Relevance. According to Rosstat, for 2021 share of small agribusiness in the gross harvest of potatoes was 77.8%, vegetables — 71.6%, in production of raw milk — 43.8%, livestock and poultry (in live weight) — 21.9%. However, according to the 2021 census, compared to 2016, the number of small businesses in Russia decreased by an average of 25%. The number of agricultural organizations that are not small businesses increased by 26.3% over the specified period. In order to support small agribusiness, the authors have developed an economic model for calculating the profitability of business concepts for these categories of farms, aimed at automating the assessment of the effectiveness of doing business and investment.Methods. To build the concept of calculations, methods of comparative, statistical analysis, economic and mathematical approach were used. To implement the methodology for calculating the profitability, the basic algorithms of financial mathematics and the functions of the financial category built into the spreadsheet processor MS Excel were used.Results. The model allows to evaluate the cost of investments, credit funds; plan the number of staff; recalculate financial results taking into account the use of loans and subsidies; calculate taxes. In order to test the model, an assessment was made of the effectiveness of investing in dairy cattle breeding in the Chuvash Republic. The model was run 88 times to calculate the payback period for investments in the construction and launch of a dairy farm with a population of 250 head in the main herd with different productivity of cows and applied state support. According to the results of calculations, with an average and high productivity of cows (6500–9000 kg), taking into account the use of the main areas of subsidizing the industry available in the republic, the return on investment can come in 4 years.