What Is the Fastest Speed an iPhone Can Support?

By John Papiewski

The iPhone 5 has 5 GHz Wi-Fi and 4G LTE cellular data technology.
i Justin Sullivan/Getty Images News/Getty Images

The speed at which a smartphone downloads data strongly affects its usefulness for everyday business tasks. The iPhone 5 model uses 3G, 4G LTE and Wi-Fi for email, Web browsing and other data functions. The fastest download speed the iPhone supports is about 40 million bits per second on Wi-Fi networks. Cellular network speeds, which have traditionally lagged behind Wi-Fi, are beginning to catch up.

Data Connections

The iPhone uses two main technologies through which it receives data: cellular networks and Wi-Fi. Wi-Fi is a short-range technology in use in many homes and businesses; the maximum distance between the phone and the network access point is 230 feet. Wi-Fi's advantage is its faster download speeds. In addition to voice calling, cellular service providers offer data plans for smartphone customers. These data services span whole geographic areas, covering metropolitan areas and major highways. Though download speeds are lower than with Wi-Fi, they provide much wider coverage. When the iPhone detects a strong Wi-Fi signal, it automatically connects if it has the password; otherwise, it relies on the cellular network for data access.

Wi-Fi Speeds

Wi-Fi technology has evolved since its introduction in 1997. In 2012, a typical Wi-Fi network has a maximum speed of 54 Mbps. Newer 802.11n Wi-Fi supports speeds up to 600 Mbps. The newest current standard, 802.11ac, has theoretical speeds of nearly 7 Gbps. Because speed impacts battery life, mobile devices seldom attain the maximum data rates on Wi-Fi networks, although desktop PCs have the potential for better performance. The iPhone 5's communication chips allow the use of the newer 5 GHz radio signal on 11n networks; this is a significant speed improvement over the 4s and older iPhone models, which use only the older 2.4 GHz signal.

3G and 4G Speeds

In the U.S., cellular phone service providers offer 3G and 4G wireless data networks. The maximum speed for the older 3G service is 1 Mbps; the fastest for 4G LTE is 173 Mbps. The iPhone 5 can use either 3G or 4G LTE cellular service; older models support 3G technology only.

Real-World Tests

Tests conducted by technicians at CNET on the iPhone 5 reveal an average download speed of 9.78 Mbps on a 4G LTE network, compared to 1.71 Mbps with an iPhone 4S on 3G. Gizmodo tested the iPhone 5 on Wi-Fi networks, measuring a download speed of 37.8 Mbps using the 5 GHz signal, versus 8.7 Mpbs when using 2.4 GHz Wi-Fi.

Signal Strength and Network Traffic

The iPhone's performance in daily use strongly depends not only on whether it connects to Wi-Fi or 4G network, but also on the state of the network. A busy data network will have significantly slower downloads compared to lightly used ones. The strength of the wireless signal also affects download performance; you see optimal speeds only when the phone indicates the maximum number of signal bars.