Advertised vs Real Internet Speeds
The gap between the ad and your actual connection — measured, not estimated
Every internet ad says "up to". Up to 500 Mbps. Up to 1 Gig. That phrase is doing a lot of work: it describes the maximum possible speed under ideal conditions — not what arrives at your router on a Tuesday evening.
This entire site exists because of that gap. We compare the advertised number against the median of real speed tests run by actual customers, provider by provider, ZIP code by ZIP code.
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Why real speeds fall short
The gap is not (usually) fraud — it is physics and economics. Cable networks share bandwidth across a neighborhood, so evening congestion cuts everyone's speed. DSL degrades with every meter of copper between you and the cabinet. 5G depends on tower distance, band, and load. Even fiber loses some throughput to WiFi, old routers, and in-home wiring.
But the size of the gap varies enormously by provider and technology — and that variation is exactly what the ads hide.
- Fiber typically delivers the highest share of its advertised speed in our measurements
- Cable performs well off-peak but sags in the evening when the neighborhood is online
- DSL and fixed wireless show the widest gaps between the ad and the measurement
- The same provider can deliver 90% of advertised in one ZIP code and 40% in another
Who delivers closest to the ad
Based on our aggregate measurements, here is how the main technologies and providers stack up on the real-to-advertised ratio — with the caveat that your specific ZIP code is what matters, and we publish that number for every provider:
Fiber connections dominate the top of our delivery-ratio measurements, and AT&T's fiber footprint is the largest we track. Dedicated lines mean no neighborhood congestion — what is advertised is close to what arrives, morning and evening alike.
The same dedicated-line physics as AT&T Fiber, with the same result: measured speeds that track the advertised number closely. Note that Frontier's DSL service under the same brand behaves completely differently — verify which technology serves your address.
Cable delivers a solid share of advertised speed most of the day, with the gap opening during evening congestion when the neighborhood shares the line. The delivery ratio varies meaningfully between ZIP codes — the same provider can measure 90% in one area and 50% in another.
5G home providers advertise ranges rather than single numbers — arguably the most honest framing in the industry. Delivery depends on tower distance and load: strong-signal addresses measure at the top of the advertised band, weak-signal ones below it. The trial periods exist for a reason.
See the exact delivery ratio for every provider in your ZIP code
How we measure
Our speed data comes from Measurement Lab (M-Lab), a nonprofit that runs one of the largest open internet measurement platforms in the world. Millions of people run M-Lab speed tests every month; each test records the measured throughput and the network it ran on.
We aggregate 24 months of tests per ZIP code and provider, take the median (not the flattering average), and publish it next to the advertised speed. We also show the 25th percentile — the speed you can expect on the slower days — and measured latency.
No provider pays to improve their numbers. The data is what residents actually measured.
Frequently asked questions
Are ISPs lying about their speeds?
"Up to" claims are legal because the maximum is technically achievable in ideal conditions. The practical question is what share of the advertised speed a provider typically delivers at your address — which is what our measured data shows.
How accurate is M-Lab data?
M-Lab is an independent nonprofit platform used by researchers and regulators, with an open methodology and public raw data. Individual tests vary (WiFi, device, time of day), which is why we use the median of many tests over 24 months rather than single results.
What percentage of advertised speed should I expect?
It varies by provider and area. Fiber connections frequently measure 80%+ of advertised; cable and 5G vary more widely; DSL often falls far short. Enter your ZIP code to see the actual ratio for every provider at your address.
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Coverage: FCC BDC · Speeds: M-Lab NDT (24-month median) · Pricing: provider websites · Updated 2026-07-12