Internet FAQ · Speed
How many Mbps is 1 gig?
1 gig internet is 1,000 Mbps. Internet speeds use decimal units, so one gigabit per second (1 Gbps) equals 1,000 megabits per second.[1] That is ten times the FCC's 100 Mbps download benchmark, and it matches the FCC's long-term goal of 1 Gbps download.[2] At full speed, a gig plan moves about 125 megabytes per second.[1]
| Plan speed | In Mbps | Top transfer rate |
|---|---|---|
| 300 Mbps | 300 | 37.5 MB per second |
| 500 Mbps | 500 | 62.5 MB per second |
| 1 gig (1 Gbps) | 1,000 | 125 MB per second |
Transfer rates are AT&T's theoretical figures.[1]
Is 1 Gb the same as 1 GB?
No. Plans are sold in gigabits (Gb). Files and data are measured in gigabytes (GB). A byte is 8 bits, so 1 GB of data is 8,000 megabits.[1] On a full 1 Gbps line, a 1 GB file takes about 8 seconds, by that math.[1]
Why your speed test may show less
Wi-Fi, older phones and laptops, and Ethernet ports or cables not built for gigabit speeds can hold a device below the plan speed.[1] Test with a computer plugged into the router by cable before you blame the plan. Also check the upload number: cable and DSL plans usually upload slower than they download, while fiber is often the same both ways.[3]
For gig speed with fast uploads, learn how to spot real fiber and find it at your address in our fiber internet guide.
More internet questions
Sources
- AT&T: Mbps vs Gbps, Understanding the differences. AT&T, Mbps vs Gbps, accessed October 27, 2026. 1 Gbps equals 1,000 Mbps, eight bits per byte, theoretical transfer rates, and equipment limits; the 1 GB file time is our arithmetic at full sustained speed. ↩
- FCC: FCC Increases Broadband Speed Benchmark (news release, March 14, 2024). FCC, FCC Increases Broadband Speed Benchmark, news release of March 14, 2024, accessed October 27, 2026. The 100/20 Mbps benchmark and the 1 Gbps/500 Mbps long-term goal; the multiple is our arithmetic. ↩
- AT&T: Is 500 Mbps fast?. AT&T, Is 500 Mbps fast?, accessed October 27, 2026. Cable and DSL typically asymmetrical; fiber often symmetrical. ↩
Written with AI assistance and checked against the sources listed. Editorial policy