Anchor Rod Length

Anchor rod length is a stack, so this page stacks it

Nothing clever here: the rod has to reach from its embedded end, up through the concrete, the grout, the leveling nuts if there are any, the base plate, the washer and the top nut, and still show enough thread above the nut for the erector. Each of those is a number somebody decided. Type them, see the sum, and see the sketch so you can tell at a glance that you did not leave out the grout.

Piece	Who decides it
Embedment	the EOR — from the anchorage design, measured to the top of concrete
Grout	the EOR or the base plate detail — often 1" or 1 1/2"
Leveling nut + washer	the erection method; turn it off above if the plate sets on shims
Base plate	the design
Top washer + nut	the hardware spec
Thread projection	shop or erector standard — enough to run the nut on and see thread

What this page does not do

• It does not size the anchor, choose the embedment, or check pullout, breakout or shear. Embedment is an input here because it is the engineer's answer, not ours.
• It does not know your nut heights. A heavy hex nut is close to the rod diameter in height, but "close to" is not a dimension — type the real one from the hardware you are buying.
• It does not add a fudge for tolerance. If your shop always adds an inch, add it in the projection line so it shows up in the sum instead of hiding in someone's head.
• It does not round to stock lengths on its own — it tells you the next 1" and 2" increments so you can.

Questions detailers ask

How do you work out anchor rod length?

Add the stack from the embedded end up: embedment, grout, the leveling nut and washer if the plate is set on them, the base plate, the top washer and nut, and the clear thread projection above the nut. Every one of those is a number somebody decided; this page adds the six lines and shows the sum, so a piece left out is visible instead of buried. Worked with this page's own defaults: 12" embedment + 1 1/2" grout + 1 1/8" leveling nut and washer + 1 1/4" base plate + 1 1/8" top washer and nut + 1" projection = 18.000" — a 1'-6" rod.

Does anchor rod length include the embedment?

Yes. Embedment is measured from the end of the rod to the top of concrete, and it is part of the length you order. It is an input on this page because it is the engineer of record's answer from the anchorage design, not something a length calculator decides.

What changes if the base plate sets on shims instead of leveling nuts?

Turn the leveling nut off. That line drops out of the sum and out of the sketch, and the grout line carries the space under the plate. Leaving a leveling nut in a stack that does not have one is one of the two ways this dimension usually goes wrong.

How much thread should project above the top nut?

That is a shop or erector standard rather than a code number: enough to run the nut down and still see thread. Type your own standard into the projection line so it shows up in the sum, instead of living in somebody's head and being forgotten on the one job that mattered.

Checking it yourself

12" embedment + 1 1/2" grout + 1 1/8" leveling nut and washer + 1 1/4" base plate + 1 1/8" washer and nut + 1" projection = 1'-6". If the sum on this page does not match the pieces you typed, do not use it — tell us.