Most people know their site is tired long before they can explain why. The instinct is usually right, but the reasoning is usually wrong: they describe how it looks, when the real signs your website needs a redesign are almost always about how it works.
Here are the ones worth acting on, and the ones that only need a smaller fix.

It breaks on a phone
This is the clearest signal of all, because that is where most of your visitors are. Not a slightly cramped layout, but text that requires pinching, buttons too small to tap accurately, a menu that will not open, or a form that pushes the submit button off screen.
Sites built before responsive design became standard often technically display on a phone while being unusable on one. If you have never opened your own site on your own phone and tried to complete an enquiry, do that before reading further. It is the fastest diagnostic available.
Visitors arrive and nothing happens
Traffic without enquiries is one of the most common signs your website needs a redesign, and one of the most misdiagnosed. People assume they need more visitors when the visitors they already have are leaving without acting.
Usually the cause is structural. The page never says plainly what the business does. There is no obvious next step. The contact route is buried three clicks deep. The copy talks about the company rather than answering what the reader came to find out.
This is worth investigating properly before committing to anything, because occasionally it is one page that needs rewriting rather than a whole site that needs rebuilding.
Nobody can update it
If changing a price means emailing a developer who may or may not reply, the site will slowly drift out of date. Not because anyone is careless, but because friction wins. Opening hours stay wrong through a holiday. A service you stopped offering is still listed. Staff who left two years ago are still on the team page.
A site the business cannot edit is a site that gets worse every month by default, and no amount of styling fixes that.

It loads slowly
Slow sites lose visitors before the design is ever seen, and search engines factor loading speed into rankings. The usual culprits are accumulated plugins nobody remembers installing, images uploaded at full camera resolution, and a theme carrying features the site does not use.
Worth noting: slowness alone is not always one of the signs your website needs a redesign. Sometimes it is a maintenance problem rather than a design one, and a care plan or a cleanup fixes it for a fraction of the cost.
It describes a business that no longer exists
Businesses change faster than their websites. Services get added and dropped. The ideal customer shifts. Prices move. A site built for what the business was five years ago will actively work against what it is now, attracting the wrong enquiries and failing to mention the work you most want.
If you find yourself explaining to prospects that the website is out of date, that is not a small problem. That is the site doing damage.
You avoid sending people to it
A perfectly valid signal on its own. If you would rather send a PDF, a WhatsApp message or an Instagram profile than your own website, the site is not doing the job it exists for. Trust your own reluctance here, because prospects who arrive without you steering them will form the same impression and you will never hear about it.
What is not a good reason
Two things get mistaken for signs your website needs a redesign when they are not.
Boredom. You look at your own site far more than any customer does. Being tired of it is not evidence that it has stopped working. If enquiries are steady and the structure is sound, a colour and typography refresh is a much cheaper answer than a rebuild.
A competitor launched something. Their new site may be beautiful and converting badly. You have no way of knowing. Rebuilding in response to what a competitor looks like, rather than what your own site is failing to do, is how money gets spent on the wrong problem.

Redesign, refresh or rebuild?
These are three different jobs at three different prices, and knowing which you need is most of the decision.
A refresh keeps the structure and updates the surface: colours, type, images, some copy. Right when the site works but looks dated.
A redesign keeps the content and rankings you have earned and rebuilds the structure, layouts and conversion paths around them. Right when the foundations are sound but the site is not performing. This is what most people actually need, and it is the middle option in both cost and risk. It is also the one that protects existing search visibility, provided the redirect mapping is handled properly.
A rebuild starts again. Right when the platform itself is the obstacle, when there is almost no content worth keeping, or when the business has changed so completely that the old structure has no relationship to the new one. That is a new build rather than a redesign, and it should be priced as one.
Before you commit to anything
Do three things first. Open the site on your own phone and try to complete an enquiry. Check whether you have any analytics installed, because without a baseline you will never know whether the new site performed better. And write down what specifically is not working, in terms of what visitors do rather than how the site looks.
That last list is the actual brief. A designer who is given it will build something that fixes the problem. A designer who is only told to make it modern will make it modern.
If you are weighing this up, it may also help to understand what actually moves the price of a website, or to send the URL for an honest read on whether a redesign or a smaller fix is the right call.

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