The formula for converting Fahrenheit to Celsius is:

```

°C = (°F - 32) * 5/9

```

Substituting 70°F into the formula, we get:

```

°C = (70°F - 32) * 5/9

```

```

°C = (38) * 5/9

```

```

°C = 21.11

```

Therefore, 70 degrees Fahrenheit is approximately equal to 21.11 degrees Celsius.