Azure Storage Growth Calculator

capacity = current × (1 + monthly growth)^months; doubling time = ln2 ÷ ln(1 + growth); data younger than the lifecycle window is the share added in the last months, so hot share = 1 − 1 ÷ (1 + growth)^window. Storage grows compound, not linear, so 6% a month is a doubling roughly every twelve months. With a lifecycle rule the hot tier only ever holds the data written inside the rule's window, and because growth is exponential that share stays small — which is exactly why tiering keeps the blended price near the cool rate as the dataset expands.

Capacity forecasts made by adding last month's growth understate the year-end number badly, and knowing the doubling time tells you when quota, redundancy and lifecycle decisions have to be revisited; confirm per-GiB tier prices for your region and redundancy setting in the Azure pricing calculator.

This calculator takes 6 inputs: Current capacity, Monthly growth rate, Planning horizon, Move data to cool after, Hot price per GiB, Cool price per GiB. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.