Uptime Calculator
Tính downtime cho phép theo mức SLA uptime
Downtime tối đa cho phép để đạt mức uptime đã chọn.
Uptime SLA Calculator: Allowed Downtime by Percentage
The uptime SLA calculator converts any availability percentage into concrete downtime figures across every time horizon — from daily minutes to annual hours. Whether you are drafting a service-level agreement, evaluating a cloud provider's SLA, or setting internal reliability targets, this tool gives you the exact numbers you need in seconds.
Benefits
Turning an abstract percentage into real downtime figures makes SLA commitments tangible and actionable for both technical and non-technical stakeholders.
- Instant clarity: See exactly how many minutes or hours of downtime a given SLA permits — no manual math required.
- Multi-period breakdown: Compare allowed downtime per day, week, month, and year side by side.
- Better SLA negotiation: Arrive at vendor discussions with precise numbers rather than vague percentages.
- Maintenance window planning: Know how much downtime budget remains this month before breaching your SLA.
- Error budget foundation: Use the results as the starting point for SLO and error-budget calculations in your reliability engineering practice.
Use cases
This downtime calculator is used across engineering, operations, and procurement roles wherever uptime guarantees matter.
- SRE and DevOps teams: Define error budgets and set realistic SLOs grounded in actual time allowances.
- IT procurement: Compare hosting or cloud providers by translating their SLA percentages into downtime you can feel.
- Incident post-mortems: Check whether an outage duration exceeded the monthly or yearly downtime allowance.
- Contract review: Validate that an SLA clause in a vendor agreement is as strong as it sounds.
- Executive reporting: Present system availability data in hours and minutes, which are more meaningful to leadership than percentages alone.
How to use
The calculator requires no sign-up and produces results instantly.
- Enter your target uptime percentage in the input field (for example, 99.95).
- The tool immediately displays the maximum allowed downtime per day, week, month, and year.
- Use the preset buttons for the most common SLA tiers: 99% (two nines), 99.9% (three nines), 99.99% (four nines), and 99.999% (five nines).
- Copy the results into your SLA document, runbook, or reliability dashboard as needed.
Frequently asked questions
How much downtime does 99.9% uptime allow per year? A 99.9% SLA permits approximately 8 hours and 45 minutes of downtime per year, or about 43 minutes per month.
What is the difference between four nines and five nines? 99.99% (four nines) allows roughly 52 minutes of downtime per year, while 99.999% (five nines) allows only about 5 minutes — a standard typically reserved for financial systems and critical telecommunications infrastructure.
Can I enter a custom uptime percentage that is not a standard SLA tier? Yes, you can enter any value between 0 and 100, including non-standard figures like 99.95% or 99.5%, and the tool will calculate the corresponding downtime across all periods.
Does the calculator account for leap years? Calculations use a standard 365-day year. For a leap year, the annual downtime allowance will be slightly higher; multiply the daily figure by 366 to get an adjusted annual total.