This tool helps engineers and operators model system availability and evaluate designs before deployment. It calculates availability for various configurations, estimates device reliability, and allows users to build and visualize complex systems. Generate professional PDF reports and review key definitions for availability and reliability.
1.5
August 27, 2026
Version 1.5 connects individual Device assumptions to complete mission decisions. TRANSPARENT DEVICE AVAILABILITY - Review a complete calculation breakdown: base MTBF, redundant-power benefit, spare logistics, EOL delay, eligible support benefit, hands-on repair time, and modeled restoration time. - Edit app-wide defaults for generic Device MTBF, redundant power, logistics, EOL sourcing, and support-agreement behavior. - See exactly when support changes the result. Support reduces eligible logistics and EOL delay only; it never reduces hands-on repair time. - Preserve the assumptions and MTBF provenance used by every saved Device, even when app-wide defaults later change. REUSE REAL DEVICE DATA - Select saved Devices directly as named Components in Series, Parallel, N:M, and Cross-Connected topologies. - Preserve Device names, availability, MTBF, and provenance through Blocks, Systems, exports, imports, and edits. NEW MISSION RELIABILITY - Evaluate whether a saved Device, Block, or System can complete a continuous mission measured in hours, days, or weeks without a service interruption. - Use stored MTBF when available, or explicitly model availability-only inputs using average restoration time or a reliability reference period. - Keep strict MTBF validation when assumptions are not appropriate. - Compare Mission Success, Interruption Risk, any-Component failure probability, expected failed Components, and the weakest contributor. - Apply existing Series, Parallel, heterogeneous N:M, Cross-Connected, Stage, and Handoff logic to mission survival. - See clear provided, estimated, assumption-based, and mixed data-quality labels. BETTER GUIDANCE - Follow an expanded Guided Tour from Device calculation and reuse through complex System construction, Live Modeling, SLO Analysis, System Comparison, and Mission Reliability. - Review new formulas, assumptions, limitations, worked examples, and Reliability Block Diagram guidance in Reference. - Benefit from additional layout, naming, and consistency improvements across iPhone and iPad. Mission Reliability uses a constant-rate, independent-failure model with no repair during the mission. Availability-only methods require an explicit assumption and are clearly labeled as approximate.
MoreSLO/SLA Calc is used by engineers and operators to model system availability and evaluate designs before deployment. It helps calculate availability for various configurations and estimate device reliability.
It calculates availability for series, parallel, and N:M designs. It can also estimate device availability using metrics like MTBF, MTTR, spare availability, and EOL status.
Yes, you can save devices and subsystems as reusable Blocks. These Blocks can then be combined into larger Systems, allowing for efficient modeling of complex architectures.
Yes, SLO/SLA Calc works offline. Saved Blocks and Systems are stored locally on your device, and no account is required to use the app.
SLO/SLA Calc can generate and share professional PDF system reports. These reports help visualize the resulting architecture and compare performance against a target SLO.
SLO/SLA Calc is a paid application priced at $1.99.
The latest version, 1.2, was released on July 19, 2026, indicating recent development activity. The app was initially released on July 16, 2026.
No, SLO/SLA Calc does not contain advertisements. It is a paid application that offers an ad-free experience.