DNS TTL Converter (Seconds to Human-Readable)
Convert a DNS TTL in seconds to a readable duration like 1d 2h, with a plain-English note on its caching impact. Runs in your browser.
Cache impact: Short — changes propagate within an hour. Good default while actively making changes.
About this tool
A DNS record's TTL (time to live) is the number of seconds that resolvers and clients are allowed to cache it before checking again. DNS zone files express it as a raw integer — 3600, 86400, 300 — which is easy to misread, so this tool converts any TTL into a clear duration like '1d' or '1h 30m' and explains what that value means in practice. The trade-off behind the number is the whole point: a short TTL means changes propagate quickly but every client re-queries often, adding load and a touch of latency; a long TTL means excellent caching and minimal queries but a record change can take that long to reach everyone. The common pattern is to lower the TTL a day or two before a planned migration, make the change, confirm it, then raise it again. The conversion is exact and runs entirely in your browser.
How to use it
- Enter the TTL value in seconds, or pick a common preset.
- Read the human-readable duration.
- Check the cache-impact note to see how it affects propagation and query load.
- Lower the TTL ahead of a planned DNS change, then raise it afterward.
Frequently asked questions
- What does DNS TTL actually control?
- How long a resolver or client may cache the record before it must ask the authoritative server again. A TTL of 3600 means cached for up to one hour. It does not change the record's value — only how long stale copies may linger.
- What TTL should I use?
- For stable records, a longer TTL (a few hours to a day) reduces query load and improves resilience. For records you may change soon, drop to 300 seconds (5 minutes) so updates propagate fast. Many providers default to 3600 (1 hour) as a balance.
- Why do my DNS changes take so long to appear?
- Because resolvers cache the old record for up to its previous TTL. If the record had a TTL of 86400 when it was cached, some resolvers may serve the old value for nearly a day even after you change it. Lowering the TTL in advance avoids this.
- Does a lower TTL hurt performance?
- Slightly. Shorter TTLs cause more frequent lookups, which adds a small amount of latency on cache misses and more load on the authoritative servers. For most sites the effect is negligible; for very high-traffic domains it is worth tuning.
- What is a sensible TTL before a migration?
- Lower it to 300 seconds (5 minutes) at least one full old-TTL period before the change, so caches expire and pick up the short value. After the migration is verified, raise it back to your normal TTL.
- Is anything uploaded?
- No. The conversion is pure arithmetic in your browser with no network request.