Building for 3G: Performance Budgets That Matter

Coverage is not speed

TCRA’s statistics for the quarter ending June 2025 put population coverage at 98.6 percent for 2G, 93.4 percent for 3G, 92.0 percent for 4G and 26 percent for 5G. Geographical coverage was much thinner: 75 percent for 3G, 75 percent for 4G and 5.9 percent for 5G. A bar of 4G in Dar es Salaam does not describe a road in Katavi.

DataReportal’s Digital 2025 report, using GSMA Intelligence, counted 79 million mobile connections at the start of 2025 and classed 85.8 percent of them as 3G, 4G or 5G. That label means the SIM can attach to a broadband network. It does not mean the person is on a fast plan, or even using data. TanzaniaInvest, reporting TCRA’s first quarter of 2025, put average mobile internet speed at 12.5 Mbps. The Bank of Tanzania’s 2025 payments report still counted more feature phones than smartphones.

A budget you can test

Set the budget on the first screen, not on the whole site. A practical bar for a page someone must finish on a slow radio link is about 200 KB of compressed transfer before they can read and act, including the type, the picture and the script. That is a design limit, not a law from the regulator. If the first screen is a photograph, a font file and a chat widget, you have already spent it.

Serve images at the size they are shown. Prefer one photograph over a carousel. Do not autoplay video. Subset fonts or use the system font for body text. Keep the payment and the form on the first document so a stalled second request does not trap the task. Cache nothing you need the user to see fresh, and cache the picture bytes you do not intend to change.

Test the path, not the lab phone

Throttle a mid-range Android to a slow 3G profile and complete the one task the page exists for: pay, book, or read the price. Count the requests before that task is possible. If it fails when the radio drops for ten seconds, add a retry that does not wipe the form. Feature-phone customers still need an SMS or USSD door beside the website. The smartphone path and the basic-phone path are both part of the product.