Inventory Forecasting

Last updated May 2023

Feel free to use our simple inventory forecaster, which tells you the most likely amount of impressions or page views you will receive next month, and what likely scenarios look like. (It also works with revenue).

If your results are increasing, expect them to keep going up. If they are decreasing, expect them to keep going down.



Inventory Forecasting For Publishers

As a website owner, you will, of course, be very interested in inventory forecasting. That is estimating future levels of adverts available to sell so you can work out much money you will be able to make from your site via online advertising.

This process is unfortunately not an exact science, as you are attempting to predict the future.

The simplest and most effective way to get a good estimate is to simply use the number of impressions etc you received from the month before. This amount will increase or decrease slightly (probably no more than 25%), but in terms of getting your estimated figure as accurate as possible, it’s your best bet.


Better Forecasting

If you want better inventory forecasts, you will need to keep track of all your relevant data. This includes things like:

  • ad impressions
  • marketing spend
  • channel growth
  • page count growth
  • seasonal user count changes.

If you track this over a long period you could potentially try to work out a formula that works for you.

We would generally not recommend doing this, however. The benefit you receive will likely be outweighed by the time it takes. This is because this is a huge ongoing project, but inventory levels change only a little (and inconsistently) over time.

If you want to know what next month is going to look like, check out recent trends and apply them to last month. It’s very likely that you’ll not be far off. Or at least no further off than a complicated time-consuming model.

Many people and companies have tried many complicated and convoluted ways to make their inventory forecasting more accurate. None have succeeded in any major way. Unless you have a magic link to the future, we recommend you don’t get sucked into trying to outdo them either.


Top Tip: If you want to try to do this in Excel, we recommend the forecast.ets function.

It’s a bit complicated and no more accurate than the above, but still useful.


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