Does a Proxy Save Your Internet Data?
Follow a proxied download across both network legs and explain when caching or compression can reduce transfer volume.
A 100 MB file still has to reach your device. The website sends it to the proxy, then the proxy sends it to you. Changing the exit IP does not remove that second leg from your own internet connection.
Caching can save a different link. A shared cache on the local network may avoid repeated fetches across the office uplink. A remote cache reached across your metered connection still sends the response over that connection.
Nor can the proxy store every response indiscriminately. Requests and responses must meet HTTP caching rules, including the restrictions relevant to private data.
An ordinary HTTPS CONNECT relay carries encrypted content. You cannot assume it sees and recompresses the webpage. Existing compression, already-compressed media and protocol overhead affect any savings too.
Ask what the advertised number measures: bytes fetched by the proxy, bytes crossing an office link, or bytes arriving at a phone? Keep the workload, measured link and cache-hit conditions with the comparison. For an IP-changing proxy, budget normal download volume plus overhead unless a separate data-reduction feature has evidence for your actual path.