UPS Load Calculator – Calculate UPS Capacity & Runtime for Your Equipment

Make sure your UPS can handle your equipment with our UPS Load Calculator. Enter the wattage of connected devices and your UPS battery rating to determine total load, required VA rating, and estimated backup runtime.

Connected Devices

UPS Specifications

UPS VA Rating

Battery Voltage (V)

Battery Capacity (Ah)

Power Factor

Efficiency (%)

UPS Load Analysis

Enter values and click Calculate to see results

UPS Calculation Formulas

Total Watts = Σ(Device Watts × Quantity)

Total VA = Total Watts ÷ Power Factor

Load % = (Total VA ÷ UPS VA Rating) × 100

Runtime (hrs) = (Battery V × Battery Ah × Efficiency) ÷ Total Watts

Power Factor: Most electronics have PF between 0.6-0.9. Higher PF means more efficient power usage.

How to Calculate UPS Load Capacity

Add Your Devices

Enter each device's wattage or select from presets like PC, monitor, router, and NAS.

Enter UPS Specifications

Input your UPS VA rating, battery voltage, and amp-hour capacity for accurate analysis.

Get Load Analysis

See total load percentage, estimated runtime, and recommended UPS size for your setup.

Why Use This UPS Load Calculator

Multi-Device Support

Add unlimited devices with quantity support and quick-select presets for common equipment.

VA to Watts Conversion

Automatically converts between VA and watts using power factor for accurate load assessment.

Load Percentage Warning

Visual indicators show if your UPS is underloaded, optimally loaded, or dangerously overloaded.

Runtime Estimation

Calculates expected backup time based on battery capacity and total connected load.

Common Device Power Consumption

Device	Typical Watts	Device	Typical Watts
Desktop PC	300-500W	Router	10-15W
Laptop	45-90W	Modem	10-20W
Monitor 24"	25-35W	NAS	30-60W
Monitor 27"	35-50W	TV 55"	80-120W
Gaming Console	100-200W	Network Switch	20-40W

Frequently Asked Questions

What size UPS do I need for my PC?

Add up all device watts and multiply by 1.25 for headroom. A gaming PC (400W) + monitor (40W) + router (15W) = 455W × 1.25 = 569W minimum. Choose a UPS rated at least 700-800W (1000-1200VA).

What is the difference between VA and watts?

VA (volt-amps) is apparent power, while watts is real power. Watts = VA × Power Factor. Most electronics have PF of 0.6-0.9, so a 1000VA UPS typically delivers 600-900 watts of real power.

How much load should I put on my UPS?

Keep UPS load between 50-80% of rated capacity for optimal efficiency and battery life. Running at 100% reduces runtime and stresses the battery. Overloading (>100%) will trip the UPS or damage it.

How long will my UPS keep devices running?

Runtime depends on battery capacity and load. A typical 1000VA UPS with 7Ah battery runs a 200W load for 15-20 minutes. Halving the load roughly doubles runtime. For hours of backup, add external battery packs.

Should I run my laser printer on UPS?

No. Laser printers draw 5-10× their rated power during warm-up, which can overload or damage a UPS. Use a surge protector instead. Inkjet printers are safe to connect to UPS.

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