ESP8266 Community Forum

Let me sum it up in short question.

Let say I have program that uses 60% of 1044464 bytes Program Space.

with NO SPIFF and other minimum resource, will 4MB chip can do the OTA easily. Although by term OTA:~1019KB it implies it can do, excluding other if else scenarios.

Yes. If it fits you can get easily yourself using built-in functions like ESP.getFreeSketchSpace() (also documented here https://arduino-esp8266.readthedocs.io/ ... cific-apis )