1 sec interrupt from 16MHz internal clock

[shantanu@india]

I have a 18F24K22 where I need a 1 sec TMR0 interrupt routine. I set the prescaler to 1/256 and the clock to instruction cycle. If I preload TMR0H and TMR0L with 49910 then the timer generates interrupt after (65535-49910)*(1/4)*(256)=1000000 microsec =1 second.
Are my calculations OK?

[trastikata]

Excluding writes to TMR0, I get 1.000064s with a 49910, and 1s with 49911. Writes to TMR0 are two cycles if I am not mistaken, thus 49909 for 1s interrupt.

[shantanu@india]

As usual, spot on Trastikata