If you already have a battery:
Use the Battery Runtime Calculator to estimate how many hours or days it can power your devices. For office equipment or servers, use the UPS Runtime Calculator.
Battery & Backup Planning
Battery Calculators
Calculate battery backup runtime, size a battery bank for power outages, convert Ah to Wh, or estimate charge times with transparent, editable assumptions.
Available battery calculators
Battery Storage⏱️
Battery Runtime Calculator
Hours • Peukert Law • Inverter
Estimate how long your battery can power a load, with editable reserve, battery health and efficiency assumptions.
Explore Battery Runtime Calculator
Battery Storage🔋
Battery Size Calculator
Ah ↔ Wh • Voltage Sizing
Estimate the battery capacity needed for a load and backup time, with clear planning assumptions.
Explore Battery Size Calculator
Battery Storage🖥️
UPS Runtime Calculator
Minutes • VA to Watts • PF
Estimate how long a UPS can support your equipment from usable battery energy and load watts.
Explore UPS Runtime Calculator
Battery Storage🏢
UPS Battery Size Calculator
Ah • Inverter Efficiency • Surge
Calculate UPS battery Wh and Ah from load, backup time and editable planning assumptions.
Explore UPS Battery Size Calculator
Battery Storage⚡
Battery Capacity Calculator
Ah • Nominal Volts • Energy
Convert Ah, mAh, Wh and kWh using voltage, then estimate usable battery energy.
Explore Battery Capacity Calculator
Battery Storage🔌
Battery Charging Time Calculator
Hours • Amps • C-Rate
Estimate charging time from capacity, state of charge and charger output with editable battery-limit assumptions.
Explore Battery Charging Time Calculator
Battery Storage⛺
Portable Power Station Calculator
Wh • AC & DC Appliance Runtime
Estimate portable power station runtime or required capacity while checking continuous and startup output limits.
Explore Portable Power Station Calculator
Interactive Planning Journey
Recommended Battery & Energy Storage Engineering Workflow
Follow our 4-step engineering workflow to calculate, size, convert, and verify battery performance for backup outages and off-grid living:
1
🔋Size Required Capacity
Step 1 • Sizing
Calculate required nominal kWh and Ah for your connected load and target autonomy.
Launch Step 1
2
🧮Convert Ah & Usable Wh
Step 2 • Energy Math
Convert between Amp-hours, Watt-hours, and system voltages (12V, 24V, 48V).
Launch Step 2
3
⏱️Verify Outage Runtime
Step 3 • Runtime
Simulate exact backup duration (hours/minutes) with inverter efficiency and SOH derating.
Launch Step 3
4
⚡Calculate Recharge Time
Step 4 • Charging
Estimate charging hours from AC chargers or solar power with CC/CV taper allowances.
Launch Step 4
📜
Engineering Standards & Technical Methodology References
Calculations, electrical losses, and design safety margins adhere to recognized engineering guidelines:
NEC Article 706Energy Storage Systems (ESS)• National Electrical Code (NFPA 70)
Requirements for battery storage disconnects, circuit sizing, and ventilation in residential installations.
IEC 62619 / UL 1973Secondary Lithium Cells & Batteries Safety• IEC / Underwriters Laboratories
Safety requirements for industrial and residential lithium energy storage systems and BMS controls.
IEEE 1547-2018Standard for Interconnection & Interoperability• Institute of Electrical and Electronics Engineers
Grid-tie inverter synchronization, anti-islanding protection, and voltage/frequency ride-through.
Which battery calculator should I use?
If you are planning backup power:
Use the Battery Size Calculator to find the required kWh or Ah for your backup duration, or the Home Battery Size Calculator for household outages.
If you need unit conversions or charging estimates:
Use the Battery Capacity Calculator to convert Ah, mAh, Wh, and kWh, or the Battery Charging Time Calculator to estimate recharge hours.
Plan with the details that matter
Real battery performance depends on depth of discharge, battery chemistry, inverter efficiency, and ambient temperature. Our calculators expose every assumption so you can adjust them to your exact equipment.
Read the calculation methodology or review laboratory sources & standards.