In the present research, the potential of a nondestructive method for predicting tomato skin rupture force and skin firmness using color values taken by handheld colorimeter was explored. Bandita F1 variety greenhouse tomatoes were used in the test. L, a and b color values of 238 tomatoes harvested at six different maturity stages were measured by Minolta CR-400 model colorimeter. Skin rupture force and skin firmness of tomatoes were measured as firmness parameters and correlated with color values. Tomato firmness parameters and L, a and b values were fitted in different forms of models using multiple linear regression (MLR). The model using MLR on variables a, b and the product ab was selected. Average firmness values of 238 tomato samples were primarily separated to two groups. 70% and 30% of color and firmness values were used for calibration and validation data set, respectively. Calibration and validation of chosen model equation were tested by using tomato samples of 167 and 71 data set, respectively. Relationship between measured and predicted tomato skin rupture force in the case of using a, b and ab color values was found high. Furthermore, coefficient of determinations for calibration and validation data set were found to be 0.88 and 0.89, respectively. This performance shows that nondestructive color measurement by handheld colorimeter could be used for real-time firmness prediction of tomatoes.