Help me read a vernier caliper

[Bricago]

Several web searches have explained how to read the metric scale to the second decimal place, but I don't understand how the Imperial units are read. I guess the first question is, how accurate is this tool? 1/32", 1/64", etc...

Photo two shows the outer diameter of the washer a hair over 1-1/4". I believe that the third hash mark is aligned correctly. What would this measurement be?

Photo four shows the inner diameter just past 5/16", and again the third hash mark is aligned. What would this measurement be?

Those nine hashmarks are throwing me. I'm hoping for a clear explanation.

 

[franzdom]

The major marks are 16ths and the resolution is 1/8 of that or 1/128th of an inch.
There are nine marks to divide each 16th by 8x more resolution.
Just like the metric has 11 marks to divide each mm by 10.

Let's look at picture #4:
The reading is 8.5mm on the bottom, the left bottom mark is between 8 & 9mm. The first mark is a zero so the 6th one is 5/10th of a mm. just like that on the top.
The top shows it's first mark between 5/16 & 6/16ths and the 3th mark on the very top lines up, (it looks like the 4th to me but that's not the point of this discussion, and may be the photo playing tricks) meaning you are 5/16 plus 2/128ths (remember the first mark is zero).

To double check:
5/16 + 2/128 = 42/128 = 21/64" = 8.3mm
5/16 + 3/128 = 43/128 = 43/128" = 8.5mm

Photo 2 I get 1-1/4" + 2/128" = 1-17/64"

 

[Lassen Forge]

The hash marks below the "window" are the next decimal (metric or decimal inch) or fraction (conventional inch) below the lowest reading on the "main" scale... start at the left hash mark (which is "0") and count across until the hash below the window lined up perfectly with the line above (you may need a magnifying glass to see it).

Used to be a common interview test my boss would throw out, right after the question "Can you read a vernier caliper?"

In the examples above, looks like #1 and 2 is 39.9 mm, #3 and 4 is 13.5 mm... but it's been so long since I've had to use a real one. (and having the dial one makes it moot!)

 

[HammerMechanic]

The major marks are 16ths and the resolution is 1/8 of that or 1/128th of an inch.
There are nine marks to divide each 16th by 8x more resolution.
Just like the metric has 11 marks to divide each mm by 10.

Let's look at picture #4:
The reading is 8.5mm on the bottom, the left bottom mark is between 8 & 9mm. The first mark is a zero so the 6th one is 5/10th of a mm. just like that on the top.
The top shows it's first mark between 5/16 & 6/16ths and the 3th mark on the very top lines up, (it looks like the 4th to me but that's not the point of this discussion, and may be the photo playing tricks) meaning you are 5/16 plus 2/128ths (remember the first mark is zero).

To double check:
5/16 + 2/128 = 42/128 = 21/64" = 8.3mm
5/16 + 3/128 = 43/128 = 43/128" = 8.5mm

Photo 2 I get 1-1/4" + 2/128" = 1-17/64"

This is the how to read them. I came up with 1 17/16" or 1.265 on the O.D. or 32.2 mm which is 1.267.
And 11/32" or .343 on I.D. or 8.7 mm which is .342

 

[Bricago]

The major marks are 16ths and the resolution is 1/8 of that or 1/128th of an inch.
There are nine marks to divide each 16th by 8x more resolution.
Just like the metric has 11 marks to divide each mm by 10.

Let's look at picture #4:
The reading is 8.5mm on the bottom, the left bottom mark is between 8 & 9mm. The first mark is a zero so the 6th one is 5/10th of a mm. just like that on the top.
The top shows it's first mark between 5/16 & 6/16ths and the 3th mark on the very top lines up, (it looks like the 4th to me but that's not the point of this discussion, and may be the photo playing tricks) meaning you are 5/16 plus 2/128ths (remember the first mark is zero).

To double check:
5/16 + 2/128 = 42/128 = 21/64" = 8.3mm
5/16 + 3/128 = 43/128 = 43/128" = 8.5mm

Photo 2 I get 1-1/4" + 2/128" = 1-17/64"

Thank you for this explanation. This makes perfect sense. I know the shadow in the photos is right at the critical reading point for the inches side, but I read you.