Last updated July 28, 2026
ADD is a calculator that runs at the AutoCAD command line. You add numbers up, one after another, and it keeps the running total in front of you — without alt-tabbing to another program and losing your place in the drawing.
It is by Craig Carr of Superior Designs, written in 1996, and the header records that it was a bonus winner in the November 1996 issue of Cadalyst. He also wrote the CHT text standardiser and the LS layer setter on this site.
Why bother, when AutoCAD has CAL
A fair question. Full AutoCAD has shipped a geometry calculator for a long time, and every computer has a calculator application on it.
The case for this one is the running total. AutoCAD’s calculator evaluates an expression and gives you an answer; this keeps adding to what you already have, which is the shape of the job when you are totalling up a column of lengths off a drawing, or a bill of quantities, or a set of areas. You are not composing one expression, you are accumulating.
The other case is that it is on the command line where your hands already are. For a quick sum during a drafting session that matters more than it sounds.
Command reference
The file defines a single command, ADD.
It carries a proper error handler that saves the previous one and puts it back, and restores command echo on the way out — so cancelling out of it mid-sum leaves your session as it was. That is better behaviour than several larger routines in this library manage.
How to load it
Unzip Add.zip and load add.lsp with APPLOAD, or put it in the Startup Suite. A calculator is only useful if it is already there when you want it. No support files. Our AutoLISP guide covers loading.
Step-by-step usage
- Type ADD.
- Enter your numbers one at a time as it prompts, watching the running total.
- Finish when you have your answer.
Note that this adds numbers you type. It does not measure anything in the drawing — if you want lengths totalled straight off the geometry, ADDLENGTH does that instead, and ZONE totals areas and lengths by layer.
Compatibility notes
1996, so written-for rather than tested-on. It does arithmetic and prints to the command line, which is about as durable as AutoLISP gets — there is very little here that could break.
Plain AutoLISP with no dialog boxes and no Express Tools calls, so nothing requires the full product; LT users on LT 2024 or later, the release that brought AutoLISP to LT, should be able to run it. See what runs on AutoCAD LT. It touches nothing in your drawing at all, which makes it the safest thing on this site to try.
Download
| Name: | Add |
| Description: | AutoCAD built in calculator |
| Type: | AutoCAD AutoLISP Routine |
| Author: | Craig Carr |
| File Size: | 2 Kb |
| Cost: | Free |
| Worked on: | AutoCAD |
| Download File: | Add.zip |
The description calls it AutoCAD’s built-in calculator. It is not — it is a separate routine you load, unrelated to the CAL command that ships with AutoCAD.
Related routines
- ADDLENGTH — totals lengths measured from the drawing rather than typed.
- ZONE — totals area or length by layer.
- CHT — the same author’s text standardiser.