You can fax from your computer using an online fax service, your printer's built-in fax feature, or fax software
Sending a fax from a computer works three ways: through an online fax service (the easiest for most people), through fax software installed on your machine, or through a printer that has fax capability built in. Online services let you upload a document and send it to any fax number without owning a fax machine. Fax software turns your computer into a fax modem if you have the right hardware. Printer-based faxing works only if your multifunction printer has a fax module and a phone line connected to it.
The method you choose depends on how often you fax, whether you need to receive faxes, and whether you already own the hardware. Most people find online fax services the simplest option because they require no special equipment beyond what you already have—a computer and internet connection.
Key Takeaways
- Online fax services let you send faxes from your computer to any fax number without owning a fax machine or printer with fax capability.
- Fax software requires a fax modem (a hardware card or external device) connected to your computer and a phone line, which most modern computers no longer have built in.
- Multifunction printers with fax modules can send faxes if they are connected to a working phone line, but they work best for occasional use.
- Online fax services typically charge a monthly subscription or a per-fax fee, while fax software and printer faxing use only your existing phone line costs.
Sending a fax through an online fax service
Online fax services are the most straightforward method for most computer users. Services like eFax, Fax.plus, and HelloFax let you create an account, upload a document (PDF, Word, or image), and send it to a fax number within minutes. You do not need any special hardware—just your computer and an internet connection.
To send a fax this way, sign up for an account on the service's website, choose a subscription plan (usually monthly), and verify your email address. Then open the "Send Fax" section, enter the recipient's fax number, upload your document, and click send. The service routes your document through their fax servers to the recipient's fax machine or fax service. Delivery typically takes a few minutes to an hour, depending on the service and time of day.
Most online services charge between $10 and $30 per month for a basic plan that includes a set number of outgoing faxes (often 50 to 100 per month). Some services charge per fax instead—usually 25 cents to $1 per page. If you need to receive faxes, the service assigns you a fax number and stores incoming faxes in your online account, which you can read or forward to your email.
Using fax software on your computer
Fax software turns your computer into a fax machine, but it requires hardware that most modern computers no longer include: a fax modem. A fax modem is either a card installed inside your computer or an external device connected via USB. It connects to a phone line and handles the actual fax transmission.
If you have a fax modem installed, open your fax software (Windows includes Fax and Scan; Mac users can use third-party software like eFax Messenger or Fax Utility), create a new fax, enter the recipient's fax number, attach or scan your document, and send. The software dials the number through your phone line and transmits the document. This method costs nothing beyond your regular phone line charges, but it is slow—a typical page takes 30 seconds to 2 minutes to send.
Finding a fax modem is the main barrier. Most laptops and desktop computers sold in the last 10 years do not include one. You can buy an external USB fax modem for $30 to $100, but you also need a phone line connected to it—not a cell phone line, but a landline or VoIP service with fax capability. This makes fax software practical only if you already have both the modem and a dedicated phone line.
Sending a fax from a multifunction printer
If you own a multifunction printer (also called an all-in-one printer) with fax capability, you can send faxes directly from the printer's control panel or from your computer using the printer's software. The printer must be connected to a working phone line—either a landline or a VoIP service that supports faxing.
To fax from the printer itself, place your document in the scanner tray or on the glass, press the Fax button on the printer's screen, enter the recipient's fax number using the keypad, and press Send. To fax from your computer, open the document you want to send, go to File > Print, select your printer from the list, look for a Fax option in the printer settings, enter the fax number, and click Print. The printer then scans the document and sends it through the phone line.
This method works well for occasional faxing if you already own the printer and have a phone line available. However, printer faxing is slower than online services and offers no way to receive faxes unless you sit at the printer waiting for them. It also ties up your phone line during transmission, so you cannot use the phone at the same time.
Comparing the three methods
| Method | Hardware needed | Speed | Cost | Best for |
|---|---|---|---|---|
| Online fax service | Computer and internet only | Minutes | $10–$30/month or per-fax fee | Frequent faxing, receiving faxes, no phone line available |
| Fax software | Fax modem and phone line | 30 seconds to 2 minutes per page | Phone line cost only | Occasional faxing, already have modem and phone line |
| Multifunction printer | Printer with fax module and phone line | 1–3 minutes per page | Phone line cost only | Occasional faxing, already own the printer |
Common mistakes to avoid when faxing from your computer
The most common error is entering the fax number incorrectly. Fax numbers look like phone numbers but are not interchangeable—a fax number goes to a fax machine or fax service, not a voice line. Double-check the number before sending, especially if you copied it from an email or website. If the fax fails, the service or software will usually tell you why (number not recognized, line busy, or no answer).
Another mistake is sending a document in the wrong format. Online fax services accept PDF, Word, and image files, but some older fax software only reads TIFF or PDF. If your document is in an unusual format, convert it to PDF first using your computer's print-to-PDF feature or a free tool like Smallpdf.
If you are using a multifunction printer, do not forget that the printer needs a phone line connected to its fax port—plugging the phone line into the printer's regular phone jack will not work if the printer has separate ports. Check your printer manual to find the correct port. Also, remember that faxing through a printer ties up your phone line, so incoming calls will not ring while a fax is sending.
Setting up a fax number to receive faxes
If you need to receive faxes on your computer, an online fax service is your only practical option. When you sign up, the service assigns you a fax number (usually a local or toll-free number in your area). Anyone can fax documents to that number, and they arrive in your online account as PDF files that you can read, view, or forward to your email.
Fax software and multifunction printers can receive faxes too, but they require a dedicated phone line and someone to be present at the computer or printer to answer the incoming fax. This is impractical for most people. Online services store your faxes indefinitely (or for a set period, depending on your plan) so you can access them anytime from any device.
Frequently Asked Questions
Can I fax from my smartphone or tablet?
Yes, most online fax services have mobile apps for iPhone, iPad, and Android. You can upload a photo or document and send it the same way you would from a computer. Some services let you take a photo of a paper document and send it as a fax directly from the app.
What if the fax fails to send?
Online services and fax software will show you an error message explaining why—usually "number not recognized," "line busy," or "no answer." Check that the fax number is correct and try again. If the problem persists, the recipient's fax machine may be offline or their line may be having trouble. Ask them to confirm their fax number or try again later.
Do I need a phone line to use an online fax service?
No. Online fax services send faxes through the internet, so you need only a computer and internet connection. You do not need a phone line at all. This is one reason they are popular—you can fax from anywhere without owning a fax machine or printer.
Can I fax a document that is already on my computer without scanning it?
Yes, with online fax services and fax software. If your document is already a PDF or image file, you can upload it directly. If it is a Word document or other format, most services accept it as-is. With a multifunction printer, you must either scan a paper copy or print the document to the printer's fax function, which scans it before sending.
How long does it take to receive a faxed document?
Online fax services usually deliver incoming faxes to your account within a few minutes of receipt. Email notifications can take a few minutes longer. Fax software and multifunction printers receive faxes in real time if they are powered on and connected to a phone line, but you must be present to answer the incoming call.