Reliability & Operations

Combined SLA Calculator

Estimate availability for independent serial dependencies or parallel alternatives.

Calculations run in your browser. The tool does not send your inputs to a server.

01Your inputs

Local workspace

Start with the sample below, or enter your own values.

Availability percentagesThe sample is editable. Keep the input format consistent with the action you choose.

Architecture

02Your result

Your result will appear here. Choose an action after checking your inputs.

A quick guide

How to use this tool

Check the example and the unit beside each input.
Enter your values and choose Calculate.
Review the result and assumptions, then copy what you need.

Reset example restores the starting values. Clear removes text and number inputs, returns choices to their first valid option, and removes the result.

Reference guide

Explanation and worked examples

Both formulas assume independent component availability. Serial requires every component; parallel requires any one alone to serve the workload with ideal failover. Shared power, network, software and failover failures need a richer dependency model.

Use in day-to-day IT work

Estimate the effect of independent dependencies or redundant components on a service target.

Checks before applying the result

Assuming independent component availability, two 99.9% serial dependencies yield 99.8001%. Two independent 99% alternatives yield 99.99% only when either alone can serve the workload with ideal failover.
Shared authentication, network, power, deployment and failover failures require a dependency model beyond either independent formula.

New to the terminology?

SLA: A service agreement that defines a target and how it is measured.
RTO: Recovery Time Objective: how quickly service must be restored.
RPO: Recovery Point Objective: how much recent data loss is acceptable.

Keep exploring

How calculations work and where the models stop →