Discovery
LOWSitemap respects 50 MiB / 50,000-URL caps per document
No fetched sitemap document exceeds 50 MiB or 50,000 URLs. Over-cap sitemaps are silently dropped — neither byte overflow nor entry overflow surfaces a crawler error.
What this check looks for
sitemaps.org caps each individual sitemap document at 50 MiB uncompressed and 50,000 URLs. Over-cap documents must be split into a sitemap index. We check both numbers for every resolved sitemap resource and report any breach with the actual size / count.
Which AI surfaces it affects
- Google AI Mode (UCP)60
- Microsoft Copilot50
- ChatGPT (ACP)30
- Perplexity30
- Meta AI30
Weighted against the live specs — ACP 2026-04-17, UCP 2026-04-08.
How to fix it
Split over-cap sitemaps into a sitemap index
Shopify
Developer- Shopify auto-splits sitemaps by section and never exceeds the caps. If failing on Shopify, you're auditing a custom-proxy response — fix the proxy.
BigCommerce
Developer- BigCommerce's `/xmlsitemap.php` paginates automatically. If failing, a CDN/edge worker is concatenating responses — inspect it.
WooCommerce
A few minutes- Yoast / Rank Math both split at 1,000 URLs by default. If failing, your plugin is misconfigured — bump the per-page cap down or check for a custom sitemap generator.
Custom / headless
Developer- Paginate the sitemap and emit a sitemap index referencing each page.
// Emit a sitemap index when over 50,000 URLs
const PER_PAGE = 40_000;
for (let i = 0; i < products.length; i += PER_PAGE) {
writeSitemap(`/sitemap_products_${i / PER_PAGE + 1}.xml`, products.slice(i, i + PER_PAGE));
}
writeSitemapIndex('/sitemap.xml', allPageUrls);The spec it's pinned to
sitemaps.org — Sitemap size limits
The sitemaps.org protocol caps each sitemap document at 50 MiB uncompressed and 50,000 URLs. Over-cap documents must be split into a sitemap index.
Does your store pass this check?
Run the full audit — 82 checks across five AI shopping surfaces. Most tools only check whether you get mentioned; we check whether an agent can buy from you.