HTTP status codes are the language servers speak to browsers and crawlers. Every response carries a message. Using the wrong code does not just confuse Googlebot. It actively damages your SEO.
Think of status codes like postal return messages. A 200 says “delivered successfully.” A 301 says “forwarding address, please update your records.” A 302 says “temporarily away, try again later.” A 404 says “no such address.” A 410 says “address cancelled, stop trying.”
Send the wrong message and the recipient acts on wrong information. A 302 where you meant 301 can keep old URLs competing with new ones for months. A soft 404 returning 200 wastes crawl budget on pages that should have been removed from the index.
This guide covers the status codes that directly impact SEO, when to use each one, and the mistakes that cost sites rankings.
The Codes That Matter
Eight status codes cover 99% of SEO-relevant situations: 200, 301, 302, 304, 404, 410, 500, and 503.
The 2xx range indicates success. Page content gets indexed normally.
The 3xx range indicates redirection. This is where link equity transfer and URL consolidation happen.
The 4xx range indicates client errors. These trigger page removal from the index.
The 5xx range indicates server errors. Temporary issues cause crawl problems. Prolonged errors hurt rankings.
301: Permanent Redirect
A 301 tells search engines this URL has permanently moved to a new location. The signal is definitive. Update your index, transfer ranking signals, stop returning the old URL in search results.
When to use 301: URL structure changes, domain migrations, HTTP to HTTPS transitions, consolidating duplicate content like www versus non-www or trailing slash variations, merging pages with similar content, and local business rebranding.
Consider a Nashville, TN plumber who has built years of local SEO equity under nashvilleplumber.com. When rebranding to acmeplumbingnashville.com, a 301 redirect preserves that accumulated authority. Without it, the new domain starts from zero while the old domain’s equity slowly decays. The 301 is not just a technical nicety. It is protecting years of marketing investment.
Link equity transfer through 301 redirects passes nearly all ranking power to the destination URL. The “nearly all” qualifier exists because some minimal loss occurs, but for practical purposes, a 301 preserves ranking power effectively.
Implementation permanence matters. Once implemented, leave 301 redirects in place. Google’s John Mueller has stated redirects should remain for at least one year, preferably indefinitely. Removing a 301 before Google has fully consolidated the URLs can resurrect the old URL in the index.
302: Temporary Redirect
A 302 indicates a temporary move. The old URL should remain in the index because the content will return there eventually.
When to use 302: A/B testing where the original URL will be restored, temporary content moves during site maintenance, geolocation redirects where users redirect based on location but the original URL is still valid, and promotional redirects that will expire.
The 302 confusion persisted for years. SEO guidance stated that 302s do not pass link equity. Google updated this behavior. 302s now pass ranking signals similarly to 301s in most cases. However, Google may continue indexing the original URL longer with a 302 than with a 301.
When 302 becomes problematic: long-term 302s send mixed signals. If a redirect has been in place for months with no intention of reverting, it should be a 301. Google might eventually treat persistent 302s as 301s, but you are relying on Google’s interpretation rather than stating your intent clearly.
The decision framework is simple. Will the old URL come back? Use 302. Is this permanent? Use 301. Unsure? Default to 301. It is almost always the right choice.
307 and 308: The HTTP/1.1 Versions
307 (Temporary) and 308 (Permanent) preserve the HTTP method during redirect. They exist because 301 and 302 historically allowed browsers to change POST requests to GET requests during redirect.
For SEO purposes, 307 functions like 302 and 308 functions like 301. Most sites do not need these codes unless dealing with form submissions or API endpoints that must preserve POST data through redirects.
404: Not Found
A 404 tells browsers and crawlers the requested resource does not exist. It is the appropriate response when a page has been removed and there is no equivalent replacement.
When to use 404: page deleted with no logical successor, URL never existed in the first place like typos or bot probes, and content that should not be accessible anymore.
Google removes 404 pages from the index, but not immediately. Google recrawls the URL to confirm the 404 persists before removing it. This can take days to weeks depending on the page’s crawl frequency.
Do not redirect everything. The instinct to 301 every deleted page to the homepage is wrong. Mass redirects to irrelevant destinations look manipulative and provide poor user experience. A user looking for a discontinued product does not want the homepage. They want to know the product is unavailable.
Custom 404 pages help users when they land on dead URLs from old links. Include navigation, search functionality, and links to popular content. A helpful 404 page reduces bounce rate and can guide users to what they actually need.
410: Gone
A 410 tells search engines the resource is permanently gone. Unlike 404 which says “not found,” 410 explicitly communicates “this existed but has been intentionally removed and will not return.”
When to use 410: content permanently and intentionally removed, pages you want removed from the index faster, and legal or compliance removals like GDPR requests.
Google’s Gary Illyes has stated that 410 might result in slightly faster removal from the index than 404, but the difference is marginal. In practice, both work correctly when implemented.
Practical recommendation: use 404 by default. Reserve 410 for situations where you specifically want to signal permanence, such as content removed for legal reasons or compliance requirements.
Soft 404s: The Hidden Problem
A soft 404 returns a 200 status code for a page that functions as a “not found” page. The server says “success,” but the content says “page not found” or shows an empty or minimal page.
This is like an empty envelope stamped “delivered.” The postal system thinks everything worked. But there is nothing inside.
Why soft 404s are problematic: Google wastes crawl budget on pages that should not exist in the index. Google’s systems attempt to detect soft 404s automatically, but they do not catch everything. Undetected soft 404s remain in the index, diluting your site’s quality signals.
Common soft 404 causes: error pages served with 200 status codes, search results pages for queries with zero results, category pages with no products, parameter variations leading to empty content, and CMS pages that exist structurally but have no content.
Search Console reports detected soft 404s in the Page Indexing report. Review these regularly and fix the underlying issues.
Fixes: return proper 404 status codes for non-existent content, noindex pages that might be soft 404s like empty search results and empty categories, and add content to thin pages or remove them entirely.
Server Error Codes: 500 and 503
Server errors indicate problems Google cannot solve by adjusting its crawling approach.
500 Internal Server Error means something went wrong on the server. Occasional 500s do not hurt rankings. Persistent 500s on important pages will eventually cause removal from the index.
503 Service Unavailable means the server is temporarily unable to handle the request. This is the correct response during planned maintenance.
For maintenance, return 503 with a Retry-After header indicating when Google should try again. This tells Google the downtime is temporary and intentional, not a sign of site problems.
The danger of extended 503s: if your site returns 503 for extended periods spanning days, Google will eventually start treating it as permanent unavailability. Keep maintenance windows short and use 503 correctly rather than showing a maintenance page with 200 status.
Redirect Chains: The Compounding Problem
A redirect chain occurs when URL A redirects to URL B, which redirects to URL C, and so on.
Each redirect in the chain introduces latency. Three redirects might add 300 to 500 milliseconds to page load time. Link equity diminishes slightly at each hop. While modern Google likely passes most equity through chains, there is no benefit to this inefficiency. Long chains with five or more redirects may be abandoned entirely. Googlebot might stop following redirects beyond a certain depth.
Fixing chains requires identifying them through crawl audits and updating redirects so every URL points directly to the final destination. If A redirects to B which redirects to C which redirects to D, update so A, B, and C all redirect directly to D.
Chain prevention: when updating redirects, always check if the destination is itself a redirect. Point to the final target directly.
Redirect Loops: The Complete Failure
A redirect loop occurs when redirects create a circle. A redirects to B, B redirects back to A. Or A redirects to B, B redirects to C, C redirects back to A.
Loops completely prevent page access. Users see error messages. Googlebot cannot reach the content. These are critical failures requiring immediate fixes.
Common loop causes: conflicting redirect rules where CMS redirects to URL A while server redirects A back to original, HTTPS and HTTP rules conflicting with www and non-www rules, geo-targeting rules conflicting with language rules, and load balancer configuration issues.
Detection: browser developer tools show redirect chains, crawl tools identify loops during site audits, and users report pages that will not load.
Immediate fix: audit all redirect sources, map out the full redirect path, remove or correct the rule creating the loop, and test thoroughly before deploying.
Monitoring and Maintenance
Search Console’s Coverage report shows pages with redirect issues and server errors. Monitor regularly for new issues.
Crawl tools like Screaming Frog and Sitebulb map redirects across your entire site. Run audits monthly for large sites, quarterly for smaller ones.
Log file analysis shows actual status codes served to Googlebot. Use this to verify redirect behavior rather than relying on testing tools alone.
Post-migration monitoring is critical. After any URL changes or migration, monitor redirect behavior closely for 30 days. Chains and loops often emerge from rule interactions that were not apparent during testing.
Status codes seem like technical minutiae until you realize a single misconfigured redirect can erase years of accumulated link equity, or a soft 404 pattern can keep thousands of worthless pages in Google’s index. Getting these basics right is foundational to everything else in SEO.
Sources
- Google Search Central: HTTP Status Codes – https://developers.google.com/search/docs/crawling-indexing/http-network-errors
- Google Search Central: Redirects and Google Search – https://developers.google.com/search/docs/crawling-indexing/301-redirects
- Google Search Console Help: Page Indexing Report – https://support.google.com/webmasters/answer/7440203
- Google Search Central: Soft 404 Errors – https://developers.google.com/search/docs/crawling-indexing/http-network-errors#soft-404-errors
- RFC 7231: HTTP Status Codes – https://www.rfc-editor.org/rfc/rfc7231#section-6