Uptime/SLA calculator
Calculate a downtime budget or reverse an entered duration into availability. Choose a period and compare 30-day and 365-day budgets. No uptime measurement or SLA certification. Compare seconds, minutes and hours for the selected period. The comparison table applies the same availability rate to fixed day, week, month and year lengths.
Free to use. No email or account required.
Bookmark
Bookmark this tool
Save this short link in your browser’s bookmarks.
Paste this link into the address of a new or existing bookmark.
On desktop, drag Uptime/SLA calculator to your bookmarks bar.
Only the tool’s link is shared. Your inputs and results are not included.
Share
Your inputs
Edit the example inputs to match your task. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
Formula
Input and formula key
Your result
Complete the inputs to see your result.
Sources
- Google SRE — error budget policy (availability context)Sources reviewed: 2026-11-06
Assumptions and limitations
An arithmetic budget, not uptime measurement or an SLA contract interpretation. Calendar months, leap years, exclusions and contractual rounding are not modeled.
How to use this tool
Set up the inputs
Enter availability between 0 and 100 percent and Calculate. Choose a target budget or reverse calculation from entered downtime. Set the period in days and the downtime unit; entered downtime cannot exceed the period.
Understand the result
Compare seconds, minutes and hours for the selected period. The comparison table applies the same availability rate to fixed day, week, month and year lengths.
Worked examples
-
Budget downtime for a 30-day month
30 × 86,400 × (1 − 99.9 / 100) = 2,592 s = 43.2 min.
Frequently asked questions
What are the limits of this tool?
An arithmetic budget, not uptime measurement or an SLA contract interpretation. Calendar months, leap years, exclusions and contractual rounding are not modeled.
How does the calculation work?
Allowed downtime = selected period seconds × (1 − availability/100). Reverse mode uses availability = 100 × (1 − downtime/period seconds). A custom period is 1–3,660 whole days. The 30-day and 365-day comparisons are always seconds, not measured or contractual availability.
Processing and privacy
The calculation or transformation runs in your browser. The tool does not send its input values or generated output to an application server. Loading a page still makes infrastructure requests; optional analytics and Google consent messages have separate controls.
Privacy Policy. Privacy & preferences in the footer controls optional analytics.
Help and feedback
Consult the linked sources for definitions and reference data. Contact Support if you have a question or notice a problem.
Read about calculation methods · Report a problem to emonster
Related tools
Explore this subject: Technology
Cron tester
Preview five-field Unix cron schedules with a time zone, reference time, presets and occurrence count.
Time duration
Compare clock differences and elapsed time, including overnight shifts and daylight saving changes.
Downtime cost calculator
Estimate lost revenue from your hourly revenue, downtime and affected percentage.