The formula to convert degrees Fahrenheit (°F) to degrees Celsius (°C) is:

```

°C = (°F - 32) × 5/9

```

So, to convert 800°F to Celsius, we plug in the value:

```

°C = (800 - 32) × 5/9

°C = (768) × 5/9

°C = 425.56

```

Therefore, 800°F is equal to 425.56°C.