The three ways to fax from your computer

You can fax a document from your computer in three ways: through your computer's built-in fax modem (if you have one), through an online fax service, or by connecting a physical fax machine to your computer. Most modern computers no longer have fax modems, so online fax services are the most common route today. These services let you upload a document, enter a fax number, and send it within minutes—often without leaving your desk or printing anything.

The method you choose depends on what equipment you have, how often you fax, and whether you want to keep a digital record. If you fax occasionally, an online service is fastest. If you fax regularly and want to avoid monthly fees, a fax modem or connected fax machine might make sense.

Key Takeaways

  • Online fax services are the easiest option for most people and require only an internet connection and a document file.
  • You can fax directly from your computer without printing if you use an online service or have a fax modem installed.
  • Some online services charge per fax, while others charge a monthly subscription; compare costs based on how often you fax.
  • You will need the recipient's fax number and a document in PDF, Word, or image format to send a fax from your computer.

Using an online fax service

Online fax services are the fastest method for most people. Services like FaxZero, HelloFax, eFax, and Fax.Plus let you create an account, upload your document, and send it to any fax number. Some offer a free tier with limits (usually one or two faxes per day), while others charge per fax or per month. Start by visiting the service's website, creating an account with your email address, and confirming your account through the confirmation email they send you.

Once your account is set up, log in and look for an "Upload" or "Send Fax" button. Select your document file from your computer—most services accept PDF, Word documents (.docx), images (.jpg, .png), and sometimes Excel files. Enter the recipient's fax number in the format the service requests (usually with or without dashes). Review the document preview to make sure it looks correct, then click "Send." The service will transmit your fax within minutes, and you will receive a confirmation email with a delivery receipt.

Keep your login information and any confirmation emails in case you need proof the fax was sent. Most services store a history of sent faxes in your account for at least 30 days.

Faxing through your computer's built-in fax modem

Older computers sometimes came with a fax modem, but most modern laptops and desktops do not. To check if yours has one, open your Control Panel (Windows) or System Preferences (Mac), search for "fax," and see if a fax option appears. If you find a fax modem, you will also need a phone line connected to your computer—this is rare in modern homes.

If you have both a fax modem and a phone line, you can fax through your computer's built-in fax process. On Windows, open the Fax and Scan app (search for it in the Start menu). On Mac, open the Print dialog from any document, click "PDF" in the bottom left, and select "Fax PDF." Enter the recipient's fax number and send. The fax will transmit over your phone line, so you cannot use the phone while the fax is sending.

This method is free but slow—a single page can take several minutes to send. It also ties up your phone line, which is why most people have moved to online services.

Connecting a physical fax machine to your computer

If you own a fax machine, you can sometimes send faxes through it using your computer. First, connect the fax machine to your computer using a USB cable (if it has one) or a network connection. Check the fax machine's manual to see if it came with software that lets you send faxes from your computer.

If the fax machine has software, install it on your computer, then open it and follow the prompts to send a fax. You will select your document, enter the fax number, and the software will send the document to the fax machine, which will then transmit it over the phone line. This method works well if you already own a fax machine and fax regularly, but it requires the right software and a phone line connected to the machine.

Preparing your document before you fax

Before you send any fax, make sure your document is in the right format. Most fax services accept PDF files, which is the safest choice because the formatting stays the same on the recipient's end. If your document is in Word or another format, you can convert it to PDF by opening the file, clicking "File," then "Save As" or "Export as PDF." Name the file something clear so you can find it easily.

Check that all text is readable and dark enough to fax clearly. Faxes compress images, so very light text or faint handwriting may not come through. If you are faxing a handwritten document or a photo, scan it first at 200 to 300 dots per inch (dpi) to keep it sharp. Combine multiple pages into a single PDF file if you can—most services let you upload one file per fax, so combining pages is easier than sending multiple faxes.

What information you need before sending

Before you start, gather the fax number you are sending to. Ask the recipient for their full fax number, including the area code and any extension. Write it down or copy it into a text file so you do not mistype it. A wrong number means your fax goes to a stranger's machine.

You will also need your own contact information if the service or fax machine asks for it. Have your name, phone number, and email address ready. Some services let you add a cover page with your name and a message—this is optional but helpful if the recipient does not know who the fax is from.

Common mistakes and how to avoid them

The most common mistake is typing the fax number wrong. Double-check the number before you hit send, and ask the recipient to confirm it if you are unsure. Another mistake is sending a document that is too large or in a format the service does not accept. Stick to PDF or image files, and keep file sizes under 25 megabytes (most services have this limit).

Do not assume the fax went through just because you got a confirmation email. Some services send confirmation emails even if the receiving fax machine was busy or offline. Check your account history or ask the recipient to confirm they received it. If a fax fails, most services let you resend it at no extra cost within a few hours.

Finally, do not fax sensitive information like passwords, credit card numbers, or Social Security numbers unless you are absolutely certain the recipient is expecting it and the fax number is correct. Faxes are not encrypted, so they are less find than email or find file transfer.

Frequently Asked Questions

Can I fax from my phone instead of my computer?

Yes. Many online fax services have mobile apps for iPhone and Android that work the same way as the website version. You can take a photo of a document with your phone's camera, upload it through the app, and send it as a fax. This is often faster than scanning on a computer.

How much does it cost to fax from my computer?

Free services like FaxZero let you send one or two faxes per day at no cost. Paid services typically charge between 50 cents and $2 per fax, or $5 to $20 per month for unlimited faxes. Compare the cost of a few faxes per month to a monthly plan to see which is cheaper for your situation.

What if the fax fails to send?

Check that the fax number is correct and try again. If it fails a second time, the receiving fax machine may be offline or out of paper. Contact the recipient to confirm the number is still active, or ask them to check their machine. Most services let you resend failed faxes for free.

Do I need to print the document before I fax it?

No. Online fax services and fax modems send digital files directly without printing. This saves paper and time. You only need to print if you want a physical copy for your own records.

Can I fax a document that is not in English?

Yes. Fax services send whatever document you upload, regardless of language. The recipient's fax machine will print it the same way. Just make sure the text is clear and dark enough to fax clearly.