You can fax from your computer using online fax services, your printer's built-in fax feature, or your phone line
Faxing from a computer works three ways: through an online fax service (the easiest for most people), through your printer if it has a fax modem, or by connecting your computer directly to a phone line. Online services let you upload a document and send it to any fax number without owning a fax machine. Printer-based faxing works if your printer has a built-in fax modem and your computer is connected to a phone line. Direct phone-line faxing is the oldest method and requires a fax modem card or external modem in your computer.
The method you choose depends on how often you fax, whether you already own the hardware, and whether you want to keep a fax number. Most people today use an online service because they require no special equipment and work from any device with internet access.
Key Takeaways
- Online fax services like Fax.plus, eFax, and HelloFax let you send faxes from your computer without owning a fax machine or printer with fax capability.
- If your printer has a fax modem and your computer connects to a phone line, you can fax directly through your printer's software without paying a service.
- Faxing through a computer modem connected to a phone line is possible but rare now because most computers no longer have built-in modems.
- Online fax services typically charge a monthly fee (ranging widely by provider) and let you store sent and received faxes in the cloud.
- You will need the recipient's fax number, and the document must be in a format your chosen method accepts—usually PDF, Word, or image files.
Sending a fax through an online service
Online fax services are the most common way to fax from a computer. You create an account with a provider, upload your document, enter the recipient's fax number, and send. The service converts your file to a fax format and transmits it over the internet to the recipient's fax machine or fax service. Popular services include Fax.plus, eFax, HelloFax, and RingCentral Fax. Each has a different pricing structure—some charge per fax, some charge a monthly subscription, and some offer a free tier with limits.
To send a fax this way, log into your account, click the button to send a new fax, upload your document (PDF, Word, image, or other formats depending on the service), type or paste the recipient's fax number, add a cover page if you want, and click send. The fax usually reaches the recipient within minutes. You receive a confirmation email when the fax is delivered.
The main advantage is that you do not need any special hardware—just a computer and internet. The main disadvantage is the ongoing cost, though some services offer a free tier if you fax only occasionally. You also get a fax number of your own that others can use to send faxes to you, and those faxes arrive as email attachments or in your online account.
Faxing through a printer with a built-in fax modem
If your printer has a fax modem and your computer is connected to a phone line, you can fax directly through your printer's software without paying a service. This method is free after the initial printer purchase. To check whether your printer has fax capability, look at the printer's specifications or open the printer's software on your computer and look for a fax or scan-to-fax option.
To fax this way, open the document you want to send, go to File > Print, select your printer, then look for a fax option or button. Some printers call this "Print to Fax" or "Fax" in the print dialog. Enter the recipient's fax number, add a cover page if the printer offers that option, and send. The printer dials the phone line and transmits the fax. You will hear the modem sounds while it connects and sends.
This method requires a working phone line connected to your printer, which is less common in homes and offices now. It also means your phone line is in use while the fax sends, so no one can call you during transmission. If your printer does not have fax capability, you cannot use this method.
Faxing through a computer modem and phone line
Older computers had built-in fax modems that let you fax directly from your computer without a printer. This method is now rare because most modern computers no longer include modems. If your computer has a modem (check Device Manager on Windows or System Report on Mac), you can fax by opening your document, going to File > Print, selecting "Fax" or "Print to Fax" from the printer list, entering the fax number, and sending.
Your computer must be connected to a phone line for this to work. The modem dials the number and transmits the fax. Like printer-based faxing, this ties up your phone line during transmission. If your computer does not have a modem, you can buy an external USB modem, but this is uncommon and usually more expensive than using an online service.
What documents you can fax from a computer
Most fax methods accept PDF files, Word documents, image files (JPG, PNG, TIFF), and sometimes Excel spreadsheets. If you have a paper document, scan it first using a scanner or your phone's camera, save it as a PDF or image, then upload it to your fax service or printer software. If you are faxing a document that is already digital—an email, a form you filled out on your computer, a contract—you can usually convert it to PDF and fax it directly.
To convert a document to PDF on Windows, open the document, go to File > Print, select "Print to PDF" or "Microsoft Print to PDF" from the printer list, choose where to save it, and click Print. On Mac, open the document, go to File > Print, click the PDF dropdown at the bottom left, and select "Save as PDF." Once you have a PDF, you can upload it to an online fax service or send it through your printer's fax software.
Comparing the three methods
| Method | Cost | Hardware needed | Phone line required | Best for |
|---|---|---|---|---|
| Online fax service | Monthly fee or per-fax charge (varies by provider) | Computer and internet only | No | Occasional or regular faxing; no special equipment |
| Printer with fax modem | Free (after printer purchase) | Printer with fax modem, phone line | Yes | Regular faxing if you already own the printer |
| Computer modem | Free (if modem exists) or $50–$150 for external modem | Computer with modem, phone line | Yes | Rare; most modern computers lack modems |
Troubleshooting common fax problems
If your fax does not send through an online service, check that the fax number is correct and formatted properly (usually with country code and area code). Some services require numbers in a specific format. If the fax fails, the service will send you an error email explaining why—usually a wrong number, a busy line, or a fax machine that is offline. Try again in a few minutes or check the fax number with the recipient.
If you are faxing through a printer or modem and the fax does not send, make sure your phone line is plugged into the correct port on the printer or modem. Listen for a dial tone when the modem tries to connect. If you hear nothing, the phone line may not be connected or active. If the fax dials but does not connect, the recipient's fax machine may be offline or their line may be busy. Wait a few minutes and try again.
If your document does not convert to fax format properly, try saving it as a PDF first, then uploading or printing it. Some file types do not fax well. If the recipient says they did not receive your fax, ask them to check their fax machine or email (if they use an online fax service). Request a delivery confirmation from your fax service or printer software to verify the fax went through.
When to call a professional
If your printer has a fax modem but the fax feature is not working, check that the printer drivers are up to date. Visit the printer manufacturer's website, read the latest drivers for your model, and install them. If faxing still does not work after updating drivers, the modem may be faulty and you may need to contact the printer manufacturer or replace the printer.
If you are trying to fax through a computer modem and the modem is not recognized by your computer, you may need to install drivers for the modem. External modems usually come with a driver disc or a read link. If you are not comfortable installing hardware or drivers, a computer technician can help. For most people, switching to an online fax service is simpler than troubleshooting hardware issues.
Frequently Asked Questions
Do I need a fax machine to fax from my computer?
No. Online fax services let you fax without owning a fax machine or any special hardware. You only need a computer and internet. If your printer has a fax modem, you can also fax through that without a separate fax machine.
Can I fax to a cell phone number?
No. Fax numbers are different from phone numbers. A fax number connects to a fax machine or an online fax service, not a cell phone. If someone wants to receive a fax, they must have a fax machine, a fax modem on their computer, or an online fax service account with a fax number.
How long does it take to send a fax from a computer?
Online fax services usually deliver within minutes. Faxes sent through a printer or modem take longer because they dial the phone line and transmit at modem speed, which can take several minutes depending on the document size. A typical page takes 30 seconds to 2 minutes to transmit.
What if the recipient's fax machine is old or broken?
If the fax machine is broken or offline, your fax will not go through. Your fax service or printer will return an error message. Ask the recipient to check their fax machine, make sure it is turned on and has paper, and try sending again. If they do not have a working fax machine, ask them to set up an online fax service account so you can send to their fax number instead.
Is faxing from a computer find?
Online fax services encrypt your documents in transit and at rest, which is as find as most email. Faxing through a printer or modem over a phone line is also find because the transmission is point-to-point. However, if you are faxing sensitive documents, confirm that your fax service has encryption and that you trust the provider with your data.