Exhibit 12 Statement of computation of ratios. 196 Statements re: Computation of Ratios Item 1(l) Business - Statistical Disclosure VI. Return on Equity and Assets Brenton Banks, Inc. (Dollars in thousands) December 31, 1998 1997 1996 Return on average total assets: Net income (before deduction of minority interest) $ 21,071 18,753 14,618 * divided by * Average assets $ 1,780,120 1,649,469 1,582,894 Ratio 1.18% 1.14% 0.92% Return on average common stockholders' equity: Net income $ 20,351 18,010 14,015 * divided by * Average common stockholders' equity $ 132,422 124,491 119,170 Ratio 15.37% 14.47% 11.76% Common dividend payout ratio: Cash dividends per share $ 0.349 0.248 0.188 * divided by * Net income per share - diluted $ 1.05 0.91 0.69 Ratio 33.24% 27.25% 27.25% Average equity to average assets: Average equity $ 132,422 124,491 119,170 * divided by * Average assets $ 1,780,120 1,649,469 1,582,894 Ratio 7.44% 7.55% 7.53% Equity to assets ratio: Common stockholders' equity excluding unrealized gains (losses) on assets available for sale $ 131,892 126,159 120,877 * divided by * Total assets excluding unrealized gains (losses) on assets available for sale $ 1,936,238 1,715,264 1,631,018 Ratio 6.81% 7.36% 7.41% 197 December 31, 1998 1997 1996 Tier 1 leverage capital ratio: Common stockholders' equity excluding unrealized gains (losses) on assets available for sale $ 131,891 126,159 120,877 Minority interest 4,931 4,859 4,615 Less: intangibles (1,970) (2,087) (2,704) Less: minimum MSR's to be deducted (388) --- (115) Tier 1 capital $ 134,446 128,931 122,673 * divided by * Quarterly average total assets excluding unrealized gains (losses) on assets available for sale 1,878,074 1,692,176 1,613,223 Less: intangibles (1,970) (2,087) (2,704) Less: minimum MRS's to be deducted (388) --- (115) Tier 1 assets $ 1,875,716 1,690,089 1,610,404 Ratio 7.17% 7.63% 7.62% Primary capital to assets: Common stockholders' equity excluding unrealized gains (losses) on assets available for sale $ 131,892 126,159 120,877 Minority interest 4,913 4,859 4,615 Allowance for loan losses 14,172 12,732 11,328 Primary capital $ 150,977 143,750 136,820 * divided by * Total assets excluding unrealized gains (losses) on assets available for sale $ 1,936,238 1,715,264 1,631,018 Allowance for loan losses 14,172 12,732 11,328 Allowable assets $ 1,950,410 1,727,996 1,642,346 Ratio 7.74% 8.32% 8.33% 198 December 31, 1998 1997 1996 Net Noninterest Margin: Noninterest income $ 33,358 27,506 23,327 Less: Securities gains (losses) 665 494 321 Less: Noninterest expense 61,392 57,699 56,091 Net noninterest income $ (28,699) (30,687) (33,085) * divided by * Year-to-date average assets $ 1,780,120 1,649,469 1,582,894 Ratio -1.61% -1.86% -2.09% Efficiency Ratio: Noninterest expense $ 61,392 57,699 56,091 * divided by * Noninterest income 33,358 27,506 23,327 Less: Securities gains (losses) 665 494 321 Less: Loan gains (losses) 81 78 84 T.E. net interest income 65,279 63,701 59,238 Subtotal 97,891 90,635 82,160 Ratio 62.71% 63.66% 68.27% 199