The short answer: An HTTP 301 means "This page has moved permanently; delete the old URL from your index and give all ranking power to the new one." An HTTP 302 means "This is temporary; keep the old URL indexed and do not transfer search authority." Using the wrong one during a migration will silently freeze your organic traffic.
The Core Difference: Permanent vs. Temporary
Search engines treat URLs as unique legal entities. When you change a URL path, domain name, or protocol, you must communicate whether the change is permanent:
| Status Code | Browser Cache | Search Engine Index | Link Equity (PageRank) |
|---|---|---|---|
| 301 Moved Permanently | Cached indefinitely | Replaces old URL with new destination | Transfers 90% – 99% of authority |
| 302 Found (Temporary) | Not cached (checked every visit) | Keeps old URL indexed in search results | Does not transfer permanent authority |
Does a 302 Pass Google PageRank?
Historically, 302 redirects passed zero PageRank. While Google's modern crawl algorithms try to guess your intent if a 302 stays live for several months (eventually treating it as a canonical signal), relying on this is a huge gamble.
Bing, Yandex, and other search engines strictly adhere to the HTTP specification: if they see a 302, they will continue ranking the original URL and attribute external backlinks to the old, redirected address.
When Should You Actually Use a 302 Redirect?
Never use 302 for site migrations, domain rebranding, or permanent URL slug updates. However, 302s are ideal for:
- A/B Testing & Split Experiments: Sending 50% of visitors to a temporary landing page variation without indexing it over the original.
- Geo-Targeted Routing: Forwarding visitors based on their IP country (e.g. redirecting UK visitors to
/en-gb/) while keeping the global URL intact. - Temporary Maintenance: Redirecting customers to a temporary holding page while server upgrades complete.
- Out-of-Stock Product Rotation: Temporarily redirecting seasonal shoppers to a related category page while inventory restocks.
How Long Does Google Take to Transfer Authority After a 301?
Google does not update its index instantaneously. After implementing a 301 redirect:
- Googlebot must re-crawl the original URL to detect the 301 response header.
- Googlebot schedules a crawl for the new destination URL.
- The internal link graph recalculates canonical signals (typically takes 3 to 14 days for active sites, or up to 6 weeks for low-frequency sites).