eSIM Unlimited Data Plan: Is It Truly Unlimited or Subject to a Fair Use Limit?

Short answer: No, “unlimited” eSIM plans are usually not unlimited in the way travellers assume.

In most cases, they include a hidden high-speed data cap, after which speeds are throttled so aggressively that the connection becomes barely usable.

As someone who works directly with mobile carriers and has personally used so-called “unlimited” eSIMs while travelling, I want to explain how this actually works, why confusion is so common, and how to tell the difference between marketing unlimited and true unlimited data.

TL;DR — Is “Unlimited” Data Truly Unlimited?

• Most “unlimited” eSIM plans are not truly unlimited, they include a hidden high-speed data cap.
• After this cap (often around 2–3GB per day), speeds are heavily throttled to levels that make maps, translation apps, and browsing difficult or unusable.
• These limits are not accidental or caused by congestion, providers choose them in advance because they pay carriers per GB used.
• Fair usage policies exist mainly to reduce provider costs and increase margins, not to protect networks.
• Many travellers never notice the issue because they use less than 1GB per day, which is why these plans persist.
• A genuinely unlimited eSIM plan has no fair usage policy, no speed tables, no daily caps, and allows unrestricted hotspot use.
• If an eSIM has a fair usage policy, it is not unlimited, by definition.

What “Unlimited” Really Means in the eSIM Industry

At the carrier and wholesale level, “unlimited” is not a fixed product.

When an eSIM provider negotiates with a carrier, they are typically given multiple configuration options, including:

• How many gigabytes of high-speed data a user gets
• What speed the connection is throttled to after that
• Whether hotspot usage is restricted
• Whether throttling resets daily or continues for the remainder of the plan

In other words, providers choose the limit.

The business incentive is simple:

• Providers pay carriers per gigabyte used
• Lower caps = lower wholesale costs
• Lower costs = higher margins

The disconnect happens because most customers reasonably interpret “unlimited” to mean unlimited usable data, not “2–3GB of fast data followed by 1990s-era speeds.”

My Personal Experience with Fair Usage Policy in Japan

I’ve personally used Holafly while travelling in Japan.

Each day, after roughly 2GB of usage, my data was throttled to around 300kbps.

At that speed:

• Google Maps would not load properly
• Translation apps struggled
• Websites and apps failed to open
• The connection was effectively unusable for normal travel needs

Support framed this as “still unlimited,” because technically the connection wasn’t cut off, but in practice, 300kbps is barely enough to send messages.

Japan’s abundance of public Wi-Fi saved me. Without it, the experience would have been genuinely stressful, especially when you’re navigating a foreign city expecting uninterrupted connectivity.

The Fair Usage Policy Myth

You’ll often hear explanations like:

• “Network congestion”
• “Temporary deprioritisation”
• “Carrier-controlled throttling”
• “High-usage periods”
  

In reality, these are distractions from the core truth:

The provider chose your data cap in advance.

Tourist eSIM users represent a tiny fraction of total network traffic. Watching a short video or hotspotting your laptop is not destabilising national infrastructure.

Fair usage policies exist primarily because:

• Providers pay for the data you use
• Throttling reduces their costs
• “Fair use” sounds more reasonable than “we capped you”

The policy isn’t reactive. It’s pre-configured.

Why Some Travellers Never Notice a Problem

Many people will say:

“I used an unlimited eSIM and it worked fine for me.”

That can be completely true.

Most travellers:

• Use under 1GB per day
• Rely on hotel Wi-Fi
• Don’t hotspot
• Don’t upload or stream heavily

If you never exceed the hidden cap, you’ll never see the throttling.

The problem isn’t that throttling always happens, it’s that you only discover it once you need the data most, despite paying for “unlimited.”

What Customers Ask Us After Being Burned Elsewhere

We regularly receive messages like:

“My last eSIM said unlimited, but every day my speed dropped so low I couldn’t load Google Maps. What’s your fair usage policy?”

Our answer is always the same:

• We don’t have one
• There is no upper limit on high-speed data
• Our highest recorded usage in a single day is 140GB

Another common question:

“Will hotspotting slow my speeds or trigger a cap?”

No. Hotspot data is treated exactly the same as on-device data, with no throttling or secondary limits.

The fact that customers feel the need to ask these questions at all shows how normalised fake ‘unlimited’ plans have become.

Why We Removed Fair Usage Entirely

When we first entered this industry, we trusted the “unlimited” label ourselves.

Only after a customer experienced throttling did we dig deeper into carrier documentation and realise what was actually happening. At that point, we made a decision:

If we couldn’t delete our fair usage policy entirely, we wouldn’t continue.

That meant:

• Renegotiating carrier agreements
• Accepting significantly lower margins
• Keeping prices the same instead of increasing them

From a purely financial perspective, fake unlimited plans are far more profitable.

From an ethical perspective, we couldn’t justify them.

Real-World Unlimited Usage Examples

Some real, anonymised examples from our customers:

• 140GB used in a single day, no throttling
• Business travel with 15GB+ hotspot usage per day
• A designer travelling through Europe uploading and downloading large files continuously, without interruption

These aren’t edge cases, they’re simply what happens when a plan is genuinely unlimited.

How to Tell If an “Unlimited” eSIM Is Actually Unlimited

Here’s the simplest rule:

If a provider has a fair usage policy, it is not unlimited.

True unlimited providers don’t need:

• Speed tables
• Throttling thresholds
• Asterisks
• PDFs explaining what happens after you use too much

Unlimited should mean:

• Unlimited high-speed data
• For the full duration of your plan
• Limited only by reception quality, not usage volume

Anything else is just careful wording.

Final Thought

Some travellers will never hit a hidden cap, and that’s why fake unlimited plans persist.

But if you’re paying for “unlimited,” you shouldn’t have to worry about:

• Watching your data usage
• Avoiding hotspotting
• Losing navigation mid-trip
• Suddenly being told 300kbps is “good enough”

Unlimited either means unlimited, or it doesn’t.

Frequently Asked Questions: eSIM Unlimited Data Plans

If you’ve ever wondered whether an eSIM unlimited data plan is truly unlimited or has a fair use limit, you’re not alone. A lot of travellers have been caught out by “unlimited” plans that slow down once you actually start using them. These questions break down what’s really going on, in plain English.

TD;DR: If an eSIM unlimited data plan has a fair usage policy, it isn’t truly unlimited high-speed data. Koala Sim’s unlimited plans have no fair usage policy, no daily caps, and no usage-based throttling.

Is an eSIM unlimited data plan actually unlimited?

Sometimes yes, often no.
Many eSIM plans advertised as “unlimited” include a fair usage policy that quietly limits how much high-speed data you can use. Once you pass that point, speeds can drop dramatically. Koala Sim’s unlimited plans work differently, there’s no fair usage policy, so your data stays high-speed for the entire plan duration (as long as you have coverage).

What does a fair usage policy really mean?

In simple terms, it means there’s a hidden limit.
You might get fast data at first, but after a certain amount of use, your speeds can be slowed to the point where maps, browsing, and uploads become frustrating. Koala Sim removes this entirely by offering unlimited plans with no fair usage policy and no speed caps.

What happens when you hit a fair usage limit?

On many plans, things suddenly feel “broken.”
Pages stop loading properly, maps lag, and even basic apps can struggle. That’s because speeds are often reduced to very low levels. With Koala Sim, there’s no usage trigger that slows you down, you keep the same high-speed connection throughout your trip.

If data keeps working, isn’t that still unlimited?

Technically, that’s how providers define it, but it’s not very helpful in real life.
Data that technically works at very slow speeds isn’t the same as usable internet. Koala Sim defines unlimited as unlimited high-speed data, without throttling once you’ve used “too much.”

How can I spot an unlimited eSIM with hidden limits?

Look closely at the wording.
If you see phrases like “fair usage policy,” “speeds may be reduced,” or “excessive usage,” there’s probably a cap involved. Koala Sim keeps it simple and transparent: no fair usage policy and no hidden speed limits.

Does hotspot or tethering slow things down?

On many plans, yes, even if they’re called unlimited.
Some providers limit hotspot data separately or slow it down quickly. Koala Sim allows unlimited hotspot and tethering at the same speeds you get on your phone, with no separate caps.

Can I actually use unlimited eSIM data for work?

You can, if it’s genuinely unlimited.
Koala Sim customers regularly hotspot laptops, join video calls, upload files, and use large amounts of data without running into speed drops or restrictions.

So what does “truly unlimited” really mean?

It’s simple.
No fair usage policy, no daily high-speed limits, and no usage-based throttling. That’s how Koala Sim defines unlimited data, and that’s how it’s designed to work.