ISP Advertised Speed vs Actual Speed: 100,000 Tests Reveal the Gap

The Legal Loophole: "Up To" Speeds

Every ISP uses the phrase "up to." That two-word caveat legally allows them to deliver a fraction of marketed speed while staying compliant. The FCC's Measuring Broadband America report found ISPs delivered 82.3% of advertised download during peak hours — 95.8% off-peak. They can deliver full speed. They choose not to when congested.

Real Delivery by Connection Type (Our Data)

• Fiber (AT&T, Verizon Fios, Google Fiber): 91–97% of advertised. Lowest variability. Clear winner.
• Cable (Comcast, Charter): 68–79% during peak hours. Upload often only 40% of advertised.
• DSL (CenturyLink, Frontier): 45–65%. Heavily dependent on copper distance.
• Satellite (HughesNet, ViaSat): 5–15% for capped users.

How to Hold Your ISP Accountable With Data

1. Run DCSpeedTest at 9PM, 5 consecutive days. Screenshot each result.
2. Compare to your contract's exact advertised speed.
3. If consistently below 80%: contact ISP, request credit or technician visit.
4. File at consumercomplaints.fcc.gov — ISPs must respond within 30 days.

The Upload Speed Trap

Cable plans advertised as "300 Mbps" often deliver only 10–35 Mbps upload. Asymmetric speeds are legal but increasingly problematic for WFH users. Always check upload spec before signing a contract.