In the home meal replacement industry, forecasting the number of customers is important. If it is possible to forecast the number of customers, it will be possible to reduce the loss of food waste. In this study, we attempted to estimate the number of customers from the date data such as the day of the week by using the T-method in quality engineering. We found a strong correlation between the actual and the estimated number of the customers, with a match rate of 82%. Moreover, the feature items of the date data effective for the number of customer estimation were revealed.