
Ask HN: How to calculate future usage with reasonable buffer - bryanrasmussen
I have to calculate out future usage of a paid for API that we have to buy credits for usage. I wonder if there is any book or hopefully shorter than a book guideline on doing this kind of task - so that I can say I followed procedure X which means that based on our past usage of 100,000 requests per month we should purchase these credits for the next year which gives us a 25% extra buffer per month.
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brudgers
Use a spreadsheet to create a forecast model. Create best case, worst case and
medium case volume scenarios. Assign probabilities to each. Plug in some cost
numbers. Generate the cross products discounting costs with probabilities and
the time value of money. Look at the numbers.

Roughly, this is financial accounting and part of what running a business
usually means. It should form the basis for cash flow analysis.

Now my general advice: don't spend money until you have to. YAGNI is more
common than people imagine because things are almost invariably either worse
or better than imagined.

Good luck.

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bryanrasmussen
I don't want to say I expect it to work exactly the same as the past, and I
don't have a buffer of credits to use if usage increases. So I would like to
buy some extra credits to handle unexpected increases, and was hoping there
was some research on how you should make the determination of how much extra
capacity to plan for 'just in case'

damn, saying it just makes it seem very unlikely to exist and I will have to
just recommend let's buy 20% extra just in case.

edited: for clarity and brevity.

