Never forecasted in Excel before, is this defensible/am i doing it right?

[loct99]

2009 10,865
2010 11,550
2011 11,777
2012 11,744
2013 11,876


Those are my two columns.... Year and Sales.

Using forecast or Slope it pretty much gives me a slope of 221. so I just add that slope or use forecast which adds that slope for me and that will give me my value for my next year. And i keep repeating.

Is this ok for a rudimentary forecast? I also have the USA total sales for this product for the past 5 years which has grown at a much faster rate, which I guess i could argue this market could simply be lagging behind sales and the 221 slope should be higher, but i dont know how to compute that

[mcmahobt]

For a rudimentary forecast, this should be alright since your data is linear. Just note that using the standard form of y=221x+b vs the FORECAST function will give you a delta of ~0.2 if you keep your forecast range static within your source data range.