project figures for rest of this year based on last 18 months?

I have monthly sales figures for 2015 and the first 6 months of 2016. I want to estimate sales figures for the rest of 2016.

The annual sales figures have significant seasonal peaks and troughs and as this is a new business, sales are increasing exponentially all the time.

The seasonal peaks and troughs mean i can't fit any kind of linear or non-linear progression to put into an excel function.

I'm trying to work out a way of repeating the peaks and troughs i.e. the shape of the graph but also apply the exponential increase to the remaing 6 months.

Any help would be gratefully received!

Without at least some sample data it would be difficult to provide a tailor made solution for this. However, have a look at the link below. The last chart shows that I think you're hinting at, so could possibly help.
https://www.searchlaboratory.com/201...n-using-excel/

BSB

That's exactly what I want... now i just have to understand it!

I thought the answer might be to find a seasonal variation and a seperate growth rate but couldn't work out how - thanks!

Doesn't look too daunting.

If you get stuck, post some desensitized sample data and we can go from there.

BSB

EDIT: I typed everything below, then renewed the thread and saw that quite a bit of my input had been covered. I'm posting anyway, because I typed it all and I'm stubborn. BSB is right, though, some data to look at would help.

It might be tricky to get something clean, but I would investigate breaking the data into pieces to examine two separate approaches:

1) See if you can find a correlation between early 2016 and early 2015. Is the relationship between March 2016 and March 2015 similar to the relationship between Feb 2016 and Feb 2015? i.e. is the annual growth factor steady(ish)?

2) See if month-to-month percentage predictions play out with any accuracy, to account for the seasonality. e.g. March 2015 was 16% greater than Feb 2015, so March 2016 should be 16% greater than February 2016.

Ultimately, if your new business growth is significant, you'll need a combination of the two factors. Compare each month to the same month of the previous year so that you can come up with a baseline representation of the business growth, then factor in the month-to-month percentage modulations to account for the seasonality. This is the approach I use in my line of work, but I benefit from having a pretty stagnant growth factor (we're not new). It's hard to say for certain without data, but hopefully the numbers make it possible to explore. Good luck!