[(Basic + DA)/26x8]x2xtotal Overtime Hours.
Below is a brief on overtime for your understanding as per the act.
As per Factories Act:
Overtime: Where a worker works in a factory for more than nine hours in any day or for more than forty-eight hours in any week, he shall, in respect of overtime work, be entitled to wages at the rate of twice his ordinary rate of wages.
For the purposes of sub-section (1), "ordinary rate of wages" means the basic wages plus such allowances, including the cash equivalent of the advantage accruing through the concessional sale to workers of foodgrains and other articles, as the worker is for the time being entitled to, but does not include a bonus and wages for overtime work.
As per Minimum Wages Act:
(1) When a worker works in an employment for more than nine hours on any day or for more than forty-eight hours in any week, he shall in respect of overtime work, be entitled to wages -
(a) in the case of employment in agriculture, at one and a half times the ordinary rate of wages;
(b) in the case of any other scheduled employment, at double the ordinary rate of wages;
Shops & Establishment Act:
Overtime: For any work in excess of nine hours on any day or for more than 48 hours in any week, overtime wages are to be paid at the rate of double the wages. It is provided therein that where a worker is required to work beyond the normal hours of work or on any day of rest, he shall be entitled to wages at the rate of twice his ordinary rate of wages in respect of the overtime work or work done on a day of rest, as the case may be.
When payment is made on a monthly scale of pay, the daily rate of wages for a worker can be obtained only by dividing the amount of wages for 30 days by 26. This is done because the workman is entitled to four days as weekly rest during which period he does not work. The reason is that the workman actually gets monthly wages for the work done only for 26 days. Thus for a workman, it is the actual receipt for 26 days which is his monthly scale of pay, i.e., 30 days wages. Therefore, a day's wage should mean the result obtained by dividing the monthly wages by the actual number of working days, i.e., 26 days. This principle will, however, be applicable in the case of such workers who get monthly wages only for the actual number of working days. The formula for the calculation of the overtime wages for one hour is to divide the month's wages by 26 into the number of normal working hours and the result so obtained by them then multiplied by two to calculate one hour's overtime wages.
Hope you have got a fair idea on Overtime and calculation.