Let’s Encrypt is continuing a push toward tighter security by reducing free SSL/TLS certificate lifetimes from 90 days to 64 days, starting February 10, 2027. For administrators already implementing modern ACME clients that support ARI (ACME Renewal Information), the change should be seamless. For those still relying on hardcoded renewal schedules or manual processes, February will be the deadline to update before certificates start expiring unexpectedly.

Starting on October 14, Let’s Encrypt will begin testing the 64-day certificates, and interested users can opt in to test their setups before production goes live.

Prior to Let’s Encrypt’s launch in early 2016, certificates were often issued for as long as one to three years. The service started with 90-day certificates to force renewal automation that didn’t previously exist. Shorter certificate validity periods limited vulnerabilities from private key thefts and encouraged accelerated HTTPS adoption across the web.

This move shook  industry norms at the time, but by limiting the certificate lifetime, the certs are less likely to cause damage if compromised or assigned in error. The move down to 64 days continues this logic, and the lifespans will only continue to get shorter as time goes on, with 45-day defaults planned to follow in 2028.

Just as the initial rollout of Let’s Encrypt aimed to push users toward HTTPS, the shortened certificate windows are aimed at moving users to full ACME automation. The ACME protocol, and, more specifically, ARI (ACME Renewal Information), allows the certificate authority to tell the client when it’s time to renew. Although ARI does this, many deployments are still stuck on scripted update intervals that trigger at fixed offsets like “60 days before expiration.”