Paying for 100 Mbps but Only Getting 12 MB/s? Here’s What’s Actually Happening…

Newan Kumanayaka

4 min read

·

Jul 24, 2026

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Many people subscribe to a 100 Mbps Fibre internet package and expect files to download at 100 MB/s. When they only see speeds of around 10–12 MB/s, they assume something is wrong with their internet.

In reality, this is completely normal.

My ISP Package

I use SLT-Mobitel Speed-Based Unlimited Fibre.

As of early 2026, these packages include:

• 100 Mbps Download Speed
• 50 Mbps Upload Speed
• Unlimited Data (No Fair Usage Policy/FUP)
• Unlimited Voice Calls
• Speeds are provided on a best-effort basis, meaning performance may vary depending on network congestion and server availability.

Some standard unlimited packages also have restrictions on services such as BitTorrent, Peer-to-Peer (P2P), VPNs, and Telegram, while certain packages may have different policies.

Mbps vs MB/s

This is where most people get confused. Internet Service Providers advertise speeds in Megabits per second (Mbps).

However, Windows, macOS, Steam, Chrome, and most download managers display download speeds in Megabytes per second (MB/s).

The difference is:

• 1 Byte = 8 Bits
• 1 MB = 8 Mb

So to calculate your maximum download speed:

100 Mbps ÷ 8 = 12.5 MB/s

Likewise, for uploads:

50 Mbps ÷ 8 = 6.25 MB/s

This means that even though your package says 100 Mbps, the highest download speed you’ll normally see is approximately 12.5 MB/s.

Why Do I Usually See Only 10–12 MB/s?

A download speed between 10 MB/s and 12 MB/s is actually very good and indicates your connection is performing close to its maximum capacity.

The slight difference from the theoretical maximum is caused by:

• Network protocol overhead (TCP/IP, HTTPS, etc.)
• Server upload limits
• Internet routing between you and the server
• Wi-Fi signal quality or local network performance
• Temporary congestion during peak usage periods

Because of these factors, consistently reaching exactly 12.5 MB/s is uncommon.

Down & Up Time Examples

File Size Approximate Time (100 Mbps Connection) — 100 MB~8s, 500 MB~40s, 1 GB~1m20s, 10 GB~13–14m

Key Takeaway

A 100 Mbps Fibre connection does not mean you’ll download files at 100 MB/s.

Instead:

• 100 Mbps ≈ 12.5 MB/s maximum download speed
• 50 Mbps ≈ 6.25 MB/s maximum upload speed

So if you’re downloading files at around 10–12 MB/s, your internet connection is performing almost exactly as expected.

The biggest misunderstanding comes from confusing megabits (Mbps) with megabytes (MB/s).

Remember this simple rule:

MB/s = Mbps ÷ 8

So before assuming your ISP is delivering slower speeds than promised, check whether you’re comparing Mbps with MB/s — they’re two different — -units of measurement.

Speedtest and download managers are measuring different things, even though they’re both measuring your internet speed.

Speedtest (Ookla)

When you run a Speedtest, it reports your speed in Megabits per second (Mbps).

Your result:

• Download: 92.99 Mbps
• Upload: 47.15 Mbps

These numbers are already in Mbps, which is the unit your ISP advertises.

Download Managers (Chrome, Steam, Edge, etc.)

When you download a file, most applications display the speed in Megabytes per second (MB/s).

To compare them, convert Mbps to MB/s:

• Download: 92.99 Mbps ÷ 8 = 11.62 MB/s
• Upload: 47.15 Mbps ÷ 8 = 5.89 MB/s

That’s why your browser shows around 10–12 MB/s while Speedtest shows 93 Mbps — they’re actually reporting the same speed using different units.

MeasurementUnitYour SpeedISP Package Mbps, 100 Mbps Speedtest Result Mbps 92.99 Mbps Actual Download MB/s 11.6 MB/s Upload MB/s 5.9 MB/s

Why Doesn’t Speedtest Show MB/s?

ISPs around the world market internet packages in bits per second because networking equipment (routers, switches, Ethernet, fiber optics, etc.) measures bandwidth in bits.

Storage devices and operating systems, on the other hand, measure files in bytes.

For example:

• Internet package → 100 Mbps
• File size → 100 MB

Since 1 Byte = 8 Bits, you must divide by /8 to estimate the download speed you’ll see when downloading files.

Your Connection

You have:

• Package: 100 Mbps ↓ / 50 Mbps ↑
• Speedtest: ~93 Mbps ↓ / ~47 Mbps ↑
• File downloads: ~10–12 MB/s

These numbers all match and indicate that your connection is performing normally. A Speedtest result of around 93 Mbps is very good for a 100 Mbps plan, since a small amount of bandwidth is always used for protocol overhead and network efficiency.