The formula of ROI:

R = (P / E)*100%, where

P – useful end results in monetary terms.

E – the cost of achieving this result in terms of money.
It should be noted here that. In relation to the business or activities of private entrepreneurs , profitability is calculated for a certain period of time – usually a month, quarter or year. In this case, the final outcomes and costs over a selected time interval exactly match the balance sheet figures for the corresponding period (income and consumption respectively). The same is true regarding groups of companies and even industries – however, there will often have to resort to statistical estimates and errors.
Take for example a small Agency that sells tickets for concerts and performances. It is necessary to calculate its quarterly profitability.
The Agency acts as an intermediary and has no need to print your tickets. Work: Director, accountant, 12 staff and 70 freelance distributors of tickets, and 4 drivers with own transport. From time to time, the Agency enlists the aid of a legal Agency.

The Agency has a sales office.
Let the total Agency expenses for the quarter are:

Payroll 1.35 million RUB;

Charges, taxes, payment of 1.2 million rubles

Rent, bills and entertainment expenses – of 1.74 million rubles.

Total: 1,35 + 1,2 + 1,74 = 4.29 million RUB
Even for a quarter of the tickets sold for 34 concerts with a total sum of 154 million rubles., of which the intermediary Agency has a percentage of 12%.

For the quarter was also received income securities 0,54 mln. RUB.

Other income in cash, the company came to 1.4 million.

Total: (154*12% = 18,48) + 0,54 + 1,4 = 20,42 million.
The profitability of the Agency during the quarter is:

R = 20,42 / 4,29 = 4,76, or 476%.