The basic way to fax from your computer
To fax a document from your computer, you need three things: the document itself (usually a PDF or image file), a fax service or modem that connects to a phone line, and the recipient's fax number. The actual steps depend on which method you choose — some are built into Windows or Mac, others use online services, and some require hardware you may already own.
The simplest route for most people is an online fax service. You upload your document to a website or app, enter the fax number, and the service sends it through the phone network on your behalf. You do not need a physical fax machine or even a landline. Services like eFax, Fax.plus, and HelloFax charge monthly or per-fax fees, though some offer a few free faxes each month to start.
If you have a fax modem (a piece of hardware inside or connected to your computer) and an active phone line, you can fax directly without paying a service. Windows and Mac both have built-in fax software, though you will need to set it up first. This route costs nothing per fax but requires the modem hardware and a phone line that is not in use while you fax.
Key Takeaways
- Online fax services are the easiest option for most people because they work on any computer and do not require a phone line or hardware.
- If you have a fax modem and a phone line, Windows and Mac both include free fax software that can send documents without paying per-fax fees.
- Faxing from your computer produces the same result as a physical fax machine — the recipient gets a copy on their end, whether they use a machine or software.
- Document format matters: PDFs and image files (JPG, PNG) work everywhere, but some services accept Word documents or scans directly from your computer.
Using an online fax service
Online fax services work like email for faxes. You create an account on their website, upload your document, type in the recipient's fax number, and click send. The service routes your document through the phone network and delivers it to the fax machine or fax software on the other end. The recipient sees a standard fax — they do not know it came from your computer instead of a machine.
Popular services include eFax (which also gives you a fax number to receive faxes), Fax.plus, HelloFax, and RingCentral Fax. Most charge between $10 and $30 per month for a set number of outgoing faxes, or you can pay per fax if you only need to send a few. Some offer a free tier with a limited number of faxes each month. The trade-off is convenience: you pay a small amount, but you avoid buying hardware and do not need a phone line.
To use one, sign up on their website, upload your PDF or image file, enter the fax number with the country code if it is international, add a cover page if you want, and submit. Most services send within minutes. You get a confirmation email when it goes through, and you can usually see a history of all faxes you have sent.
Faxing through Windows
Windows includes fax software called Windows Fax and Scan, but it only works if you have a fax modem connected to your computer and an active phone line. A fax modem is a hardware device (either built into older computers or connected via USB) that can dial a phone number and send data over the line, just like a fax machine does.
To check if you have a fax modem, go to Settings, search for "fax", and look for Windows Fax and Scan. If it appears, you likely have one. Open the app, click "New Fax", select your document, enter the recipient's fax number, and send. The software dials the number, transmits your document, and logs the result. This costs nothing per fax, but your phone line is tied up during transmission (usually 30 seconds to a few minutes depending on document size).
If you do not see Windows Fax and Scan or it says no modem is detected, you do not have a fax modem installed. In that case, an online service is your only option.
Faxing through Mac
Mac computers can fax through the print dialog if you have a fax modem and phone line set up. Open the document you want to fax (in Preview, Word, or any other app), click File, then Print. In the print dialog, look for a dropdown menu that says "Printer" and select "Fax [Your Modem Name]" instead. Enter the recipient's fax number and click Fax. The document sends through your modem the same way it would on Windows.
If you do not see a fax option in the print dialog, you either do not have a fax modem or it is not set up. Macs are less common with fax modems than they used to be, so most Mac users end up using an online service instead. The setup process for a modem on Mac is more involved than on Windows, so unless you already have one installed, an online service is simpler.
Preparing your document for faxing
Fax machines and fax software work best with PDFs and image files. If you have a Word document, Excel spreadsheet, or other file type, convert it to PDF first. On Windows, open the file, click File, then Print, and select "Print to PDF" or "Microsoft Print to PDF" from the printer dropdown. On Mac, open the file, click File, then Print, and click the PDF dropdown in the bottom left, then "Save as PDF".
If you are faxing a physical document (a signed letter, a contract, a check), scan it first using a scanner or your phone camera. Most phones have a built-in document scanner app, or you can use a free app like Adobe Scan or Microsoft Lens. Save the scan as a PDF or JPG image file, then upload it to your fax service or fax software.
Keep file size in mind: fax services and modems work faster with smaller files. A single-page PDF is usually under 1 MB and sends in seconds. A 20-page document with images might be 5 MB and take longer. If your file is very large, compress it or split it into smaller PDFs before sending.
What happens on the receiving end
When you fax a document from your computer, the recipient sees the same thing they would see from a physical fax machine. If they use a fax machine, it prints out a paper copy. If they use fax software or an online service, they receive it as a digital file in their email or account. The fax number you send to determines where it goes — a business fax number goes to their machine or their fax software, just like any other fax.
The recipient cannot tell whether your fax came from a computer or a machine. Faxes are faxes from their perspective. The only difference is on your end: you saved time by not walking to a machine, and you have a digital record of what you sent.
Cost comparison: online services vs. fax modems
| Method | Upfront Cost | Monthly Cost | Per-Fax Cost | Best For |
|---|---|---|---|---|
| Online fax service | None | $10–$30 (or free tier) | $0.50–$2 if pay-per-use | Occasional faxing, no hardware |
| Fax modem + phone line | $30–$100 (modem) | Phone line cost (if not already active) | None | Frequent faxing, already have a modem |
If you fax once or twice a month, an online service's free tier or a low monthly plan makes sense. If you fax multiple times a week, a fax modem pays for itself quickly. Most people today use online services because fax modems are becoming rare in new computers, and keeping a phone line active just for faxing is expensive.
Frequently Asked Questions
Can I fax to an email address instead of a fax number?
No, faxes go to fax numbers, not email addresses. However, some online fax services let you receive faxes at an email address they assign to you. If the person you are sending to has an email-to-fax service set up, you could email them instead, but that is their choice, not yours. Stick with the fax number they give you.
What if the fax number is busy or does not answer?
Online fax services automatically retry busy numbers a few times over several hours. Fax modems on Windows and Mac usually try once and report an error. If it fails, wait a few minutes and try again, or contact the recipient to make sure their fax machine is on and has paper.
Do I need to include a cover page?
No, but many people do. A cover page is a first sheet that says who the fax is from, who it is going to, how many pages follow, and sometimes a brief message. Most online fax services let you add one automatically. If you are using a fax modem, you can add a cover page manually by creating a document and faxing it first, then faxing the actual document after.
Is faxing from my computer find?
Faxing is less find than encrypted email because fax data travels over the phone network without encryption. If security matters (medical records, financial documents), ask the recipient whether they prefer email with password protection or a find file-sharing service instead. For routine documents, fax is fine, but it is not the most private option.
Can I fax internationally?
Yes, but it costs more. Online fax services charge extra for international faxes, usually $2 to $5 per page depending on the country. Fax modems can dial international numbers if your phone line supports it, but long-distance charges explore. For international documents, email or a file-sharing service is usually cheaper and faster.