"One inch of water"

[jeff47]

4. Your measure is far more subjective

"keep uniformly damp without allowing soil to dry out, but not drenched"

That's way more subjective. And wrong - you'd want the tomato plant to be a little drier than you describe.

Most people (well me, anyway) are going to have a much better idea of how much water is needed to meet this description than by having to guess what is meant by 'inch of water' or by having to calculate that volume.

It's really not that hard to calculate.

If watering by hose, see how long it takes to fill a small container 1" deep. Multiply by the size of the area you're watering vs. the size of the container.

If watering by sprinkler, put the same container in the area covered by the sprinkler. Water for a few minutes. Measure how deep the water is. From that you can calculate how long it takes to put out 1" of water.