# PTTL

> Return the expiration in milliseconds of a key.

## Arguments

<ParamField body="key" type="str" required>
  The key 
</ParamField>

## Response

<ResponseField type="int" required>
  The number of milliseconds until this expires, negative if the key does not exist or does not have an expiration set.
</ResponseField>

<RequestExample>
```py Example
redis.set("key1", "Hello")

assert redis.pttl("key1") == -1

redis.expire("key1", 1000)

assert redis.pttl("key1") > 0

redis.persist("key1")

assert redis.pttl("key1") == -1
```
</RequestExample>