Theoretical Throughput Calculator
Wi-Fi (802.11n / ac / ax) vs Ethernet in real-world conditions.
Connection type and conditions
Table of Contents
Comprehensive Theoretical Throughput Guide
What is theoretical vs real throughput?
Advertised speeds (e.g. 'Wi-Fi 1200 Mbit/s' or 'Gigabit Ethernet') refer to the physical layer (PHY) or line rate – the raw bit rate at the radio or cable. Actual usable throughput is always lower: protocol overhead (Ethernet, IP, TCP), and for Wi-Fi, distance, interference, and sharing between devices. Understanding the difference helps you choose the right connection and set realistic expectations for file transfers, streaming, and backups.
How throughput works
Throughput is measured in bits per second (Mbps or Gbps). The path from application to wire or radio involves several layers:
- Application data: The actual file or stream you send or receive.
- Protocol overhead: TCP, IP, and Ethernet (or Wi-Fi MAC) add headers, acknowledgments, and gaps; this typically consumes a few percent on Ethernet and much more on Wi-Fi.
- Physical layer (PHY): The maximum raw rate the link can carry. What the manufacturer advertises is usually this PHY rate, not the throughput you get at the application.
- PHY rate (theoretical): Maximum physical layer speed in ideal conditions. Shown on router boxes and Ethernet specs.
- TCP/IP overhead: On Ethernet, about 2–6% of the line rate is lost to headers and inter-frame gaps; TCP achieves roughly 94–98% of line rate.
- MIMO (streams): Multiple antennas allow higher PHY rates; real throughput scales with streams but not linearly due to overhead and contention.
- Channel width: 20, 40, 80, or 160 MHz: wider channels allow higher PHY but need a clear band and are more sensitive to interference.
Ethernet vs Wi-Fi at a glance
Ethernet
- Stable, predictable throughput (94–98% of line rate)
- No sharing: full link for one device (per port)
- Low latency, no radio contention
- Requires cable; fixed placement
- Fast Ethernet to 10 Gbit/s common in practice
Wi-Fi
- Throughput varies: 40–70% of PHY typical, lower when far or noisy
- Shared medium: all clients share the same AP
- Distance, walls, and interference reduce speed
- Mobility; no cable
- Wi-Fi 4 (n) to Wi-Fi 6 (ax); 2.4 and 5 GHz
Benefits of understanding throughput
- Realistic expectations: You know why a '1200 Mbit/s' router does not give 1200 Mbit/s at the application.
- Better choices: Pick Ethernet vs Wi-Fi and the right Wi-Fi generation (n, ac, ax) and channel width for your use case.
- Troubleshooting: If measured speed is below the real-world range, you can look for interference, drivers, or a slow disk/NAS.
- Planning: Estimate backup or transfer times using real throughput, not advertised PHY.
Limitations and why your speed may vary
- Wi-Fi throughput depends heavily on environment (distance, walls, number of clients, interference). The calculator gives typical ranges, not guarantees.
- Ethernet throughput can be limited by the slowest element: cable, NIC, switch, or the other endpoint (e.g. NAS disk speed).
- Speed tests measure throughput to a specific server; your real use (e.g. to a NAS or another country) may differ.
- Older devices may not support the highest PHY (e.g. 802.11n only); the link negotiates the lowest common capability.
Advertised speeds on routers and boxes are almost always the theoretical (PHY) maximum, not the throughput you will see in real use. Use this calculator's real-world range to set expectations; for Wi-Fi, choose the conditions (ideal / typical / poor) that best match your environment.
Evolution of standards
Ethernet has evolved from 10 Mbit/s to 100 (Fast), 1000 (Gigabit), 2.5G, 5G, and 10 Gbit/s. Wi-Fi generations (802.11n = Wi-Fi 4, 802.11ac = Wi-Fi 5, 802.11ax = Wi-Fi 6) have increased PHY rates through wider channels, more streams (MIMO), and better modulation. Each generation improves real-world throughput and, in the case of Wi-Fi 6, efficiency in dense environments.
Choosing the right connection
Consider these factors when planning your network:
- Use case: Large file transfers, backups, or video editing benefit from Ethernet or high-end Wi-Fi (ac/ax, 80–160 MHz). Browsing and light streaming work with modest throughput.
- Latency: Gaming and VoIP prefer low latency; Ethernet is more consistent than Wi-Fi.
- Mobility: Laptops and phones need Wi-Fi; desktops and servers can use Ethernet for best performance.
- Environment: Many walls or neighbors mean more interference; use 5 GHz and consider Ethernet for critical links.
Throughput comparison chart
The reference table below (section 8) lists theoretical and real-world throughput for each option in this calculator. Use it to compare Ethernet and Wi-Fi generations at a glance.
Theoretical throughput (PHY/line rate) is a useful reference, but real-world throughput is what you get for transfers and streaming. Ethernet gives predictable, high throughput with low overhead; Wi-Fi offers mobility with variable throughput depending on conditions. Use this calculator to see typical ranges for your connection type and, for Wi-Fi, to estimate speed in ideal, typical, or poor conditions. For the best mix of speed and stability, prefer Ethernet where possible and choose Wi-Fi 5 or 6 with sufficient channel width when you need wireless.
Theoretical vs Real Throughput Overview
Theoretical (PHY) speed is the maximum physical layer rate. Real throughput is what applications see after protocol overhead and, for Wi-Fi, environmental factors. This calculator shows both so you can set realistic expectations.
- Ethernet: ~94–98% of line rate in practice
- Wi-Fi: typically 40–70% of PHY; varies with conditions
- Use 'conditions' in the calculator for Wi-Fi (ideal / typical / poor)
Ethernet
Ethernet provides a dedicated, full-duplex link per port. Overhead comes mainly from frame headers (Ethernet, IP, TCP) and inter-frame gaps; TCP typically achieves about 94–98% of the line rate. So 1 Gbit/s Ethernet usually delivers around 940–980 Mbit/s for file transfers. Fast Ethernet (100 Mbit/s), Gigabit (1 Gbit/s), 2.5G, and 10 Gbit/s are common; real throughput scales with line rate.
- Stable throughput; minimal variation
- No sharing per port; full link for one device
- Low latency; no radio contention
- Real throughput ~94–98% of line rate
Wi-Fi 4 (802.11n)
802.11n (Wi-Fi 4) operates in 2.4 GHz and 5 GHz with channel widths of 20 or 40 MHz and up to 4 spatial streams. Theoretical PHY ranges from about 72 Mbps (20 MHz, 1 stream) to 600 Mbps (40 MHz, 4 streams). Real-world throughput is typically 50–60% of PHY in good conditions and can drop significantly with distance or interference. Still common on older devices and in 2.4 GHz-only environments.
- 20 or 40 MHz channels; 1–4 streams
- 2.4 and 5 GHz; 2.4 GHz often congested
- Real throughput ~50–60% of PHY in good conditions
- Max PHY 600 Mbps (40 MHz, 4×4)
Wi-Fi 5 (802.11ac)
802.11ac (Wi-Fi 5) is 5 GHz only, with 80 or 160 MHz channels and up to 8 streams. PHY rates go from 433 Mbps (80 MHz, 1 stream) to over 6.9 Gbps (160 MHz, 8 streams). In practice, 80 MHz and 1–2 streams are common; real throughput is often 50–70% of PHY. Delivers hundreds of Mbps to over 1 Gbps in ideal conditions. Replaced by Wi-Fi 6 for new deployments but still widely used.
- 5 GHz only; 80 or 160 MHz channels
- 1–8 streams; 80 MHz 2 streams very common
- Real throughput ~50–70% of PHY
- Up to ~1.7 Gbps PHY (160 MHz, 2 streams) in this calculator
Wi-Fi 6 (802.11ax)
802.11ax (Wi-Fi 6) operates in 2.4 and 5 GHz with 20, 40, 80, or 160 MHz channels and improved modulation (OFDMA, higher MCS). PHY rates are higher than Wi-Fi 5 for the same channel width and streams; real-world efficiency is often 60–80% in good conditions. Better performance in dense environments (many devices). Wi-Fi 6E adds 6 GHz for more spectrum.
- 2.4 and 5 GHz; 20–160 MHz channels
- OFDMA; better in dense environments
- Real throughput often 60–80% of PHY in good conditions
- Higher PHY than ac for same width/streams
Why real throughput is lower
Ethernet
Frame headers (Ethernet, IP, TCP/UDP), acknowledgments, and inter-frame gaps reduce usable throughput. TCP typically achieves about 94–98% of the line rate on a healthy link. So 1 Gbit/s Ethernet usually gives around 940–980 Mbit/s for file transfers.
Wi-Fi
Wi-Fi adds MAC overhead (headers, acknowledgments, contention), and the PHY rate is shared among all clients on the same AP. Distance and obstacles lower the modulation (MCS), so the PHY rate drops. Interference and collisions further reduce throughput. Real-world Wi-Fi often reaches 40–70% of the theoretical PHY in typical conditions; in poor conditions it can be much lower.
Reference table (Mbps)
| Connection | Theoretical | Real-world (min – max) |
|---|---|---|
| Ethernet 100 Mbit/s (Fast Ethernet) | 100 Mbps | 94 – 98 Mbps |
| Ethernet 1 Gbit/s (Gigabit) | 1000 Mbps | 940 – 980 Mbps |
| Ethernet 2.5 Gbit/s | 2500 Mbps | 2350 – 2450 Mbps |
| Ethernet 10 Gbit/s | 10000 Mbps | 9400 – 9800 Mbps |
| Wi-Fi 4 (802.11n) – 20 MHz, 1 stream | 72 Mbps | 25 – 45 Mbps |
| Wi-Fi 4 (802.11n) – 40 MHz, 1 stream | 150 Mbps | 50 – 90 Mbps |
| Wi-Fi 4 (802.11n) – 40 MHz, 2 streams | 300 Mbps | 100 – 180 Mbps |
| Wi-Fi 4 (802.11n) – 40 MHz, 4 streams | 600 Mbps | 200 – 350 Mbps |
| Wi-Fi 5 (802.11ac) – 80 MHz, 1 stream | 433 Mbps | 200 – 300 Mbps |
| Wi-Fi 5 (802.11ac) – 80 MHz, 2 streams | 867 Mbps | 400 – 600 Mbps |
| Wi-Fi 5 (802.11ac) – 160 MHz, 2 streams | 1733 Mbps | 700 – 1100 Mbps |
| Wi-Fi 6 (802.11ax) – 80 MHz, 1 stream | 600 Mbps | 350 – 500 Mbps |
| Wi-Fi 6 (802.11ax) – 80 MHz, 2 streams | 1200 Mbps | 600 – 900 Mbps |
| Wi-Fi 6 (802.11ax) – 160 MHz, 2 streams | 2400 Mbps | 1200 – 1800 Mbps |
Best practices
- For maximum throughput and stability, use Ethernet (Gigabit or higher) when the device can be wired.
- Place the Wi-Fi access point centrally and avoid thick walls or metal between device and AP to get closer to 'ideal' conditions.
- Use 5 GHz for Wi-Fi when possible; less congestion than 2.4 GHz. Wi-Fi 6 (802.11ax) improves efficiency in dense environments.
- Channel width: 80 MHz or 160 MHz gives higher PHY but needs a clear channel; 40 MHz can be more stable in noisy areas.
- Speed tests measure real throughput; compare with this calculator's real-world range. If you are well below the range, check for interference, outdated drivers, or a slow NAS/disk.