Coming from someone fully capable of eyeballing most things within ridiculous closeness, there are secrets, that once learned give you an advantage.**
[ul]
[li]3 oz of meat – a “normal” serving – is approximately the size of your palm and 1/2" thick[/li][li]cup your hand tightly, it will form a little scrunchy cup in the palm, fill that cup to just under the place where the fingers meet the palm – it should be roughly a teaspoon[/li][li]a yard is the easy one – grab a piece of fabric/yarn/string between the thumb and forefinger, hold it to your nose, then reach your arm out to the side, keeping the end you plan to cut by your nose – if you’re short, turn your head away from the direction your arm is, if tall, face forward – cut where the fabric touches your nose. I am 5’3", my husband is 6’ it is within 3" of a yard with either of us[/li][li]the thumbnail is roughly 1/2"[/li][li]a slice of american cheese is roughly one ounce[/li][li]a dollar bill is roughly 6" long – or half a foot[/li][/ul]
Liquids are tough – we are confronted with fucked up portioning all the time, so you just have to practice to get liquids down. A few things to keep in mind – 3 tsp = 1 tbsp, 1 tbsp = 1 oz, 8 oz in a cup. There are other tricks that I use to be able to eyeball things, but it’s almost all based on remembering the measurements of other things for comparison, like a sheet of paper is 8.5"x11" and knowing what things are denser than others. It helps me to know that fudge is denser than cookies, so a lb of fudge will take up less space than a lb of cookies.
**obviously, we are all different sizes, and there will be some variation, but like I said, it is all within amazing closeness.