Have you ever needed a measuring cup, but didn’t want to use your cooking measuring cups, because you were going to measure something like an automotive fluid?

You can make your own measuring device.

I did this using a clever unit conversion, and a metric fact.

How many milliliters are there in a fluid ounce?

1 fl oz = 30 ml

How many fluid ounces are there in 100 ml?

100 ml = 3.4 fl oz

So, you can kinda fake a conversion based on thinking of 100ml as 3 fluid ounces. It’s not accurate, but… for a lot of things, it’s good enough.

There’s a metric fact/hack that makes it easy to make the measuring cup:

**1 gram of water = 1 ml**

If you have a food or postal scale, you can just pour water into a bottle, and weigh it, and then you can mark off the volume.

I decided to make a measuring bottle that’s roughly 4 ounces.

I marked off 33, 66, 100, and 133 ml, and also marked off 1, 2, 3, and 4 ounces.

The ounces are a little off – the actual measurement is a little less than what’s marked – but it’s close enough.

If you’re wondering how I got it to ignore the weight of the jar – it’s a feature on all scales called “tare”. To use it, put the jar on the scale, and then press the “T” button.

The scale will reset to 0g. It’s ignoring the weight of the bottle.