UPS Power Supply Calculator
Sum of all connected devices' wattage (e.g., PC, monitor, router).
How long you need your devices to run on battery power.
Typical UPS efficiency is 85-95%. Lower efficiency means more battery drain.
Voltage of a single battery cell in the UPS (e.g., 12V for common lead-acid batteries).
Ratio of real power (Watts) to apparent power (VA). Typical for PCs is 0.6-0.7.
Adds extra capacity for future expansion or unexpected load spikes.
Calculation Results:
Please enter your values and click "Calculate" to see the recommended UPS specifications.
Error:
Please enter valid positive numbers for all fields. Efficiency and Power Factor should be within their respective ranges.'; return; } var runtimeHours = desiredRuntimeMinutes / 60; var efficiencyDecimal = upsEfficiency / 100; var safetyBufferDecimal = safetyBuffer / 100; // 1. Calculate Required UPS VA Rating // VA = Watts / Power Factor var loadVA = totalDeviceWatts / powerFactor; // Add safety buffer var recommendedUPS_VA = loadVA * (1 + safetyBufferDecimal); // 2. Calculate Required Battery Energy (Wh) // Energy (Wh) = (Total Load Watts * Runtime Hours) / UPS Efficiency // This accounts for the energy lost by the UPS itself when running on battery var requiredBatteryWh = (totalDeviceWatts * runtimeHours) / efficiencyDecimal; // 3. Calculate Required Battery Capacity (Ah) // Ah = Wh / Battery Voltage var requiredBatteryAh = requiredBatteryWh / batteryVoltage; resultDiv.innerHTML = `Recommended UPS Specifications:
Recommended UPS VA Rating: ${recommendedUPS_VA.toFixed(0)} VA Required Total Battery Energy: ${requiredBatteryWh.toFixed(0)} Wh Required Total Battery Capacity: ${requiredBatteryAh.toFixed(1)} Ah Note: The Ah rating is the total capacity needed. If your UPS uses multiple 12V batteries in series (e.g., for 24V or 48V systems), the individual battery Ah rating will be the same as the total Ah, but you'll need multiple batteries. If batteries are in parallel, their Ah ratings add up. Consult your UPS manual for battery configuration. `; }Understanding and Sizing Your UPS Power Supply
An Uninterruptible Power Supply (UPS) is a critical device that provides emergency power to a load when the input power source or mains power fails. It's essential for protecting sensitive electronics like computers, servers, and networking equipment from power outages, surges, and sags, ensuring data integrity and system uptime.
Why Do You Need a UPS?
- Data Protection: Prevents data loss and corruption during sudden power failures.
- Equipment Protection: Shields electronics from damaging power fluctuations like surges and brownouts.
- System Uptime: Allows for graceful shutdowns of systems, preventing potential hardware damage or lengthy recovery processes.
- Business Continuity: Maintains operation of critical systems during short power interruptions.
Key Terms Explained:
To effectively size a UPS, it's important to understand the following terms:
- Watts (W): This is the "real power" consumed by your devices. It's the actual power used to perform work. When you look at the power rating of your computer, monitor, or server, it's usually expressed in Watts.
- Volt-Amperes (VA): This is the "apparent power" and represents the total power in an AC circuit, including both real power (Watts) and reactive power. UPS units are typically rated in VA.
- Power Factor (PF): The ratio of real power (Watts) to apparent power (VA). It's a number between 0 and 1. For most computer equipment, the power factor is between 0.6 and 0.7. A higher power factor means the device is more efficient in using the apparent power.
VA = Watts / Power Factor. - Runtime (Minutes/Hours): The duration for which the UPS can supply power to the connected devices during an outage. This is a crucial factor based on how long you need to keep your systems running or perform a graceful shutdown.
- UPS Efficiency (%): No power conversion is 100% efficient. A UPS consumes some power itself to operate and convert battery power to AC. This efficiency rating (typically 85-95%) affects how much battery energy is actually delivered to your devices.
- Battery Voltage (V): The voltage of the individual batteries used within the UPS. Common values are 12V. Larger UPS systems might use multiple batteries in series to achieve higher voltages (e.g., 24V, 48V).
- Battery Capacity (Ah – Amp-hours): This measures how much charge a battery can deliver over time. For example, a 100 Ah battery can theoretically deliver 100 Amps for one hour, or 10 Amps for 10 hours.
- Battery Energy (Wh – Watt-hours): This is the total energy stored in a battery. It's calculated as
Ah * V. This is often a more direct way to compare battery energy across different voltages.
How to Use the UPS Power Supply Calculator:
- Total Device Power Consumption (Watts): Add up the wattage of all devices you plan to connect to the UPS. You can usually find this on the device's power supply, label, or in its specifications. For a typical desktop PC, monitor, and router, this might be 200-500 Watts.
- Desired Runtime (Minutes): Decide how long you need your devices to stay powered. For a graceful shutdown, 5-10 minutes might suffice. For continued operation during short outages, you might need 15-30 minutes or more.
- UPS Efficiency (%): Most modern UPS units have an efficiency of 85-95%. If you don't know, 90% is a reasonable default.
- Battery Voltage (V): For most consumer-grade UPS units, the internal batteries are 12V. If you're dealing with a larger, modular system, you might need to check the battery specifications.
- Load Power Factor: For typical computer loads, a power factor of 0.6 to 0.7 is common. If your equipment has Active Power Factor Correction (PFC), it might be closer to 0.9 or 0.95. If unsure, 0.7 is a safe general estimate.
- Safety Buffer for UPS Sizing (%): It's always wise to add a buffer (e.g., 15-25%) to your calculated VA rating. This accounts for potential future expansion, unexpected load spikes, and ensures the UPS isn't constantly running at its maximum capacity, which can extend its lifespan.
Interpreting the Results:
- Recommended UPS VA Rating: This is the minimum VA rating your UPS should have. Always round up to the nearest standard UPS size available (e.g., if you need 1200 VA, look for a 1500 VA UPS).
- Required Total Battery Energy (Wh) & Capacity (Ah): These values tell you the total battery power needed to achieve your desired runtime. If you're replacing batteries or building a custom battery bank, these figures are crucial. Remember that battery capacity degrades over time, so consider a slightly higher initial capacity.
Important Considerations When Choosing a UPS:
- Type of UPS:
- Standby (Offline): Most basic and affordable. Switches to battery power when mains fail.
- Line-Interactive: More advanced, offers voltage regulation (AVR) to correct minor power fluctuations without switching to battery.
- Online (Double Conversion): Provides the highest level of protection. Converts incoming AC to DC to charge batteries, then converts DC back to AC for the load, providing a constant, clean power supply. Best for critical applications.
- Output Waveform: For sensitive electronics, a "Pure Sine Wave" output is highly recommended. "Simulated Sine Wave" or "Stepped Approximated Sine Wave" UPS units are cheaper but can cause issues with some power supplies (especially Active PFC power supplies).
- Number of Outlets: Ensure the UPS has enough outlets for all your devices.
- Software and Connectivity: Many UPS units come with software that allows for automatic, graceful shutdowns of connected computers via USB or network connections.
- Battery Life and Replaceability: UPS batteries typically last 3-5 years. Check if the batteries are user-replaceable.
By using this calculator and understanding these factors, you can make an informed decision to select the right UPS to protect your valuable equipment and data.