301 redirect

301 vs 302 — the key distinction

	301 (permanent)	302 (temporary)
Intent	The new URL is the URL going forward	The original URL will return; this is a temporary detour
Browser caching	Cached aggressively	Not cached; checked again on next visit
SEO signal passing	Passes most of the ranking signal	Historically passed less, now treated similarly to 301 in many cases — but intent still matters
Use case	Migrations, URL restructures, consolidations	A/B tests, geographic routing, temporary maintenance redirects

For permanent URL changes, use 301. Using 302 for a permanent move sends the wrong signal to crawlers and may delay full canonical migration.

How 301 passes ranking signals

When Google encounters a 301:

1. The old URL drops out of the index over time
2. The new URL inherits the ranking position
3. Inbound link equity from old URL → new URL (with ~10-15% signal loss per hop, modern estimates)
4. Internal links to the old URL still resolve via the redirect, but should be updated to point directly to the new URL for optimal signal

Redirect signal loss math

Each 301 hop reduces signal slightly. A redirect chain of 3 hops:

Old URL → URL_B → URL_C → Final URL

Each arrow is ~85% signal pass-through. Total signal arriving at Final URL: 0.85³ ≈ 61% of original.

Avoid chains. Point all redirects directly to the final destination URL.

When 301s break things

Common 301 pitfalls:

• Pointing the entire old site to homepage — loses all topical relevance; old content’s ranking on topic-specific queries vanishes
• Redirect chains over 5 hops — Googlebot stops following them
• 301 to a 404 — broken redirect chain leaks all signal
• Mixed 301/302 in the same chain — confuses Google’s canonical resolution
• 301 between protocols/subdomains without consistency — http→https→non-www→www patterns can produce 4-hop chains by accident

Best practice for SEO migrations

• 1:1 URL mapping — every old URL maps to the most relevant new URL (not the homepage)
• Direct, not chained — final destination in one hop
• Pre-migration redirect map — documented before launch
• Post-migration audit — Search Console crawl errors monitored for 30+ days
• Internal links updated — pages within the site link to NEW URLs, not redirected old URLs

See our SEO Migration service for the full migration playbook.

Resocial perspective

We treat 301 hygiene as a foundational technical SEO check. Sites with sloppy redirect histories (especially post-acquisition mergers) accumulate chains that leak ranking signal silently. Our nightly audit flags any chain over 2 hops; we collapse them to direct redirects in the next sprint.