How many watts does a fax machine use? Get your own answer: enter your wattage, hours of use per day and electricity rate, and press Calculate to see your cost per day, month and year. Those same results also cover fax machine power consumption. Also see how much electricity does a heat pump use.
If you are trying to work out how many watts does a fax machine use, the short answer is that it depends on what the device is doing: a thermal-paper fax sipping a few watts in standby behaves nothing like a laser model pulling several hundred watts for the minute it takes to print a page. This guide walks you through typical figures for each type of machine, the simple formula that turns watts into a yearly electricity bill, and the habits that keep the number low, so you can judge your own office or home setup with real arithmetic instead of a guess.
To understand wattage, start with what is a fax machine in electrical terms. A fax is a telephone-connected device that combines a scanner, a modem, a small computer and a printing engine in one cabinet. You feed a page in, the scanner reads it, the modem converts the image into signal tones, and the receiving fax machines at the other end reconstruct the page and print it. Because the machine must scan every outgoing sheet and decode every incoming one, it is more than a plain printer. Each of those parts draws power at different moments, which is why a single published figure never tells the whole story.
Three things change the draw more than anything else:
A facsimile (the original long name for the technology, also called telefax or telecopying, and sometimes a telecopier when the hardware is meant) was designed for offices that left it switched on all day, waiting for an incoming call. That always-ready design, shared by every facsimile unit from any brand, is the real reason standby watts are the main driver of fax machine energy use, as you will see in the worked example below.
The table lists typical ranges for each technology. They are ballpark figures taken from manufacturer specification sheets and rating labels, so treat them as a starting point and replace them with the numbers printed on your own device.
| Machine type | Standby (W) | Printing or receiving (W) | Typical daily active time |
|---|---|---|---|
| Thermal paper fax | 2 to 6 | 25 to 50 | 10 to 20 minutes |
| Inkjet fax | 3 to 8 | 30 to 60 | 15 to 25 minutes |
| Laser fax or multifunction | 4 to 10 | 350 to 600 | 20 to 40 minutes |
| Older office copier with fax | 20 to 100 | 600 to 1,200 | 30 to 60 minutes |
Notice that the spread between standby and printing is enormous, often a factor of fifty or more. A laser unit spends most of its life near its lowest figure and only briefly at its highest, which is why the average over a whole day lands somewhere surprisingly modest.
Published averages disagree because they mix different devices. Some energy sites quote a very low average wattage that reflects small thermal models, while business electricity comparison tables list a much wider range that includes laser and combined units. Both can be right for the machine they describe, because an average watt rating is only a guess at a typical unit. What you want is the figure for your own device, and you can find it in two places. You can also check how many watts does a cordless phone use.
First, look at the rating label on the back or underside of the machine. It usually shows voltage and either amps or watts. Second, check the user manual, which often lists separate numbers for standby, "sleep" and printing. If only amps are given, multiply by the supply voltage (120 V in most US outlets) to get the maximum wattage; the machine rarely reaches that maximum except for a moment while the fuser warms up.
A single incoming page passes through several stages, and the electricity demand changes at each:
Inkjet and thermal models skip the heavy fuser stage, which is the main reason their printing draw is a fraction of a laser fax. Thermal printing in particular heats a tiny strip rather than a drum, so it uses very little. On the other hand, thermal paper is more expensive and fades over time, so low wattage is not the only thing to weigh when you choose a model.
You do not need a special website to estimate your own bill. The method behind every online fax machine energy calculator is the same three-step sum, and you can run it with a pencil. First convert watts into energy over time, then convert to kilowatt-hours, then apply your electricity price.
The formula for daily energy use is:
$$E_{\text{day}} = \frac{(P_{\text{standby}} \times h_{\text{standby}}) + (P_{\text{active}} \times h_{\text{active}})}{1{,}000}$$
Here P is the power in watts, h is the number of hours in that mode, and dividing by 1,000 turns watt-hours into kilowatt-hours. Multiply the answer by your energy rate to get money:
$$\text{Bill} = E_{\text{day}} \times \text{days} \times \text{rate}$$
The energy rate is the price per kilowatt-hour printed on your utility statement. Do not just copy a national average: it varies a lot between states and between residential and commercial tariffs. Compare the average residential figure published for your state with the residential retail electricity rate on your own invoice, including delivery charges, and use the invoice, because it gives the most honest answer. Quoting the price per kWh also keeps the cost of different devices easy to compare.
Suppose you run a laser fax and multifunction device from a well-known brand that draws 6 W in standby and 420 W while printing. Over a typical day it prints for 0.4 hours (about 24 minutes in total across several received pages) and sits idle for the remaining 23.6 hours. Your utility charges $0.17 for each kilowatt-hour. These hours used per day are an estimate, so adjust them for your own habits and keep the same units throughout; the power used by the machine is what the formula multiplies.
Look closely at the split. Printing accounts for 168 Wh, but standby, at only 6 W, still contributes 141.6 Wh because it runs around the clock. Nearly half the electricity goes into waiting for a call that may never arrive. The same logic applies to every device that sits plugged in all day, and it is why switching a rarely used machine off at the wall can beat any efficiency feature on the box.
Running the same calculation for two lighter machines shows how much the technology matters. All rows assume the same $0.17 rate.
| Model | Standby | Active | Active hours per day | Per day (kWh) | Per year |
|---|---|---|---|---|---|
| Thermal fax | 4 W | 38 W | 0.3 | 0.106 | $6.59 |
| Inkjet fax | 5 W | 45 W | 0.35 | 0.134 | $8.31 |
| Laser fax | 6 W | 420 W | 0.4 | 0.310 | $19.21 |
Even the laser model has a running cost of less than a couple of coffees a year, so you should not rule out a fax purely for electricity reasons. The energy usage gap between technologies is real, but the dollar difference is small. The comparison matters most in an office that has several units, or when a heavy copier-fax is left on around the clock.
Knowing how does a fax machine work shows which parts actually draw watts. The machine can scan each outgoing sheet with a lamp and light sensor, and a scanned page becomes a bitmap that data compression shrinks before the modems turn it into tones for the phone lines. The receiving unit reverses the steps and prints. Of those stages, the scanner lamp and paper-feed motors draw a modest amount, and the print engine draws the most.
The transmission itself costs you almost nothing. Older analog systems and modern digital ones both ride on a copper line powered by the telephone network, and error correction happens inside the chip that is already running. A digital transmission over a clean line takes seconds, so the meaningful consumption sits in the local hardware: the scanner lamp, the motors that feed the paper tray, and the print engine.
Sending a fax uses the scanner and modem for a minute or less and prints nothing, so every outgoing transmission adds very little to your bill, and one digital transmission over a clean line takes only seconds. Receiving is where electricity use climbs, because the incoming page must be printed. If your machine prints every incoming page, including junk and marketing blasts such as fax broadcasting, the printing hours in the formula above grow. Storing received pages in memory and printing only the ones you need is a cheap way to cut active time.
Not to your electricity meter. The telephone line carries its own small current from the exchange, and a fax-over-internet service moves the signal through your router instead. If you connect the machine through a USB cable to a computer, you add the computer's draw only while it is awake and handling the job.
Business electricity comparison charts typically list equipment next to each other so you can see where the load really sits. In such lists, fax machines usually land near the bottom of the table when idle and in the middle when printing. A simple halogen light bulb can pull more than a thermal fax even while the fax is transmitting, and a laser printer burns far more than a fax during its warm-up.
The lesson from a usage comparison like this is that a fax is rarely the energy villain. The bigger budget items in a small business are heating and cooling, lighting and computers. Still, a fleet of ten old units left on 24 hours a day does add up, and the savings from a simple policy are free.
People often ask about the difference between fax machines and printers. A fax transmits and receives documents over a telephone line, while a printer simply produces pages from a computer. Electrically, a laser fax is close to a laser printer: the same fuser, the same toner cartridge and the same warm-up spike. An inkjet fax shares the low printing draw of an inkjet printer. So when you compare device wattage, pair like with like rather than a thermal fax against a laser printer.
Fax machines became ubiquitous in offices in the 1980s and 1990s, and email and the internet have since made most of them obsolete. Yet they remain in use in medical administration, law enforcement and legal work, where a signed paper page or an established secure channel still matters. A hospital that receives referrals by fax may keep several fax machines running continuously, and in that setting standby watts become the dominant term.
Because these sites need to receive a transmission at any hour, the machines are left on around the clock, so even a unit that uses PIN codes and encryption to protect stored pages still pulls its standby watts all night. If the power goes out the fax machine will not work, which is why some sites add a backup supply, and that supply adds to the load. For a small practice, a single low-power thermal or inkjet unit with a sleep mode can be the sensible compromise.
Fax machines with extras draw more than basic fax machines. Extras increase the wattage figure on the label. Be aware of these when you read a specification:
You can cut consumption without giving up the device. Start with the simplest levers and move toward the more involved ones.
To confirm where you stand, plug the machine into a plug-in power meter for a week and read the kilowatt-hours it logs. That measured figure replaces every assumption in the formula and settles the question of your actual consumption.
Supplies matter less than the plug, but they connect to watt-hours. Thermal models need special thermal paper, while laser and inkjet versions run on plain white paper, and a laser unit also needs fresh ink toner every few months. Fax machines in the same room share the supply burden, and using a lower-resolution mode for incoming pages shortens each print job, which trims printing time and your watt-hours too.
When you search for a number, three mistakes appear again and again: Also see docking station electricity consumption.
Keep those in mind and the published averages become useful guides rather than contradictions. A machine described as using a small average figure and another listed in a much higher business range may simply be different technologies measured under different assumptions.