First you will need to get an ISO image for the Windows 7 version you wish to install. You can either download the ISO directly from Microsoft or other online retailers or create the image from an original Windows 7 DVD. If you have an image you can skip to the next step, but if you have a DVD you can check out our ISO image creation guide linked below.
Related: How to Create an ISO image from a CD, DVD or BD
Now that you have the ISO image for Windows 7, you need to download the Windows 7 USB/DVD Download Tool from Microsoft. This tool will format the flash drive you wish to use and then correctly copy the contents of the ISO file onto the flash drive for use. Once downloaded, run the file to complete the installation process.
Run the tool after installation and click the ISO File option before browsing through your computer to locate the ISO file you wish to copy. Click on ‘Open’ after selecting the intended file and you will be returned back to the tool’s main screen.
Now from the Choose media type screen you can select USB device. If you wish to copy Windows 7 installation files onto an external hard drive, you have the option to select that as well. If the USB flash drive you want to use is not plugged into the computer, do it now and click on the refresh button to make it appear in the tool.
Click the ‘Begin Copying’ button now and if your flash drive is not already empty, you will be prompted with an ‘Erase USB Device’ option. The tool will now format the flash drive and you will see the ‘Creating Bootable USB device’ message. Once the USB is ready, you will receive the completion notification and can use the flash drive to install Windows 7 on devices without optical drives.