06/13/96        Common Stock                           128,793         128,793         128,793          70,731
      06/14/96        Common Stock                           132,000         132,000         132,000          72,131
      08/29/96        Common Stock                         1,415,000       1,415,000       1,415,000         599,249
      11/06/96        Common Stock                                44              44              44               7
      11/25/96        Common Stock                             1,112           1,112           1,112             109
      12/26/96        Common Stock                             5,500           5,500           5,500              75
      12/27/96        Common Stock                             2,000           2,000           2,000              22
      12/31/96        Common Stock                            50,667          50,667          50,667               0
      01/14/97        Common Stock                             1,000           1,000             962
      01/17/97        Common Stock                             4,489           4,489           4,280
      01/21/97        Common Stock                            23,332          23,332          20,914
      02/06/97        Common Stock                               223             223             183
      03/26/97        Common Stock                             1,500           1,500           1,151
      05/30/97        Common Stock                               900             900             530
      06/20/97        Common Stock                             1,001           1,001             532
      06/25/97        Common Stock                             5,334           5,334           2,762
      07/10/97        Common Stock                            17,967          17,967           8,565
      09/16/97        Common Stock                             3,533           3,533           1,026
      09/26/97        Common Stock                            28,666          28,666           7,540
      10/03/97        Common Stock                               200             200              49
      10/15/97        Common Stock                             8,239           8,239           1,738
      10/16/97        Common Stock                             2,250           2,250             468
      12/10/97        Common Stock                               556             556              32
      12/18/97        Common Stock                               719             719              26
      12/22/97        Common Stock                             2,000           2,000              49
      12/26/97        Common Stock                             2,000           2,000              27
      01/08/98        Common Stock                            40,137          39,257
      01/12/98        Common Stock                             5,400           5,222
      01/16/98        Common Stock                             3,342           3,196
      01/26/98        Common Stock                             1,500           1,393
      01/28/98        Common Stock                            19,333          17,850
      01/29/98        Common Stock                               300             276
      02/03/98        Common Stock                             8,000           7,255
      02/06/98        Common Stock                             1,000             899
      02/09/98        Common Stock                             7,333           6,529
      02/10/98        Common Stock                             1,200           1,065
</TABLE>
<PAGE>   2
<TABLE>
<CAPTION>
                                                                                  Weighted Average Number of Shares
                                                         ---------------------------------------------------------------------------
        Date           Description                          Total        Year Ended       Year Ended      Year Ended     Year Ended
       Issued          of Issuance                       Outstanding      31-Dec-98       31-Dec-97       31-Dec-96      31-Dec-95
------------------------------------------------------------------------------------------------------------------------------------
<S>                   <C>                              <C>             <C>             <C>             <C>             <C>
      02/11/98        Common Stock                             3,256           2,881
      02/17/98        Common Stock                             8,200           7,122
      02/25/98        Common Stock                             2,800           2,370
      03/04/98        Common Stock                               200             165
      03/06/98        Common Stock                             3,800           3,123
      03/11/98        Common Stock                             9,300           7,516
      03/12/98        Common Stock                             1,400           1,128
      03/13/98        Common Stock                             2,600           2,087
      03/23/98        Common Stock                             7,067           5,480
      04/02/98        Common Stock                             3,000           2,244
      04/06/98        Common Stock                             3,800           2,800
      04/07/98        Common Stock                             6,667           4,895
      04/13/98        Common Stock                             1,700           1,220
      04/20/98        Common Stock                             3,700           2,585
      04/24/98        Common Stock                         6,957,519       4,784,486
      04/27/98        Common Stock                             1,000             679
      05/07/98        Common Stock                         1,951,000       1,272,159
      05/12/98        Common Stock                               800             511
      05/18/98        Common Stock                             2,000           1,244
      05/19/98        Common Stock                             4,400           2,724
      05/21/98        Common Stock                             2,700           1,657
      05/26/98        Common Stock                            24,167          14,500
      05/27/98        Common Stock                             3,600           2,150
      06/05/98        Common Stock                             2,000           1,145
      06/08/98        Common Stock                               975             550
      06/10/98        Common Stock                             3,200           1,788
      06/25/98        Common Stock                            10,000           5,178
      06/29/98        Common Stock                               400             203
      07/02/98        Common Stock                            12,583           6,275
      07/06/98        Common Stock                             1,600             780
      07/14/98        Common Stock                             4,700           2,189
      07/16/98        Common Stock                               200              92
      07/22/98        Common Stock                               800             355
      07/23/98        Common Stock                             1,100             485
      07/29/98        Common Stock                            26,800          11,382
      08/03/98        Common Stock                            30,667          12,603
      08/12/98        Common Stock                             6,500           2,511
      08/20/98        Common Stock                             2,200             802
      08/26/98        Common Stock                            17,067           5,938
      09/17/98        Common Stock                             7,500           2,158
      10/02/98        Common Stock                               400              99
      10/05/98        Common Stock                            11,106           2,647
      10/07/98        Common Stock                               260              61
      10/19/98        Common Stock                             2,833             567
      10/21/98        Common Stock                             4,492             874
      10/27/98        Common Stock                         8,654,156       1,541,151
      10/30/98        Common Stock                                35               6
      11/09/98        Common Stock                               100              14
      11/16/98        Common Stock                            12,950           1,597
      11/17/98        Common Stock                        10,096,451       1,217,106
      11/19/98        Common Stock                            12,760           1,468
      11/24/98        Common Stock                             6,000             608
      11/25/98        Common Stock                                77               8
      11/30/98        Common Stock                            14,000           1,189
      12/02/98        Common Stock                               411              33
      12/07/98        Common Stock                             8,110             533
      12/08/98        Common Stock                            12,033             758
      12/11/98        Common Stock                             2,000             110
      12/15/98        Common Stock                               250              11
      12/22/98        Common Stock                                37               1
      12/23/98        Common Stock                                95               2
      12/24/98        Common Stock                                80               2
      12/29/98        Common Stock                            10,000              55
      12/30/98        Common Stock                             1,537               4
</TABLE>
<PAGE>   3
<TABLE>
<CAPTION>
                                                                                  Weighted Average Number of Shares
                                                         ---------------------------------------------------------------------------
        Date           Description                          Total        Year Ended       Year Ended      Year Ended     Year Ended
       Issued          of Issuance                       Outstanding      31-Dec-98       31-Dec-97       31-Dec-96      31-Dec-95
------------------------------------------------------------------------------------------------------------------------------------
<S>                   <C>                              <C>             <C>             <C>             <C>             <C>
      12/31/98        Common Stock                             8,584               0
                                                          ----------   -------------   -------------   -------------   ------------
                      Total                               60,249,301      41,202,037      32,116,957      31,041,206     30,189,763
                                                          ==========   =============   =============   =============   ============

                      Loss before
                        extraordinary item                             ($503,927,000)  ($328,557,000)  ($254,454,000)  ($90,785,000)
                      Preferred stock dividend                           (18,761,000)    (11,978,000)              0              0
                                                                       -------------   -------------   -------------   ------------
                                                                        (522,688,000)   (340,535,000)   (254,454,000)   (90,785,000)

                      Loss from early
                        extinguishment of debt                           (30,689,000)     (4,500,000)              0              0

                                                                       -------------   -------------   -------------   ------------
                      Loss available to
                        common shareholders                            ($553,377,000)  ($345,035,000)  ($254,454,000)  ($90,785,000)
                                                                       =============   =============   =============   ============

                      Basic and diluted net
                        (loss) per common share:
                      (Loss) before extraordinary item                       ($12.69)        ($10.60)         ($8.20)        ($3.01)
                      Extraordinary item                                       (0.74)          (0.14)           0.00           0.00

                                                                       =============   =============   =============   ============
                      Net (loss) per common share                            ($13.43)        ($10.74)         ($8.20)        ($3.01)
                                                                       =============   =============   =============   ============
</TABLE>