Compounding Calculator taking into account regular monthly contributions as well as single annual lump sum ?

Hi,
As the title says does anyone know of a calculator that would allow to calculate a monthly contribution but also allow for a single large contribution every year

ie my monthly contribution & a portion of bonus, call it 10K that's put into the pension 01 Jan each year in addition

Thanks

Might be simpler to knock something up in Excel?

Not exactly what you're looking for
What if you calculate the monthly value of a annual contribution? Eg annual contribution 12k in January equals approx 1033 per month for 12 months. Giving approx 12,740 after 12 months at 6%