---
title: "ustruct"
aliases:
    - firmwareapi/micropython/ustruct.html
    - firmwareapi/micropython/ustruct.md
    - chapter/firmwareapi/micropython/ustruct
---

See Python [struct](https://docs.python.org/3/library/struct.html) for more information.

Supported size/byte order prefixes: `@, <, >, !`.

Supported format codes: `b, B, h, H, i, I, l, L, q, Q, s, P, f, d` (the latter 2 depending on the floating-point support).

## Methods

#### ustruct.calcsize(fmt)

Return the number of bytes needed to store the given `fmt`.

#### ustruct.pack(fmt, v1, v2, ...)

Pack the values `v1, v2, ...` according to the format string `fmt`. The return value is a bytes object encoding the values.

#### ustruct.pack\_into(fmt, buffer, offset, v1, v2, ...)

Pack the values `v1, v2, ...` according to the format string `fmt` into a buffer starting at `offset`. `offset` may be negative to count from the end of buffer.

#### ustruct.unpack(fmt, data)

Unpack from the `data` according to the format string `fmt`. The return value is a tuple of the unpacked values.

#### ustruct.unpack\_from(fmt, data, offset=0)

Unpack from the `data` starting at `offset` according to the format string `fmt`. `offset` may be negative to count from the end of buffer. The return value is a tuple of the unpacked values.