BackupTime

BackupTime helps you plan how long your gear can run from a UPS, battery, portable power station, or power bank — before the lights go out.

Enter capacity in Wh or mAh, add voltage, efficiency, and reserve, then build a realistic load from multiple devices. BackupTime calculates usable energy, total load, estimated runtime, and an expected range that accounts for real-world variation.

Key features
• Wh and mAh capacity input with voltage conversion
• Efficiency and protected reserve applied before runtime
• Multiple devices and quantities in one load scenario
• Normal and economy power modes
• Economy / normal / peak runtime comparison table
• Reusable battery and device library
• Saved calculations with search, filters, sorting, pin, archive, duplicate, and undo delete
• Versioned JSON export and validated merge/replace import
• Fully offline — no accounts, ads, analytics, or internet permission
• Light, dark, system, and optional Dynamic Color themes
• Phone and tablet adaptive navigation

Built for real planning
Whether you are preparing for outages, packing for travel, or sizing backup power, BackupTime keeps every estimate transparent: inputs, formula, usable energy, warnings, and assumptions stay visible.

Privacy first
All data stays on your device unless you explicitly export a JSON backup through the system document picker. There are no trackers, subscriptions, or cloud sync.

Results are estimates. Always verify manufacturer capacity and continuous/surge power ratings for your battery or inverter.