There is no direct conversion between liters and proof liters. Proof liters are a measure of alcohol content, while liters are a measure of volume.

In the United States, the proof of a spirit is defined as twice its alcohol by volume (ABV). For example, a spirit that is 40% ABV is 80 proof.

In other countries, the proof of a spirit may be defined as its alcoholic strength by volume (ASBV). ASBV is calculated by multiplying the ABV by 1.75. For example, a spirit that is 40% ABV is 70 ASBV.

To convert liters to ASBV proof liters, you can use the following formula:

```

ASBV proof liters = liters x ASBV

```

For example, to convert 1 liter of a spirit that is 40% ABV to ASBV proof liters, you would use the following formula:

```

ASBV proof liters = 1 liter x 70 = 70 ASBV proof liters

```

Therefore, 1 liter of a spirit that is 40% ABV is equal to 70 ASBV proof liters.