The general guidance is not to have your UPS run as long as possible. Your UPS should do one of two things. One option is to run your systems long enough to shut down. The other is to run them long enough for the generators to kick in. Expectations outside these two use cases are very expensive with diminishing returns. Answer from sidusnare on reddit.com
CyberPower
cyberpowersystems.com › tools › runtime calculator
Runtime Calculator | Power Runtime Calculating Tool
December 3, 2025 - As you move the cursor around the chart, a popup displays runtime estimates in minutes for each load by watts. Select the UPS model number you would like to view runtimes information on.
Call +18772976937
Address 4241 12th Ave E STE 400, 55379, Shakopee
Upscalc
upscalc.com › 1500va-ups-runtime-calculator
1500VA UPS Runtime Calculator - Estimate 1500VA UPS Backup Time | UPSCalc.com
Calculate the runtime of a 1500VA UPS system based on your equipment's power consumption. Estimate how long your UPS will last during a power outage.
UPS: What does "1500 VA" really mean?
VA or W is the measurement of the maximum rate of energy flow (power) that can be drawn from the system. It does not tell you the total amount of energy that can be stored in the system. You need WH for that. More on reddit.com
14
7
September 11, 2024What does 1500VA mean, and how do you calculate the load and back-up time that a 1500VA unit can provide? null
1 watt = 1 volt x 1 ampere Watt ... the UPS will provide enough power to maintain the equipment during power sags and also allows for an orderly shutdown over a 3-5 minute period. ... Sorry, there was a problem. Please try again later. Hello Max, 1500VA is the maximum amount of electricity that can be drawn from this unit. The amount of backup time is dependent on the amount of electricity that your equipment consumes. Here is a link to the product page showing the runtime ... More on bestbuy.com
4
October 13, 2018{UPS} APC UPS for Gaming, 1500VA Sinewave UPS Battery Backup with AVR and (3) USB Charging Ports, BGM1500, Back-UPS Pro Uninterruptible Power Supply {380-70=$310} [Amazon.ca]
The reviews for this unit are rather...concerning. More on reddit.com
15
0
May 18, 2022How do I determine UPS runtime? Most UPS specification pages don't list battery capacity (Ah) in the specs
The general guidance is not to have your UPS run as long as possible. Your UPS should do one of two things. One option is to run your systems long enough to shut down. The other is to run them long enough for the generators to kick in. Expectations outside these two use cases are very expensive with diminishing returns. More on reddit.com
33
25
August 1, 2022Videos
Reddit
reddit.com › r/homelab › how do i determine ups runtime? most ups specification pages don't list battery capacity (ah) in the specs
r/homelab on Reddit: How do I determine UPS runtime? Most UPS specification pages don't list battery capacity (Ah) in the specs
August 1, 2022 -
Am I missing something here? It seems like all UPS models are very clear about the VA, which I understand to be amount of power / watts the device can supply, but this doesn't give any indication of runtime. The Ah (ampere-hours) of the battery should reflect the amount of power stored in the battery, but it isn't even listed in many of models specification sheet.
I'm trying to buy a UPS to power my network rack for as long as possible. The wattage isn't huge, maybe 200 at peak load, but I'd like it to run as long as possible in an outage. Some brands have a "runtime calculator" for each product, but many don't. Is there an easier way to determine runtime? Or am I incorrect in my interpretation of the power units?
Thanks.
Top answer 1 of 11
33
The general guidance is not to have your UPS run as long as possible. Your UPS should do one of two things. One option is to run your systems long enough to shut down. The other is to run them long enough for the generators to kick in. Expectations outside these two use cases are very expensive with diminishing returns.
2 of 11
10
Setup your UPS, unplug it, start a timer.
Redway Battery
redway-tech.com › home › knowledge › how long does a 1500va ups battery backup last?
How Long Does a 1500VA UPS Battery Backup Last? | Redway Tech
October 25, 2024 - The runtime of a 1500VA UPS (Uninterruptible Power Supply) battery backup typically ranges from 10 minutes to 1 hour, depending on the load it supports. For example, if connected devices draw 300 watts, the UPS may last approximately 30 minutes. However, this duration can vary based on battery ...
Amazon
amazon.com › ask › questions › Tx12SALQLMC0R9R
Q: Does the 1500va indicate it's amp ...
1500VA is the maximum output (voltage x current) of the unit. At 1500VA the backup would last 216 VA/H/1550VA = .144 HR or 8 Minutes. ... I was able to run a 67 watt load (led tv) for 64 minutes before it quit. At the outset of the test it said 98 minutes of estimated runtime once the load ...
Upssize
upssize.com › 1500va-ups-runtime-calculator
1500VA UPS Runtime Calculator | 1500VA UPS Backup Time Estimator | UPSSize.com
Runtime increases significantly at lower loads. For example, using only 400W of a 1500VA UPS might yield 15+ minutes of runtime, depending on battery condition and temperature.
Backup Battery Power
backupbatterypower.com › pages › ups-run-time-calculator
UPS Run Time/Battery Backup Time Calculator – Battery Backup Power, Inc.
Manual/Generic Calculator: Calculate the estimated run time or battery backup time of any uninterruptible power supply (UPS) using the load in watts, the device load (in watts), number of batteries, battery voltage, and battery amp hours.
Reddit
reddit.com › r/homeowners › ups: what does "1500 va" really mean?
r/homeowners on Reddit: UPS: What does "1500 VA" really mean?
September 11, 2024 -
Here is from my research:
-
1500 VA = 1500 VA * 0.6 = 900 W
-
Router uses 5-20 W (according to Google)
-
Modem uses 6-35 W (according to Google)
-
How long does a Router+Modem last for 1500 VA?
-
900W / (20W + 35W) = 16.36 h
-
So I would assume a 1500 VA if only used on modem+router would last around 16 hours.
However, some random guy on Reddit said their modem+router only lasts 3.5 hrs:
https://www.reddit.com/r/batteries/comments/nvmrnn/the_best_ups_to_power_a_modem_and_router/
Google says 1500 VA runs router for 3 minutes.
So what's going on? How long does a 1500 VA actually last? What does 1500 VA actually mean?
Top answer 1 of 10
13
VA or W is the measurement of the maximum rate of energy flow (power) that can be drawn from the system. It does not tell you the total amount of energy that can be stored in the system. You need WH for that.
2 of 10
5
APC has a runtime tool on their website. Find a comparable sized APC ups and run the numbers
Amazon
amazon.com › APC-Battery-Protector-BackUPS-BX1500M › dp › B06VY6FXMM
Amazon.com: APC UPS Back-UPS Pro 1500VA UPS, 900W Battery Backup & Surge Protector, AVR, 10 Outlets (NEMA 5-15R), LCD, BX1500M Uninterruptible Power Supply for Computers, Wi-Fi Routers, Home Office Electronics : Electronics
1500VA / 900W RELIABLE BACKUP POWER: ... power interruptions · STAY CONNECTED WHEN IT MATTERS MOST: Provides up to 19 minutes of backup runtime at a 300W load—keeping computers, TVs, DVRs, Wi-Fi routers, modems, external drives, ...
APCGuard
apcguard.com › smart-ups-runtime-chart.asp
APC Smart-UPS Runtime Chart | APCGuard.com
APC Smart-UPS Runtime Chart for SUA Models.
Top answer 1 of 4
42
1500VA: VA = volt-ampere : VA in this case is an indicator of how much potential current the DC (Direct Current) batteries in the UPS are rated for. The load. Also the watt rating indicates the total AC (Alternating Current) amout that the UPS can convert and supply. The total drain of the devices added together. So how big is the gas tank? And how much gas can get out of the tank? Technically you could have 2 or 3 engines hooked up to the same gas tank, right? Just like you can have several devices plugged into the UPS drawing power during a power outage. So 1VA = 1Watt of DC power. The time the batteries run out of juice depends on how many things and how much power they are all pulling. You have to add up all the watts each device requires to function and don't exceed the watt rating of the UPS or your battery life will be shortened. The UPS also acts as a power conditioner keeping spikes and surges from blowing out delicate electronic circuits. I have 3 of these 1500va UPS devices and try to distribute the devices to not use over half of the watt ratings on each UPS. This has the effect of extending the life span of the batteries and you get more time before they go night night in the event of a power outage. The panel pn the ftont of these UPS does all the calculations for you.
2 of 4
5
1 watt = 1 volt x 1 ampere
Watt is a unit of WORK just like Horsepower is a unit of work
Volt is a unit of force
Ampere is 1 Coulomb of electrons (about 6 x 10 to the 18th power) flowing per second
Basically 1500VA is the same as 1500 Watts
If the power load is 1500 Watts or less, the UPS will provide enough power to maintain the equipment during power sags and also allows for an orderly shutdown over a 3-5 minute period.
CyberPower
cyberpowersystems.com › product output va › 1500 va
1500 VA UPS Products | CyberPower
Outlets: 12 - NEMA 5-15R View Runtime · View Details Check Prices · Showing 1–12 of 34 results · View all Product Selectors View all Tools and Calculators · UPS Product Selector › · Warranty Lookup Tool › · Sign Up · Transmitting ... Success! Thank you!
Call +18772976937
Address 4241 12th Ave E STE 400, 55379, Shakopee
Server Room Environments
serverroomenvironments.co.uk › 1500va-ups
1500VA UPS Price | 1500W UPS | 1.5kVA UPS | 1500VA | Server Room Environments
Some line interactive UPS offer ... measure. Battery runtime is load dependent. A typical 1500VA UPS an provide 3-9minutes runtime at full load....
Call +448000306838
Address St. Andrews Business Centre, Bromfield Industrial Estate, Queen's Lane, CH7 1XB, Mold
Upssystems
upssystems.co.uk › 1500va-ups
1500VA UPS (Uninterruptible Power Supply)
1500VA UPS (Uninterruptible Power Supply) (Uninterruptible Power Supply) UPS Type: Line-interactive · Format: Tower/Rack · Runtime: 5 Minutes · Manufacturer: Riello UPS · Full Specification · Buy Now · (Uninterruptible Power Supply) UPS Type: Line-Interactive ·
Eaton
tripplite.eaton.com › products catalog › ups battery backup › smart1500lcdxl
LCD 120V 1500VA 900W Line-Interactive UPS, AVR, Extended Runtime, 2U , LCD, USB, DB9, 8 Outlets | Eaton
Supports a half-load (450W) up to 12 min. during power outage Supports a full load (900W) up to 4.18 min. during power outage Features 8 protected 5-15R outlets Offers automatic voltage regulation (AVR) Extends runtime with optional BP24V15RT2U ...
Routerhax
routerhax.com › tools › ups-runtime-calculator
UPS Runtime Calculator - RouterHax
Add your network equipment (router, switch, modem) for the total load. A 1500VA UPS provides 15-30 minutes at 300-500W total load — enough for a graceful shutdown. For longer runtime, consider a 2200VA or 3000VA model.
EcoFlow
ecoflow.com › us › blog › calculate-ups-hours-and-extend-battery-life
How to Calculate UPS Hours and Extend Battery Life
January 29, 2026 - This guide shows you how to calculate UPS runtime hours and extend battery life when outages hit.
Lee Company
leecompany.com › home › how long does a ups battery last without power?
How Long Does a UPS Battery Last Without Power? | Lee Company
June 10, 2025 - If your UPS battery runtime isn’t what you thought it would be, these are the reasons why. The more equipment you connect, the faster the battery drains. That’s the tradeoff. A 1500VA unit running a single rack server might hold for 28 minutes.
Quora
quora.com › How-long-can-a-1500VA-900W-computer-UPS-able-to-power-a-25-watt-aquarium-heater-if-the-heater-is-on-100-of-the-time
How long can a 1500VA/900W computer UPS able to power a 25 watt aquarium heater if the heater is on 100% of the time? - Quora
In this UPS class, the battery varies in size from 8 a 16 AH@ 12 volts. It corresponds to about 12 volts * 8 AH = 96 watts. Some more expansive reach 12 Volts X 16 AH = 192 watts/h. Realistically, it is 80 to 160 watt...
APCGuard
apcguard.com › Smart-UPS-SC-Runtime-Chart.asp
APC Smart-UPS Entry Level Runtime Chart | APCGuard.com
Find out how long your APC Smart UPS SC will run based on the wattage and voltage. Call us today TOLL FREE 1-800-223-3574