Wattmargin: Outage Planner

Backup Power Scenario Lab

$3.99 · Designed for iPad. Not verified for macOS.

Plan an outage with your own appliances: battery runtime with real losses, generator fuel from your manual, load schedules, a checklist, and backups. One purchase. Wattmargin turns your appliances and your backup-power source into a practical, private outage plan. Enter a battery power station, portable generator, vehicle inverter, or UPS, list what you want to keep running, and see running and starting watts, battery runtime or generator fuel, and what to switch off first. No account, no subscription. RUNTIME AND FUEL PLANNER • Hour-by-hour outage timeline for the length and start time you choose • Battery runtime that counts inverter efficiency, inverter idle draw, depth of discharge, and your reserve • Peukert discharge-rate effect for lead-acid batteries (off for lithium) • Optional daily recharge from solar panels or a vehicle • Generator fuel for the whole outage, fuel per day, refuels, and hours per tank, interpolated from the runtime figures in your manual so light loads still burn fuel • Chart of usable energy or fuel used over the outage LOAD LIST WITH SCHEDULES • Running watts, starting watts, power factor, duty cycle, priority, room, and notes for every appliance • Set the hours each load runs, or spread its hours across the day • 24-hour load profile chart • Start from typical values for 20 common appliances, then replace them with your label readings • Include, exclude, duplicate, or delete loads CAPACITY CHECKS • Running load against continuous output and the worst single startup against surge output • Apparent load in VA against a UPS or inverter VA rating • Output derating for heat, altitude, or aging • Plain-language warnings when the plan is tight or over a limit SCENARIO BENCH • Compare your current plan, everything catalogued, must-run plus rotating loads, and must-run loads only • Load-shedding order that protects must-run equipment and shows the runtime each switch-off gains OUTAGE CHECKLIST AND NOTES • Editable checklist with suggested preparation items, progress, and a reset for the next outage • Household notes and a circuit directory linked to your loads EXPORT AND BACKUP • Multi-page PDF plan with source, loads, timeline, scenarios, checklist, notes, and circuits • CSV export of the load list • JSON backup and restore; your current plan is kept as a safety copy before any restore PRIVATE BY DESIGN No account, ads, analytics, or developer-operated cloud service. Your plan stays on your device unless you export it. The only network action is an optional link to the U.S. Consumer Product Safety Commission website. IMPORTANT Wattmargin gives planning estimates from the ratings you enter. Real runtime depends on temperature, battery age, fuel, and equipment condition. It is not an installation guide or a substitute for manufacturer instructions, electrical codes, permits, or a qualified professional. Never run a portable generator inside a home, garage, basement, shed, porch, or carport; keep it outdoors at least 20 feet from the home with exhaust directed away. Never backfeed home wiring through a wall outlet.

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Wattmargin 2.0 is a major upgrade built around your own equipment. • New Runtime planner: hour-by-hour outage timeline, battery runtime with inverter losses, idle draw, depth of discharge, and Peukert for lead-acid • New generator fuel planner from your manual's runtime points, with fuel per day and refuels • Appliance schedules, power factor and VA checks, and a 24-hour load profile • Typical values for 20 common appliances to get started • Editable outage checklist with suggested items and household notes • CSV export, JSON backup and restore, and a multi-page PDF • New installs start with an empty plan; the example is clearly labelled • Removed the generic image cards from the guide • Fixes: loads can be deleted, plan name and notes are editable, start-over actions now keep a safety copy, the PDF no longer cuts off long lists, and iPad layouts no longer stretch

Version 2.0

The developer, Robert Corbin, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

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    Accessibility

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    Information

    Seller
    Robert Corbin
    Size
    5.3 MB
    Category
    Utilities
    Compatibility
    Requires iOS 17.0 or later.
    • iPhone
      Requires iOS 17.0 or later.
    • iPad
      Requires iPadOS 17.0 or later.
    • Mac
      Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    English
    Age Rating
    4+
    Copyright
    © 2026 Robert Corbin
  • Developer Website
  • Privacy Policy

    • Supports

    • Family Sharing

      Up to six family members can use this app with Family Sharing enabled.

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