> For the complete documentation index, see [llms.txt](https://docs.openalgo.in/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openalgo.in/api-documentation/v1/data-api/optionsymbol.md).

# OptionSymbol

Get the option symbol based on underlying, expiry, offset (ATM/ITM/OTM), and option type. This endpoint resolves the correct strike price automatically.

## Endpoint URL

```http
Local Host   :  POST http://127.0.0.1:5000/api/v1/optionsymbol
Ngrok Domain :  POST https://<your-ngrok-domain>.ngrok-free.app/api/v1/optionsymbol
Custom Domain:  POST https://<your-custom-domain>/api/v1/optionsymbol
```

## Sample API Request (ATM Option)

```json
{
  "apikey": "<your_app_apikey>",
  "underlying": "NIFTY",
  "exchange": "NSE_INDEX",
  "expiry_date": "30DEC25",
  "offset": "ATM",
  "option_type": "CE"
}
```

## Sample cURL Request

```bash
curl -X POST http://127.0.0.1:5000/api/v1/optionsymbol \
  -H 'Content-Type: application/json' \
  -d '{
  "apikey": "<your_app_apikey>",
  "underlying": "NIFTY",
  "exchange": "NSE_INDEX",
  "expiry_date": "30DEC25",
  "offset": "ATM",
  "option_type": "CE"
}'
```

## Sample API Response (ATM Option)

```json
{
  "status": "success",
  "symbol": "NIFTY30DEC2525950CE",
  "exchange": "NFO",
  "lotsize": 65,
  "tick_size": 5,
  "freeze_qty": 1800,
  "underlying_ltp": 25966.4
}
```

## Sample API Request (ITM Option)

```json
{
  "apikey": "<your_app_apikey>",
  "underlying": "NIFTY",
  "exchange": "NSE_INDEX",
  "expiry_date": "30DEC25",
  "offset": "ITM3",
  "option_type": "PE"
}
```

## Sample API Response (ITM Option)

```json
{
  "status": "success",
  "symbol": "NIFTY30DEC2526100PE",
  "exchange": "NFO",
  "lotsize": 65,
  "tick_size": 5,
  "freeze_qty": 1800,
  "underlying_ltp": 25966.4
}
```

## Sample API Request (OTM Option)

```json
{
  "apikey": "<your_app_apikey>",
  "underlying": "NIFTY",
  "exchange": "NSE_INDEX",
  "expiry_date": "30DEC25",
  "offset": "OTM4",
  "option_type": "CE"
}
```

## Sample API Response (OTM Option)

```json
{
  "status": "success",
  "symbol": "NIFTY30DEC2526150CE",
  "exchange": "NFO",
  "lotsize": 65,
  "tick_size": 5,
  "freeze_qty": 1800,
  "underlying_ltp": 25966.4
}
```

## Request Body

| Parameter    | Description                                                                                                                                                  | Mandatory/Optional | Default Value                      |
| ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------ | ---------------------------------- |
| apikey       | Your OpenAlgo API key                                                                                                                                        | Mandatory          | -                                  |
| underlying   | Underlying symbol (NIFTY, BANKNIFTY, SENSEX) or a futures symbol that already carries the expiry, such as `NIFTY28OCT25FUT`                                  | Mandatory          | -                                  |
| exchange     | Underlying's exchange. Any value in the shared `VALID_EXCHANGES` list passes validation; the practical values are NSE\_INDEX, NSE, BSE\_INDEX, BSE, NFO, BFO | Mandatory          | -                                  |
| expiry\_date | Expiry date in DDMMMYY format. Not required when `underlying` already includes the expiry                                                                    | Optional           | Derived from `underlying`          |
| strike\_int  | Strike interval, positive integer or `null`. Omit it so the actual strikes in the instrument master are used, which is recommended                           | Optional           | Derived from the instrument master |
| offset       | Strike offset: ATM, ITM1-ITM50, OTM1-OTM50                                                                                                                   | Mandatory          | -                                  |
| option\_type | Option type: CE or PE (lowercase accepted)                                                                                                                   | Mandatory          | -                                  |
| strategy     | Deprecated. Accepted and ignored; it will be removed in a future version                                                                                     | Optional           | -                                  |

These eight fields are the complete `OptionSymbolSchema`. Any other field returns HTTP 400. If you omit both `expiry_date` and an expiry-bearing `underlying`, the request fails in the service rather than at validation.

## Response Fields

| Field           | Type   | Description                |
| --------------- | ------ | -------------------------- |
| status          | string | "success" or "error"       |
| symbol          | string | Resolved option symbol     |
| exchange        | string | Options exchange (NFO/BFO) |
| lotsize         | number | Lot size for the option    |
| tick\_size      | number | Minimum price movement     |
| freeze\_qty     | number | Maximum quantity per order |
| underlying\_ltp | number | Current underlying price   |

## Understanding Offset

| Offset     | Description      | CE Strike Direction | PE Strike Direction |
| ---------- | ---------------- | ------------------- | ------------------- |
| ATM        | At-The-Money     | Closest to LTP      | Closest to LTP      |
| ITM1-ITM50 | In-The-Money     | Below LTP           | Above LTP           |
| OTM1-OTM50 | Out-of-The-Money | Above LTP           | Below LTP           |

## Lot Sizes

Lot sizes come from the downloaded instrument master, not from a fixed table. The exchanges revise them, so read `lotsize` from the response rather than hard-coding a value. The examples on this page reflect one particular master contract.

## Notes

* The offset is calculated based on actual **strike intervals** in the database
* **underlying\_ltp** shows the current price used for ATM calculation
* Use this endpoint to **discover the symbol** before placing orders
* For placing orders directly with offset, use [OptionsOrder](/api-documentation/v1/orders-api/optionsorder.md)

***

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