Difference between Zerodha margin and total margin


In Zerodha margin page, I find 2 tabs, one is for SPAN margin which contains the total margin required by the exchange and the next tab contains Equity futures. Please let me know in case of taking positional futures (overnight position) which margin needs to be followed.

For example,

For Century Textiles, it shows Total margin required Rs. 69,980.00 (under SPAN margin i.e. SPAN 43,280 + Exposure 26,625 ) and Rs 70,140.00 (in Equity futures tab)

You should use the SPAN calculator to know exact Margin required. Span calculator is live, which means it takes the current market price of CENTURYTEX futures which is close to 533 now and calculates the margin.
Yesterday closing price of CENTURYTEX is 537.2 upon which the calculation will yield 70,140 as margin (this is what you are seeing in Eq Futures tab).
You can also use the equity futures tab to calculate the number of contracts you can buy, since you will explicitly mention the CMP of 533 as entry price. The calculator will automatically consider the SPAN calculator value 69980 as base and will tell you how many contracts you can buy.
There is a pdf link on top of the Equity Futures tab, if you open it you can see the IL&FS calculated sheet of futures which is based on yesterdays closing price. Have a look at it!
In summary you can use both SPAN Margin Calc and Equity Futures Calc.
Both will give correct results.
Actual Margin will be the Span Margin Calc value.