---
title: Set Border Lerp Size
description: "Play 0x59, server → client."
---

`play` · `0x59` · **clientbound** (server → client)

Animates the world border diameter from `oldDiameter` to `newDiameter` over `speed` milliseconds. The server sends it when the border is set to grow or shrink over time. The client interpolates the size locally.

Sent by the server, read by the client. Listen for it with `client.on("SetBorderLerpSize", (data) => …)` on the receiving side.

## Fields

| Field | Type | Notes |
|---|---|---|
| `oldDiameter` | Double |  |
| `newDiameter` | Double |  |
| `speed` | VarLong |  |

## Send it

```ts
await client.sendPacket("SetBorderLerpSize", {
  oldDiameter: /* Double */,
  newDiameter: /* Double */,
  speed: /* VarLong */,
});
```

Field aliases listed under Notes are accepted as alternative keys when writing.

Source: [`src/Core/Versions/776/Packets/play/clientbound/SetBorderLerpSize.ts`](https://github.com/GDLev/mc-protocol/blob/master/src/Core/Versions/776/Packets/play/clientbound/SetBorderLerpSize.ts)