Engineering Calculators for Power, Electrical & Energy Systems
Practical engineering calculators for power conversion, electrical sizing, energy systems, UPS, solar, HVAC, motors, and equipment planning.
Built for practical engineering calculations. Where applicable, formulas reference standards such as IEEE, IEC, NEC, and ASHRAE.
Start with a scenario
Start with your task and we'll guide you to the right calculator.
How Long Will UPS Last
Estimate UPS backup time from load and battery capacity, then continue into full sizing tools.
Start Scenario ->UPS for CCTV
Size UPS capacity for CCTV cameras, NVR, and PoE switches with practical charts.
Start Scenario ->What Size UPS for Home Office
Pick the right UPS size for desks, monitors, routers, and home-office gear.
Start Scenario ->Portable Power for Home Outage
Estimate Wh tier for a portable power station during a home outage.
Start Scenario ->Popular Calculators
Quick access to commonly used calculators for electrical power, energy systems, and equipment sizing.
kVA to Amps Calculator
Convert kVA to amps for single-phase and three-phase systems.
Use Calculator ->3-Phase Power Calculator
Calculate three-phase power, current, and voltage relationships.
Use Calculator ->Circuit Breaker Size Calculator
Estimate breaker amp rating for branch and feeder loads.
Use Calculator ->Browse by Category
Use high-intent category pages to jump straight into the right calculator workflow.
Power Calculator
Power conversion, three-phase, power factor, load, and transformer calculations.
Open Category ->Electrical Calculators
Current, breaker, cable, voltage-drop, motor, and protection calculations.
Open Category ->Pneumatics Calculators
Cylinder force, compressor CFM, pipe sizing, and compressed air workflows.
Open Category ->HVAC Calculator
Capacity, psychrometrics, ACH/CFM, and duct sizing for facility environments.
Open Category ->Solar Calculator
PV array, production, MPPT, storage, and inverter sizing workflows.
Open Category ->Backup Power Calculator
Portable power station Wh, charge time, and home outage sizing workflows.
Open Category ->Featured Workflows
Follow these step-by-step workflows to combine calculators for common engineering tasks.
Featured Engineering Guides
Start with these core guides. Each one pairs formulas and worked examples with the matching calculator workflow.
How to Calculate Factory Load
Step-by-step electrical load calculation for facilities: diversity factors, power factor, breaker sizing, and worked examples.
Read Guide → Use Factory Load Calculator →3-Phase Power Explained
How three-phase power works, when to use it, calculation methods, and practical examples for electrical systems.
Read Guide → Use 3 Phase Power Calculator →Transformer Sizing Guide
Size transformers with formulas, examples, and safety margins based on actual load requirements.
Read Guide → Use Transformer Calculator →Motor Starting Current & Protection
Starting current, overload vs short-circuit protection, and worked examples—pair with motor FLA, cable, and breaker tools.
Read Guide → Motor FLA Calculator → Electrical Calculators Hub →Built for Practical Engineering
CalcPanel focuses on practical engineering calculations for power conversion, electrical sizing, energy systems, and equipment planning. Tools are designed to give fast, transparent estimates you can take into the next design or verification step.
Engineering Standards
Calculators use established engineering formulas and, where applicable, reference standards such as IEEE, IEC, NEC, and ASHRAE.
Real-World Scenarios
Examples and workflows mirror common field tasks—load screening, UPS runtime, cable checks, and equipment sizing—not abstract textbook-only cases.
Clear Boundaries
Results are engineering estimates and guidance. They do not replace project-specific professional design, code review, or local regulatory requirements.
Frequently Asked Questions
Are CalcPanel calculators free?
Yes. CalcPanel calculators are free to use with no registration required. Open a tool, enter your values, and get results instantly.
How accurate are the calculations?
Results are based on established engineering formulas and stated assumptions. Treat them as guidance for screening and planning—not as sealed drawings or legally binding design documents. Always verify critical applications with a qualified professional.
Which engineering standards are used?
Calculators use established engineering formulas and, where applicable, reference standards such as IEEE, IEC, NEC, and ASHRAE. Not every tool applies every standard; check the formula notes on each calculator page.
Do calculations replace professional engineering design?
No. CalcPanel provides engineering estimates and practical guidance. They do not replace project-specific professional design, code review, or local regulatory requirements.
How is my calculation data handled?
Most calculator inputs are processed locally in your browser unless a feature explicitly states otherwise. We do not require an account to use the tools. Site analytics may record page and interaction events; see our Privacy Policy for details.