Certificate Expiry Calculator
Calculate the number of days until an SSL/TLS certificate or domain expires from its expiry date, with a renewal warning threshold.
Last reviewed by the Radiatus Cloud team
Calculate how many days remain until a certificate or domain expires.
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Calculate days until certificate expiry
SSL/TLS certificates and domain registrations have expiry dates, and letting one lapse causes security warnings or outages. This calculator works out how many days remain until a given expiry date and flags whether the certificate is valid, expiring soon or already expired, based on a warning threshold you set. Enter the expiry date and a number of days to warn within, such as thirty, and the tool tells you where you stand at a glance.
The expiry is treated as the end of the given day, and the calculation uses the current date in your browser.
Stay ahead of renewals
Certificate and domain expiries are a frequent cause of avoidable incidents, from browsers blocking a site with an expired certificate to a domain lapsing and being lost. Tracking days remaining lets you plan renewals well before the deadline. Modern certificates are often valid for only a short period, so automated renewal is strongly recommended, but a manual check remains a useful safeguard.
Use the warning threshold to match your renewal lead time, and check critical certificates regularly. This tool works from a date you provide and does not fetch any certificate. All calculation happens locally in your browser.
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Frequently Asked Questions
How is the days-remaining count calculated?
It compares the expiry date, treated as the end of that day, with the current date, and reports the whole days between them.
What does the warning threshold do?
If the days remaining fall at or below the threshold, the status shows as expiring soon, prompting you to renew in good time.
Does it check a live certificate?
No. It works from the expiry date you enter. To read a live certificate\'s date, inspect it in your browser or with a command-line tool first.
Why automate certificate renewal?
Modern certificates are often short-lived, so automated renewal avoids the risk of forgetting and causing an outage when one expires.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter the expiry date to see days remaining and status.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.