# Fetching a Discount Curve

The `/discount_curve` endpoint returns a schedule of discount factors between two dates at a specified frequency. Use this when you need to discount multiple future cash flows back to present value.

***

## Basic Example

```python
import requests

url = "https://api.bluegamma.io/v1/discount_curve"
headers = {"x-api-key": "your_api_key"}

params = {
    "index": "SOFR",
    "start_date": "0D",
    "end_date": "5Y",
    "frequency": "6M"
}

response = requests.get(url, headers=headers, params=params)
data = response.json()

for point in data["curve"]:
    print(f"{point['date']}: {point['discount_factor']:.6f}")
```

```bash
curl -X GET "https://api.bluegamma.io/v1/discount_curve?index=SOFR&start_date=0D&end_date=5Y&frequency=6M" \
  -H "x-api-key: your_api_key_here"
```

**Response:**

```json
{
  "start_date": "2026-04-01",
  "end_date": "2031-04-01",
  "index": "SOFR",
  "valuation_time": "2026-04-01T20:57:50.523152",
  "is_end_of_month": true,
  "frequency": "6M",
  "curve": [
    { "date": "2026-04-01", "discount_factor": 1.0 },
    { "date": "2026-04-30", "discount_factor": 0.997063 },
    { "date": "2026-10-31", "discount_factor": 0.978594 },
    { "date": "2027-04-30", "discount_factor": 0.960977 },
    { "date": "2027-10-31", "discount_factor": 0.943836 },
    { "date": "2028-04-30", "discount_factor": 0.927581 },
    { "date": "2028-10-31", "discount_factor": 0.911458 },
    { "date": "2029-04-30", "discount_factor": 0.895746 },
    { "date": "2029-10-31", "discount_factor": 0.879728 },
    { "date": "2030-04-30", "discount_factor": 0.863909 },
    { "date": "2030-10-31", "discount_factor": 0.847782 },
    { "date": "2031-04-30", "discount_factor": 0.831898 }
  ],
  "timestamp": "2026-04-01T20:57:27"
}
```

### Response fields

| Field             | Description                                             |
| ----------------- | ------------------------------------------------------- |
| `start_date`      | Start date of the curve                                 |
| `end_date`        | End date of the curve                                   |
| `index`           | The interest rate index used                            |
| `valuation_time`  | When the curve was calculated                           |
| `is_end_of_month` | Whether dates are aligned to month-ends                 |
| `frequency`       | Spacing between curve points                            |
| `curve`           | Array of points, each with `date` and `discount_factor` |
| `timestamp`       | When the underlying market data was captured            |

### Curve point fields

| Field             | Description                                                                                           |
| ----------------- | ----------------------------------------------------------------------------------------------------- |
| `date`            | The future date (ISO 8601 format)                                                                     |
| `discount_factor` | The present value of 1 unit of currency received on that date. Starts at 1.0 and decreases over time. |

***

## Parameters

| Parameter         | Required | Description                                                                |
| ----------------- | -------- | -------------------------------------------------------------------------- |
| `index`           | Yes      | Interest rate index (e.g., `SOFR`, `SONIA`, `6M EURIBOR`)                  |
| `start_date`      | Yes      | Start of the curve. Relative (`0D`, `1Y`) or absolute (`2026-04-01`)       |
| `end_date`        | Yes      | End of the curve. Relative (`5Y`, `10Y`, `30Y`) or absolute (`2031-04-01`) |
| `frequency`       | Yes      | Spacing between points: `1M`, `3M`, `6M`, or `1Y`                          |
| `valuation_time`  | No       | Historical timestamp (ISO 8601) for reproducibility                        |
| `is_end_of_month` | No       | Align dates to month-ends. Defaults to `true`                              |

***

## Practical example: Discounting a loan schedule

```python
import requests

url = "https://api.bluegamma.io/v1/discount_curve"
headers = {"x-api-key": "your_api_key"}

# Get semi-annual discount factors for the next 3 years
params = {
    "index": "SOFR",
    "start_date": "0D",
    "end_date": "3Y",
    "frequency": "6M"
}

response = requests.get(url, headers=headers, params=params)
curve = response.json()["curve"]

# Semi-annual loan payments
payments = [50000] * 6  # 6 payments of 50,000

total_pv = 0
for i, payment in enumerate(payments):
    # Skip the first curve point (date = today, DF = 1.0)
    df = curve[i + 1]["discount_factor"]
    pv = payment * df
    total_pv += pv
    print(f"{curve[i + 1]['date']}: {payment:>10,} x {df:.6f} = {pv:>10,.2f}")

print(f"\nTotal Present Value: {total_pv:,.2f}")
```

***

## `/discount_curve` vs `/discount_factor`

|               | `/discount_curve`                                  | `/discount_factor`                          |
| ------------- | -------------------------------------------------- | ------------------------------------------- |
| **Returns**   | Full schedule of discount factors                  | A single discount factor                    |
| **API calls** | 1 call for the entire curve                        | 1 call per date                             |
| **Best for**  | Loan/bond valuation, DCF models, batch discounting | Quick lookups, single cash flow discounting |

Use `/discount_curve` when you need discount factors for multiple dates. Use [`/discount_factor`](https://bluegamma.io/documentation/integrations/api/how-to-guides/getting-discount-factors) when you only need one.

***

## Visualising a discount curve

<figure><img src="https://3184259219-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmmQPefoflG1RwUnUKKBR%2Fuploads%2Fgit-blob-ae5889202f1dffa0a0ff6c590b871a8744ae5794%2Fdiscount-curve-sofr-10y.png?alt=media" alt="Discount curves for SOFR, SONIA, and 6M EURIBOR over 10 years"><figcaption><p>SOFR, SONIA, and 6M EURIBOR discount curves: 10-year, quarterly frequency</p></figcaption></figure>

***

## Related Endpoints

| If you need...           | Use                                                                                                              |
| ------------------------ | ---------------------------------------------------------------------------------------------------------------- |
| A single discount factor | [`/discount_factor`](https://bluegamma.io/documentation/integrations/api/how-to-guides/getting-discount-factors) |
| Zero rates               | [`/zero_rate`](https://bluegamma.io/documentation/integrations/api/how-to-guides/fetching-zero-rates)            |
| Forward rates            | [`/forward_rate`](https://bluegamma.io/documentation/integrations/api/how-to-guides/getting-forward-rates)       |
| A forward curve          | [`/forward_curve`](https://bluegamma.io/documentation/integrations/api/how-to-guides/getting-a-forward-curve)    |

***

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