A gigabyte (GB) is a unit of data: 1 GB equals 1,000,000,000 bytes. When you stream, GB describes how much data is used, while Mbps describes how quickly data travels. How much streaming uses depends on the service, video quality, and data settings; Netflix’s estimates range from up to 0.3 GB per hour on Low to up to 7 GB per hour for UHD on High.
What does GB mean?
A gigabyte is a measure of data quantity. The National Institute of Standards and Technology (NIST) defines 1 GB as 109 bytes, or 1,000,000,000 bytes. It is a decimal unit commonly used to describe file sizes and data allowances.
GB and GiB are different units
A gibibyte (GiB) is a binary unit: 1 GiB equals 230 bytes, or 1,073,741,824 bytes. NIST lists GB and GiB separately because their symbols refer to different quantities. A GB is not a gigabit (Gb), either: bytes and bits are different units.
For unit definitions, see NIST’s definitions of SI units and binary prefixes and its GiB glossary entry.
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GB versus Mbps: data amount versus speed
GB measures an amount of data. Mbps, or megabits per second, measures a rate: how quickly data can travel over a connection. A data allowance stated in GB and a connection-speed recommendation stated in Mbps answer different questions. A speed recommendation does not tell you how many GB you can use.
For example, Netflix recommends stable speeds of at least 3 Mbps for 720p, 5 Mbps for 1080p, and 15 Mbps for 4K. These are Netflix recommendations for video quality, not estimates of GB consumed per hour or guarantees that every household will get that quality. See Netflix’s recommended internet speeds.
How much data does streaming use?
There is no single GB-per-hour figure for streaming across all services. As one service-specific example, Netflix publishes the following per-device estimates for its data settings. They are estimates from Netflix, not universal streaming rates.
| Netflix setting | Netflix’s stated data use |
|---|---|
| Low | Up to 0.3 GB per hour |
| Medium | Up to 0.7 GB per hour |
| High, SD | Up to 1 GB per hour |
| High, HD | Up to 3 GB per hour |
| High, UHD/4K | Up to 7 GB per hour |
| Auto | The app adjusts use and quality according to connection conditions |
Netflix also describes mobile settings in approximate viewing hours per GB: Automatic, about 4 hours; Save Data, about 6 hours; and Maximum Data, which can use 1 GB in 20 minutes or more depending on device and network speed. Netflix says its highest setting is intended for unlimited data plans. These are Netflix’s own estimates, not averages for other services. Details are on its data-use settings page.
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Estimate your data use or viewing time
Use the estimate for the service and setting you actually use. Multiply its estimated GB per hour by viewing hours to estimate data consumption; divide your available data by the hourly estimate to estimate viewing time. Because provider figures are estimates, the arithmetic is a planning aid, not a promise of exact usage.
- Estimate consumption: estimated GB per hour × hours watched = estimated GB used.
- Estimate viewing time: data allowance in GB ÷ estimated GB per hour = estimated hours.
For example, using Netflix’s stated High HD estimate of up to 3 GB per hour, one hour of viewing would use up to about 3 GB under that estimate. The result applies to that Netflix setting and estimate; it should not be generalized to every streaming service or viewing condition.
What can change the viewing experience?
Netflix says its data settings can be changed, and restricting data use may reduce video quality. It also notes that congestion anywhere along the connection can affect quality or cause playback problems; the strength of a home connection and simultaneous network use can affect the viewing experience. Netflix does not quantify how much each factor changes data volume, so its published hourly figures should not be treated as exact usage for an individual viewing session. See How Netflix streams videos.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.A historical Netflix figure is not a current default
In a May 5, 2016 announcement, Netflix Director of Product Innovation Eddy Wu said, “The default setting will enable you to stream about 3 hours of TV shows and movies per gigabyte of data.” Netflix described that then-default cellular setting as approximately 600 kilobits per second. This is historical context from 2016, not a statement of Netflix’s current default or a general streaming estimate. The announcement is at Netflix’s 2016 cellular data controls announcement.
If you run a prerecorded YouTube stream
GB describes data quantity, not the internet speed or data use of a particular creator’s setup. For a separate creator use case—keeping uploaded videos live on YouTube around the clock—StreamNeo runs the loop from the cloud after you upload a recording or playlist, add your YouTube stream key, and start the stream. That service is for prerecorded video streamed to YouTube; it does not explain or change a viewer’s GB-per-hour consumption.
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