TTL Calculator

Humanize DNS TTL values and compute cache expiry times from now or specific dates

TTL Humanization: Convert seconds to human-readable formats like "2 hours" or "1 day".
Cache Expiry: Calculate when DNS records will expire from resolver caches.
TTL Guidelines: Get recommendations based on record stability and use case.

Common TTL Values

TTL by Use Case

TTL Analysis

1 hour medium
3,600 seconds

Cache Expiry Times

From Now
Sep 28, 2025, 05:46:34 PM UTC
in 1 hours

Summary

  • Medium TTL - balanced between performance and flexibility

TTL Guidelines by Category

Very Short (< 5 min)
High DNS load, instant propagation
Short (5 min - 1 hr)
Frequent changes, good for testing
Medium (1 hr - 1 day)
Balanced performance and flexibility
Long (1 day - 1 week)
Stable records, reduced DNS queries
Very Long (> 1 week)
Infrastructure, rarely changes

TTL Trade-offs

Lower TTLs allow faster propagation of DNS changes but increase DNS query load. Higher TTLs reduce DNS traffic but slow down change propagation. Balance based on your needs.

Cache Behavior

DNS resolvers cache records for the TTL duration. Once expired, they must query authoritative servers again. Some resolvers may cache slightly longer or shorter than the exact TTL.

Change Planning

Before making DNS changes, consider lowering TTLs in advance. This reduces the time users see old records. After changes stabilize, you can increase TTLs again.

Monitoring Impact

Monitor DNS query volumes when changing TTLs. Very short TTLs can significantly increase load on authoritative servers and may impact DNS provider costs.