Reliable BLE Data Transfer: Handling MTU, Throughput & Chunking

Sooner or later, every BLE developer runs into the same wall: you need to send more than 20 bytes at a time. Maybe it is a firmware image, a batch of sensor readings, or a configuration payload. You fire off a write and… only the first 20 bytes arrive. The rest is silently dropped.
The root of this problem is the MTU (Maximum Transmission Unit) — the maximum number of bytes a single BLE packet can carry. Understanding MTU, knowing how to negotiate it, and building a reliable chunking layer on top of it is essential for any real-world BLE application.
In this article we will cover everything you need to know: what MTU actually is, how to negotiate it on iOS and Android, the difference between write types, how to build a chunking protocol, and how to maximize throughput.
Let’s get started!




