Size and format first
Large photos straight from a phone can weigh several megabytes. Resize them to the size they will be displayed, plus a little extra for high-resolution screens, and compress them. Modern formats such as WebP or AVIF are usually much smaller than older ones with similar quality, and most current browsers support them.
Aim for each image to be as small as possible without visible damage. This improves load time, which matters for visitors on phones.
Alt text that serves people
Alt text is a short description of an image for those who cannot see it, including screen reader users, and it displays if the image fails to load. Write what the image shows and why it matters, in plain words: a technician replacing a water heater in a basement.
Skip the phrase image of. Keep it to a sentence or less. Do not stuff keywords. If an image is purely decorative, use empty alt text so screen readers skip it.
Filenames and captions
A filename such as water-heater-replacement.jpg is more useful than IMG_4021.jpg. It is a small hint to search engines and helpful to you when managing files. Use lowercase words separated by hyphens.
Captions are read more often than most body text. Use them when they add information, such as the location of a project type or the material used.
Loading and layout
Set width and height for each image so the page does not jump while loading. Use lazy loading for images below the visible area, but not for the main image at the top, which should load promptly. Ask your developer to serve different sizes for different screens.
Test a page on a mobile connection and look for slow images.
Real photos beat stock
Original photos of your team, work and premises show who you are and can appear in image search. Stock photos are everywhere and add little. If you must use stock, choose images that fit your actual work, and do not claim they show your staff.
Get permission before showing customers or their property, and avoid showing identifying details.
Avoid placing important text inside images. It cannot be read by search engines or screen readers, and it scales poorly on phones. Put phone numbers, prices and headings in real text.
If a graphic holds meaningful data, such as a chart, give it alt text or a nearby text summary.
A quick image routine
Before uploading any picture: crop it, resize it, compress it, rename it, then write the alt text. Keep a folder of finished originals so you do not repeat the work. Once a quarter, run a speed test on your busiest pages and replace the heaviest images first. This five-step habit takes a minute per image and keeps the site fast as it grows. Ask whoever edits your site to follow the same steps so quality does not depend on one person.
If your website platform generates several sizes of each image automatically, check that it also serves modern formats. Many builders offer this as a simple setting, and turning it on can shrink page weight without any extra editing work.
Common questions
Does alt text help rankings?
It helps search engines understand images and supports image search, but its main purpose is accessibility.
What image size should I upload?
Match the largest size the image is displayed at, with some allowance for sharp screens, then compress.
This guide is general information. Search engines change how they work and their guidelines; check Google's current documentation for your situation. Nobody can guarantee a ranking.