Hi,

I am not quite sure which formula you are referring to, but as a general response, I have created a quick example (attached) which assumes you have created a weekly model, which is then summarised using MOD, SUMIF and LOOKUP.

Liam

Thank you

You're welcome.  The trick is always to model at a base, consistent periodic level (here weeks) and then consolidate how you like.  It's a similar idea if you wanted a model that was monthly for the first year, quarterly for the next two and then annual thereafter - you'd just model monthly through and then consolidate accordingly.