7 Website Errors That Show Up on Mobile but Not on Your Computer

You opened your website on your phone yesterday, and something felt off. A button was in the wrong place. Text looked squashed. An image didn’t load quite right. So you opened the same page on your laptop and everything looked fine. You felt confused, then a little worried, then you just closed the browser and moved on with your day.

This happens to a lot of business owners I talk to, and it’s one of the most frustrating parts of having a website in 2024. You can’t see the problem from the device you use for design and testing. But your potential clients? They’re seeing it on their phones. And they’re making decisions about whether to work with you based on what they see there.

Here’s the thing, though: this isn’t your fault, and it’s absolutely fixable. Mobile and desktop websites are completely different animals. They follow different rules. Different things can go wrong on each one. Once you know what to look for, you can spot these issues yourself, and if you can’t fix them, you’ll at least know exactly what to tell your web designer.

Let me walk you through the seven mistakes I see most often that look perfect on a computer but break down on a phone. Some of these are technical. Some are just about how content behaves when it shrinks down to 390 pixels wide. All of them are opportunities to make sure your website works for everyone who visits it, not just the people viewing it on a big screen.

1. Images That Are Too Wide for the Screen

This is the most common one I see, and it’s usually an easy fix. You upload an image that’s 1200 pixels wide because it looks gorgeous on your desktop. On your laptop, it scales down beautifully. On a phone, something different happens: either the image gets cut off at the edges, or the phone stretches it to fit, which makes it blurry and weird.

The problem is that a phone screen is typically between 375 and 430 pixels wide. That 1200-pixel image has to squeeze down to something that small. If your website isn’t designed to handle that squeeze, you get visual chaos.

What you’re looking for on your phone: images that look crisp and clear, not blurry or cut off. If you see an image that seems stretched or distorted when you view it on mobile, that’s your signal. Take a screenshot and send it to your web designer along with a note about which page it’s on and what the image is supposed to show. They can adjust how the image displays on mobile without changing the desktop version at all.

This is one of those opportunities where mobile testing actually helps your desktop experience too. Optimizing images for mobile often makes your whole website load faster.

2. Text That’s Too Small to Read

On your laptop, you set your body text to 14 pixels because it looks elegant and spacious. It reads fine when you’re sitting three feet from the screen. On a phone held four inches from your face, that same 14-pixel text becomes a strain. People have to zoom in to read it, and then they get frustrated and leave.

This is where I see a lot of women holding back from promoting themselves, actually. They worry that their website text is hard to read because people keep asking them to repeat themselves or saying, “I couldn’t quite see what you wrote.” That’s usually this problem right here.

Mobile text should be at least 16 pixels. I know that sounds big when you look at it on your computer, but on a phone, it’s just right. Headlines can be proportionally larger, and your smallest text (like disclaimers or fine print) can be 12 pixels in a pinch, but your main content? 16 pixels minimum. That’s the golden rule.

Here’s what to do: Open your website on your phone without zooming in. Try to read your main content. If you have to pinch to zoom to read it comfortably, something needs adjusting. That’s your opportunity right there.

3. Buttons That Are Too Small or Too Close Together

You designed a beautiful navigation menu with five buttons across the top. On your desktop, they’re perfectly spaced. Elegant. Professional. On a phone, they’re either crammed together so tightly that your thumb hits three buttons at once, or they’re so small you have to tap three times to hit the right one.

Mobile fingers and desktop mice are completely different creatures. A finger is about a quarter-inch wide. A mouse cursor is basically a point. Your buttons need to be big enough and far enough apart that someone can tap the right one without accidentally hitting the button next to it.

The standard guideline is 44 by 44 pixels minimum for any button on mobile. That’s larger than it looks on your desktop, but it’s exactly what feels right when you’re holding a phone. If your buttons are smaller than that or clustered too tightly, that’s an opportunity to improve the whole experience of your site.

What to test: Open your website on your phone and try to tap every button or link. Can you hit what you’re aiming for on the first try? If you’re overshooting or undershooting, let your designer know. This is a quick fix in most cases.

4. Forms That Take Over the Entire Screen

You have a contact form or a sign-up form somewhere on your site. It looks clean on your desktop. On mobile, the form field takes up the entire screen. The label above it is barely visible. There’s no context for what you’re actually asking for. And when the keyboard pops up, the form pushes up out of view.

This one frustrates people faster than almost anything else. Someone wants to contact you, they pull out their phone, and the form experience is so clunky that they just close the browser instead. You lose a potential conversation.

What you’re looking for: Open your website on your phone and find your form. Does it feel easy to fill out? Can you see the full form on the screen at once? When you tap into a field and the keyboard appears, does the form stay in view? If the answer is no to any of these, that’s your opportunity.

Some forms are better designed as multiple pages on mobile, showing one or two fields at a time instead of a wall of inputs. Some just need better spacing and sizing. Either way, this is a conversation worth having with your designer.

5. Horizontal Scrolling or Content That Extends Beyond the Screen Width

You can scroll up and down on your phone, but you shouldn’t need to scroll left and right. When horizontal scrolling shows up, it means something is wider than the phone screen can display. It’s usually a table, a code block, or sometimes an image that didn’t get optimized properly.

The feeling when you encounter this is immediate annoyance. You have to turn your phone sideways, or pinch and zoom, or scroll side to side to see the content. People don’t do that. They leave.

What to look for: Visit every page of your website on your phone and scroll down slowly. If you ever have to scroll horizontally to see content, you’ve found an opportunity. Take a screenshot and note which page it’s on and what’s causing the horizontal scroll. Usually, it’s something that needs to be redesigned for mobile viewing.

This is especially important if you have pricing tables, portfolio grids, or any kind of data visualization on your site. They might look gorgeous on desktop but cause horizontal scrolling nightmares on phone.

6. Navigation That Hides or Disappears

You have a beautiful desktop navigation menu. On mobile, it either collapses into a hamburger menu (three horizontal lines), or it disappears entirely. Sometimes, the hamburger menu is hidden in a place where people can’t easily find it. Sometimes, when they tap it, the menu doesn’t work at all.

This is a big one for confusing your mobile visitors. They can’t see how to get around your site. They can’t figure out where to find your services, or your about page, or your contact information. So they assume you don’t have what they’re looking for and they leave.

What to check: Open your website on your phone. Look for the navigation menu. Can you find it easily? When you tap it (whether it’s a hamburger menu or visible buttons), does it work? Can you click through to different pages? If the answer is no, or if it’s confusing, that’s your signal to talk to your designer about improving mobile navigation.

The good news is that there are now excellent mobile navigation patterns that are easy to use and don’t require complicated menus or nested dropdowns. Your designer can usually implement these without any technical heavy lifting on your end.

7. Slow Loading on Mobile Networks

This one isn’t visual like the others. You won’t see it when you open your website on your home WiFi. But when you open it on your phone using cellular data, it takes forever to load. The images pop in one by one. The text appears, then the images, then the buttons. Every element loads separately, one after another.

Your potential clients experience this all the time. They’re in their car, they’re at a coffee shop, they’re checking their email while they’re waiting for an appointment. They click on your link, and your website takes 15 seconds to load. By the time it’s ready, they’ve already moved on to someone else.

This usually happens because images are too large, there’s too much code, or the server isn’t optimized for speed. On your home computer with a fast internet connection, you never notice. But mobile networks are slower, and mobile devices have less processing power. Your website needs to be lean and fast.

What to test: Open your website on your phone using mobile data, not WiFi. Notice how fast it loads. Are you waiting for elements to appear? Does it feel slow? If you’re waiting more than a few seconds for the full page to load, that’s an opportunity to optimize. Your designer can compress images, clean up code, and make other adjustments that make a huge difference on mobile networks.

This one has a bonus benefit: a faster website is better for everyone, including Google. Speed matters for search rankings too.

How to Check Your Website on Mobile (Without Getting Frustrated)

Before you start looking for these issues, you need a good way to view your website on an actual phone. You can use Chrome’s responsive design tool (right-click on your website, click “Inspect,” then click the device icon), but it’s not the same as viewing on a real phone. The best approach is to actually open your website on your phone.

Use your phone’s browser to visit your website. Scroll through every page. Test every form. Click every button. Look for things that feel off or broken. This usually takes 15 minutes, and it’s absolutely worth your time.

Write down anything you find that doesn’t work right. Take screenshots if you can. Note which page the issue is on and what exactly isn’t working. When you send this to your designer, you’re not saying, “Something looks wrong.” You’re saying, “On the mobile version of my contact page, the form fields are too small and I have to tap multiple times to hit the right one.” See the difference? That’s the information they need to help you.

The Real Opportunity Here

I want to circle back to something I mentioned at the beginning. A lot of women hold back from sharing their websites and promoting their businesses because something feels off. They can’t quite put their finger on it. They open it on their phone and think, “Yeah, something’s not right here.” But when they look on their laptop, it seems fine.

That discrepancy? That’s driving a wedge between you and your own confidence in your site. You’re not wrong about something being off. Your phone is telling you the truth. The opportunity isn’t to ignore that feeling. It’s to figure out exactly what needs adjusting and then fix it.

Once your website works beautifully on mobile and desktop, that hesitation goes away. You feel confident sharing it. You’re not embarrassed anymore. And here’s the thing: your potential clients are seeing a website that actually works, which means they can focus on whether they want to work with you, not on whether they can navigate your site.

That’s when the magic happens. That’s when your website finally feels like it’s on your side, not working against you.

Frequently Asked Questions

How do I know if my website has mobile problems?

Open it on your phone and spend five minutes scrolling through each page. Can you read the text comfortably without zooming? Can you tap buttons without hitting the wrong one? Does everything load quickly? If the answer is yes to all three, you’re probably fine. If it’s no to any of them, you’ve found an opportunity.

Can I fix these issues myself, or do I need to hire someone?

It depends on the issue and how comfortable you are with technology. Image sizing and basic CSS adjustments are sometimes doable in WordPress or other website builders. Form layouts, navigation problems, and loading speed usually need a designer’s touch. Start by identifying exactly what’s broken, and then decide whether it’s a DIY fix or a conversation with your designer.

Will my website automatically look good on mobile if I use a website builder like WordPress or Squarespace?

Most modern website builders have responsive design built in, which means your site should adapt to mobile screens automatically. But that doesn’t mean it’s optimized for mobile. You still need to test it on an actual phone and make sure buttons are clickable, text is readable, images load well, and forms are easy to fill out.

Should I focus on desktop or mobile first when designing my website?

I always recommend designing for mobile first, then enhancing for desktop. That way, you make sure the core experience works on the device most of your visitors are using. But honestly, your website should work beautifully on both. You shouldn’t have to choose.

If your website no longer feels like you, let’s talk about it – Book a Free Website Clarity Call with Beth →