GA4. File download events. Count spec sheets and sizing guides.

What this means for your store

A spec sheet download often precedes a bulk order. file_download records when someone pulls a file from your site. Standard params: file_name, file_extension, link_url. Enhanced measurement catches common extensions (pdf, xlsx). Explicit events give cleaner names and work with signed CDN URLs.

Scenario on a real storefront

BoltWorks, an industrial parts B2B store, hosts a torque spec PDF per SKU. Fire on the download button click, before the browser opens the file:

// PDP button - "Download spec sheet (PDF)"
document.querySelector('.spec-download').addEventListener('click', (e) => {
  const url = e.currentTarget.href;
  gtag('event', 'file_download', {
    file_name: 'SKU-4420-torque-spec.pdf',
    file_extension: 'pdf',
    link_url: url,
    link_text: 'Download spec sheet',
    content_type: 'product_spec',  // custom param
  });
});

// Enhanced measurement auto-tracks links ending in .pdf
// Admin → Data streams → Web → Enhanced measurement → File downloads

// GTM: Click trigger on CSS .download-asset + GA4 Event tag

What to do next

• Mark spec downloads as a key event on B2B storefronts - they often precede generate_lead.
• Report file_name by landing page to see which PDPs drive research, not impulse buys.
• Exclude invoice and packing-slip PDFs from triggers - they pollute the metric.

Bottom line

file_download captures research intent before checkout. Use explicit events for named assets. Audit enhanced measurement so internal PDFs do not count.