EXHIBIT 12.1 PENTACON, INC. AND SUBSIDIARIES RATIO OF EARNINGS TO FIXED CHARGES (In Thousands of Dollars) HISTORICAL PRO FORMA ------------------------------------------------------------------------------- ------------- FISCAL NINE MONTHS FISCAL THREE MONTHS YEAR ENDED YEAR ENDED DECEMBER 31, ENDED YEAR ENDED DECEMBER 31, ENDED --------------------------- SEPTEMBER 30, SEPTEMBER 30, ----------------- SEPTEMBER 30, 1994 1995 1996 1997 1998 1997 1998 1998 ------- ------- ------- ------------- ------------- ------- ------- ------------- CONSOLIDATED: Earnings: Income before income taxes ..................... $ 837 $ 2,419 $ 4,139 $ 4,529 $ 10,060 $ 248 $ 3,176 Fixed charges ................ 843 1,409 1,313 1,175 2,967 348 3,202 ------- ------- ------- ------------- ------------- ------- ------- $ 1,680 $ 3,828 $ 5,452 $ 5,704 $ 13,027 $ 596 $ 6,378 ======= ======= ======= ============= ============= ======= ======= Fixed Charges: Interest expense ............. $ 686 $ 1,235 $ 1,118 $ 1,015 $ 2,448 $ 295 $ 2,953 Portion of rental cost representing interest ..... 157 174 195 160 444 53 175 Net amortization of debt issuance costs ....... -- -- -- -- 75 -- 74 ------- ------- ------- ------------- ------------- ------- ------- $ 843 $ 1,409 $ 1,313 $ 1,175 $ 2,967 $ 348 $ 3,202 ======= ======= ======= ============= ============= ======= ======= Ratio of earnings to fixed charges ................. 2.0x 2.7x 4.2x 4.9x 4.4x 1.7x 2.0x ======= ======= ======= ============= ============= ======= ======= PRO FORMA: Earnings: Income before income taxes ..................... $ 8,666 $ 1,264 Fixed charges ................ 4,361 5,114 ------------- ------- $ 13,027 $ 6,378 ============= ======= Fixed Charges: Interest expense ............. $ 3,652 $ 4,777 Portion of rental cost representing interest . 444 175 Net amortization of debt issuance costs ....... 265 162 ------------- ------- $ 4,361 $ 5,114 ============= ======= Ratio of earnings to fixed charges ................. 3.0x 1.2x ============= ======= PRO FORMA AS ADJUSTED: Earnings: Income before income taxes ..................... $ 15,715 Fixed charges ................ 17,165 ------------- $ 32,880 ============= Fixed Charges: Interest expense ............. $ 15,950 Portion of rental cost representing interest 707 Net amortization of debt issuance costs ....... 508 ------------- $ 17,165 ============= Ratio of earnings to fixed charges ................. 1.9x =============