How to Check Your Business Internet Speed (And What to Do If It's Slow)

Slow internet costs UK businesses real money. Staff waiting for files to upload, video calls freezing mid-meeting, cloud applications lagging — it all adds up. Before you can fix the problem, you need to measure it properly.

This guide shows you how to accurately test your business internet speed, understand what the numbers mean, and take action if performance is not where it should be.

How to Run a Business Speed Test

Consumer speed test sites work, but for business purposes you need a more structured approach:

Step 1: Use a Reliable Testing Tool

The best options for UK businesses:

• Speedtest by Ookla (speedtest.net) — the industry standard; select a server close to your location for accurate results
• Fast.com (by Netflix) — simple and quick, good for a basic check
• Ofcom broadband speed checker — useful for comparing your speed against what your ISP promised
• Your ISP own speed test — tests the connection to their network specifically, useful for support tickets

Step 2: Test Properly

A single speed test at 9am on a quiet Monday tells you very little. For meaningful results:

• Test wired, not wireless — connect a laptop directly to your router with an Ethernet cable to eliminate WiFi variables
• Close other applications — pause cloud backups, close browser tabs, stop streaming
• Test at different times — run tests during peak hours (10am, 2pm) and off-peak to see how performance varies
• Test from multiple locations — if you have multiple offices or floors, test from each
• Run at least three tests — and average the results to smooth out anomalies

Understanding Your Results

Speed tests report three key metrics:

Download Speed

How fast data arrives at your network. Affects web browsing, email, streaming, and downloading files. Measured in Mbps (megabits per second).

Upload Speed

How fast data leaves your network. Critical for cloud backups, video conferencing (sending your video), VoIP calls, and uploading large files. Often overlooked — many broadband connections have much slower upload than download speeds.

Latency (Ping)

The time it takes for a data packet to travel to the server and back, measured in milliseconds (ms). Low latency is essential for real-time applications like VoIP, video calls, and remote desktop sessions. Under 20ms is excellent; over 100ms causes noticeable lag.

Jitter

The variation in latency over time. High jitter makes VoIP calls choppy and video calls stutter, even if your average speed is fine. Under 30ms is acceptable; under 10ms is ideal.

What Speed Does Your Business Actually Need?

There is no single answer — it depends on what you do and how many people are doing it simultaneously:

• Basic office work (email, web, documents): 5-10 Mbps per user
• Video conferencing (Teams, Zoom): 5-10 Mbps per concurrent call
• Cloud-heavy workflows (SaaS, cloud storage, VDI): 10-20 Mbps per user
• Large file transfers (design, video, engineering): 50+ Mbps upload

As a rough guide, a 20-person office doing standard office work with regular video calls needs at least 100 Mbps download and 30 Mbps upload — though more is always better for headroom.

Why Your Speed Might Be Slower Than Expected

If your test results do not match what your ISP promised, here are the most common causes:

Network Congestion

Shared broadband connections (FTTC, FTTP on some packages) slow down during peak hours when your neighbours are also online. This is less of an issue with leased lines, which provide dedicated bandwidth.

Poor Router Performance

Consumer-grade routers cannot handle the traffic demands of a busy office. If your router is the bottleneck, upgrading to business-grade hardware often delivers an immediate improvement.

WiFi Interference

Microwave ovens, Bluetooth devices, neighbouring WiFi networks, and thick walls all degrade wireless performance. The speed issue might not be your internet connection at all — it might be your internal WiFi.

Outdated Cabling

Cat5 Ethernet cables cannot support gigabit speeds. If your office still has Cat5 (not Cat5e or Cat6), the cabling itself is limiting your throughput.

ISP Throttling or Contention

Some cheaper business broadband packages have high contention ratios — meaning you share bandwidth with many other businesses. Leased lines offer a 1:1 contention ratio (dedicated bandwidth just for you).

What to Do If Your Speed Is Too Slow

Quick Fixes

• Restart your router — clears memory and re-establishes connections; surprisingly effective
• Check for bandwidth hogs — large cloud backups, Windows updates, or streaming can saturate a connection
• Schedule heavy traffic — set backups and updates to run overnight
• Use QoS settings — prioritise VoIP and video traffic on your router
• Switch DNS servers — using Cloudflare (1.1.1.1) or Google (8.8.8.8) DNS can improve browsing speed

Longer-Term Solutions

• Upgrade your broadband package — move from FTTC to FTTP (full fibre) for faster, more reliable speeds
• Add a backup connection — a 4G/5G failover line provides redundancy and can load-balance with your primary connection
• Consider a leased line — dedicated, symmetric bandwidth with guaranteed speeds and SLAs; ideal for businesses where connectivity is mission-critical
• Upgrade your internal network — replace old routers, switches, cabling, and access points

For a detailed comparison of broadband options available to UK businesses, see our business broadband comparison guide.

Monitoring Speed Over Time

A one-off test gives you a snapshot. For ongoing visibility, consider:

• Automated speed monitoring tools — services like ThousandEyes or PingPlotter run continuous tests and alert you to degradation
• Router and firewall dashboards — business-grade routers show real-time bandwidth usage per device and per application
• Managed IT monitoring — your IT provider can set up alerts that flag slowdowns before they impact productivity

If your business relies on connectivity across multiple locations, SD-WAN technology can optimise traffic routing automatically. Learn more in our guide to multi-site business connectivity.

When to Escalate

Contact your ISP if:

• Speeds are consistently more than 20% below your contracted rate
• You experience frequent dropouts or packet loss
• Latency spikes during business hours

Under Ofcom rules, if your ISP cannot resolve the issue within a reasonable time, you may be able to exit your contract without penalty. Keep records of your speed tests as evidence.