Not a direct answer to the question posed, so I’ll tiny-type it. I simply measure the length between my last and middle knuckle of my index finger on my left hand. I am at the age where the bone will not grow anymore, so the measurement will stay accurate. I simply remember the number, but I suppose you could tattoo the measurement down so you wouldn’t forget. That way, you would not have to worry about sagging/stretching skin altering your measuring tool.

Ha! No way – my weight fluctuates greatly, so I know it would either get bigger (I sure hope not) or smaller (think positive, Luna, it will get smaller!)

I guess it depends were you have the tattoo, If it’s somewhere that grows on a regular basis and your are male, then I’m guessing it won’t stay accurate!

As long as you have no significant weight changes, it should stay accurate until you reach the age where your skin starts to stretch and sag. Of course if it was on your flanks it would change every time you breathe, and if it was on your upper arm or thigh it would change every time you exercise, but if it was on your forearm or some other place that is fairly consistent in size then you should be fine.

I know a woman who got a tattoo of a long-stemmed red rose on her breast when she was young. Now it’s a weeping willow.

Strange you asked this…I have always wanted a tattoo of Bush on my ass…..

I gotta give you cred for a question that made me laugh out loud!

Nothing marked on your skin could possibly be relied upon for “accuracy”. Your skin is elastic, and can change based on body temperature, ambient temperature, hydration, illness, muscle flexing, insect bites… the list goes on.

If you had some kind of bone implant, then… perhaps. Better to measure your fingers, arms, legs, etc. and use them as rough benchmarks. Don’t expect more than ±¼” or so accuracy.

I seriously dout if the length would stay accurate, for the reasons @CyanoticWasp stated. Using bone lengths, as @Dan_DeColumna stated would be more accurate. I’ve lost some weight (muscle mass) and a chest tattoo has contracted horizontally but not vertically.

You should just duct tape one to your arm.It’s far more accurate.

I’m more interested in the MacGyver moments in which you expect to find yourself! And if you were a spy, wouldn’t you worry about the information you put on it?

Ok so follow up question: Besides pi (please stop laughing, this is serious), what other useful info, that is nearly impossible to remember, could I incorporate into a tattoo?

pi is useful?

So when someone goes to a very skillful tattoo artist, and the tattoo is like a xerox copy of whatever she wanted, has the artist in fact erred in her task?

um, okay: cocktail recipes, conversion charts, stellar constellation navigational charts…

Seriously constellation nav is what I had in mind, as one aspect.

Well, if you are going to measure things with your ruler tattoo, you might not want to put it on your arms, since it will make it difficult to measure anything. Best to put it on your lap.
If you put it on your inner thigh, you might even get more dates. Depending.

You know that popular one seen on so many young ladies’ lower back…the one they now have nicknamed a “trampstamp”...I found this out from my niece…it’s those really cool-looking Chinese letters…that one? Well, it means, “Beef with Broccoli.” Saw it on the menu at my neighborhood Chinese Restaurant.

A trampstamp would be any tattoo just above a womans ass.
If the tattoo touches the crack of her ass, it is a New Jersey Plate.

I’d incorporate the equation for changing celsius to fahrenheit.

And you could mine the awesome “Time Travelers Essentials Shirt”: for ideas, too, although that might not be exactly what you were looking for.

Nope a ruler tattoo wont work because your skin stretches with age. It’s a very funny question. Do you know the joke about the dude who tattooed a dollar on his penis? He said he likes to see his money grows, he likes it when his wife blows his money and he likes to play with his money.

I would not suggest a tattoos with straight lines at all, further more any good tattoo artist will not do a tattoo with long straight lines anyway.

Essential Info for Time Travelers
I’d start there. That’s a ton of tattoo work though. It might be less painful to just learn it.

No, it would not stay accurate. May I suggest you simply sew a fabric tape measure to all your shirts?

How about a nice conversion table it could really come in handy and wouldn’t matter if it changed shape or size! You would have to put it somewhere where you can see the whole thing though.

@Dan_DeColumna That’s what I meant to link above!! Don’t know how I left out the link part without noticing till right now, hahaha. :)

@fireinthepriory: I noticed that you intended to link to it (”...”:), so I tossed it up there for you.

@Dan_DeColumna Thanks! :)

Doubtful if it’s on the penis.

Your plan seems to me to be ill considered. Since the areas of the body least prone to skin stretching are likely to me the most difficult for you to read.

Get yourself a Leatherman multi tool. They come with rulers and are more versatile!

I’ve had a tattoo of King Henry the Eighth for more than ten years.

People still have no trouble recognizing him.

@PacificRimjob I was just thinking of Mike Tyson with his Mao tattoo.

Contacted a tattoo artist friend of mine who answered: No, but it will stay until muscles grow, or shrink, or skin wrinkles.

I’m rethinking my idea against getting a tattoo of a ruler: I think it’s a great idea; go with Genghis Khan.

Not literally.

Would it be accurate for the rest of one’s life?

I’d say that if it was tattooed on the inward top part of a shin where there’s almost nothing but skin and a relatively broad, flat bone surface, then it would probably be accurate for most of your life.

I say that because I’m 63, and I don’t see any skin sag or wrinkling there yet.

However, I’ve lost about 1” in height in the last 40 years, so if I live to be 100, I might lose another inch.

That means that I’ll have lost about 2.77% of my height.
2.77% of 12”=about ⅓”.

I think a some of our height loss is due to vertebral compression, so I’d say that the length loss would be ⅓” at the most.

I guess your forehead would be another good area too, as long as it was only a 6” ruler, you kept it well-moisturized, ate well, and used mucho sun block.

Um, I’ve seen a tattoo of a ruler up a man’s forearm.

The beginning of it unseen up to the wrist.

The ruler “started” at the knuckles of his closed fist.

Why shouldn’t handballing have a visible metric?