> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# BITCOUNT

> Count set bits in a string.

Use `BITCOUNT` to count the bits set to 1 in the string stored at a key.

Without a range the whole value is counted. `<start>` and `<end>` restrict the count to a part of the value and are interpreted as byte offsets by default, or as bit offsets when `BIT` is given. Both ends are inclusive and may be negative to count backwards from the end of the value, where `-1` is the last byte or bit. A missing key is treated as an empty string and returns `0`.

`BITCOUNT` is the usual way to read a bitmap built with [`SETBIT`](/docs/redis/commands/bitmap/setbit), for example to count how many users were active on a given day when each user has a fixed bit position.

## Syntax

```redis theme={"system"}
BITCOUNT <key> [<start> <end> [BYTE | BIT]]
```

## Arguments

| Argument                      | Required | Repeatable | Description                                                                                        |
| ----------------------------- | -------- | ---------- | -------------------------------------------------------------------------------------------------- |
| `<key>`                       | Yes      | No         | Redis key targeted by the command.                                                                 |
| `<start> <end> [BYTE \| BIT]` | No       | No         | Range to count. Offsets are byte-based unless `BIT` is given; negative offsets count from the end. |

## Response

The reply reports the result of the operation. Error replies have the same shape in RESP2 and RESP3 and are surfaced as exceptions by the SDKs below.

| Protocol | Reply   |
| -------- | ------- |
| RESP2    | Integer |
| RESP3    | Integer |

<Note>
  Client libraries often decode bulk strings, maps, sets, and numeric strings into language-native values. The table describes the Redis wire reply.
</Note>

## Examples

TCP examples use the TLS `REDIS_URL` from the Upstash console. REST examples use `UPSTASH_REDIS_REST_URL` and `UPSTASH_REDIS_REST_TOKEN`.

<AccordionGroup>
  <Accordion title="Redis CLI" icon="terminal">
    ```bash theme={"system"}
    BITCOUNT my-key
    ```
  </Accordion>

  <Accordion title="@upstash/redis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    import { Redis } from "@upstash/redis";

    const redis = Redis.fromEnv();

    const bits = await redis.bitcount(key);
    ```
  </Accordion>

  <Accordion title="upstash_redis" icon="python" iconType="brands">
    ```python theme={"system"}
    from upstash_redis import Redis

    redis = Redis.from_env()
    result = redis.bitcount("my-key")
    print(result)
    ```
  </Accordion>

  <Accordion title="ioredis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    import Redis from "ioredis";

    const redis = new Redis(process.env.REDIS_URL!);
    const result = await redis.bitcount("my-key");
    console.log(result);
    ```
  </Accordion>

  <Accordion title="node-redis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    import { createClient } from "redis";

    const client = await createClient({ url: process.env.REDIS_URL })
      .on("error", console.error)
      .connect();
    const result = await client.bitCount("my-key");
    console.log(result);
    ```
  </Accordion>

  <Accordion title="redis-py" icon="python" iconType="brands">
    ```python theme={"system"}
    import os
    import redis

    client = redis.from_url(os.environ["REDIS_URL"])
    result = client.bitcount("my-key")
    print(result)
    ```
  </Accordion>

  <Accordion title="go-redis" icon="golang" iconType="brands">
    ```go theme={"system"}
    package main

    import (
        "context"
        "fmt"
        "os"

        "github.com/redis/go-redis/v9"
    )

    func main() {
        opts, err := redis.ParseURL(os.Getenv("REDIS_URL"))
        if err != nil {
            panic(err)
        }
        client := redis.NewClient(opts)
        result, err := client.BitCount(context.Background(), "my-key", nil).Result()
        if err != nil {
            panic(err)
        }
        fmt.Println(result)
    }
    ```
  </Accordion>

  <Accordion title="jedis" icon="java" iconType="brands">
    ```java theme={"system"}
    import java.net.URI;

    import redis.clients.jedis.Jedis;

    try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {
      Object result = jedis.bitcount("my-key");
      System.out.println(result);
    }
    ```
  </Accordion>

  <Accordion title="redis-rs" icon="rust" iconType="brands">
    ```rust theme={"system"}
    use redis::TypedCommands;

    fn main() -> redis::RedisResult<()> {
        let url = std::env::var("REDIS_URL").expect("REDIS_URL is not set");
        let client = redis::Client::open(url)?;
        let mut connection = client.get_connection()?;

        let result = connection.bitcount("my-key")?;
        println!("{result:?}");
        Ok(())
    }
    ```
  </Accordion>
</AccordionGroup>


## Related topics

- [BITCOUNT](/docs/redis/sdks/py/commands/bitmap/bitcount.md)
- [Changelog](/docs/redis/overall/changelog.md)
- [SETBIT](/docs/redis/commands/bitmap/setbit.md)
- [BITOP](/docs/redis/commands/bitmap/bitop.md)