The Diameter Inch Calculator
Enter the lines from your bid, get total dia-inches, weld hours, and weld labor dollars. Every factor on this page is editable, so the output follows your history, not ours.
The Calculator
This prices butt-weld labor only. It does not carry handling, supports, NDE, or paint, and it does not argue with your productivity factors. Socket welds are usually carried separately.
| Size (NPS) | Wall | Material | Butt Welds | Dia-Inches | |
|---|---|---|---|---|---|
| 144 | |||||
| 120 | |||||
| 90 | |||||
| 96 |
Your Factors
Set these from your own welder logs. The defaults are planning numbers, an instruction to replace, not a standard to defend.
Material and Wall Multipliers
Take the Worksheet With You
Download this run as a PDF worksheet: your lines, your factors, the math shown per line, plus a blank version you can reuse on the next bid.
The arithmetic runs in your browser · nothing on this page is stored or sent anywhere
How the Math Works
A dia-inch is nominal pipe size times the number of butt welds. Ten welds on 6 inch pipe is 60 dia-inches. It is the oldest unit in piping labor pricing because it scales with weld length the way hours actually do.
Hours round to the nearest 10 and dollars to the nearest $1,000, because the inputs are estimates and precision on an estimate is a lie. Dia-inch counts stay exact, those were counted.
Where the Defaults Come From
The defaults are common planning ranges for process piping, tuned conservative. They exist so the page works on first load. Your welder logs outrank them the moment you have them.
| Factor | Default | Common Range |
|---|---|---|
| Shop MH per dia-inch, CS std wall | 0.75 | 0.5 to 1.0 |
| Field multiplier | 2.0 | 1.5 to 2.5 |
| Stainless multiplier | 1.35 | 1.2 to 1.5 |
| Heavy wall multiplier | 1.5 | 1.3 to 1.8 |
Why the Real Number Is Larger
Two layers sit on top of the weld hours this page prices. Fit-up and handling usually add 30 to 60 percent of weld time on field-heavy work, and it lands before an arc is ever struck. Repair rework on alloy and heavy wall adds again, and it compounds, because a cut-out is a new joint at the same dia-inches.
Carry both as their own line items. Burying them inside a fatter weld factor is how a bid stops being auditable.
Where theTakeoff.ai Fits
This calculator prices the welds after you have counted them. The counting is the slow part. theTakeoff.ai reads your P&IDs and isometrics, counts the joints, and lets you click any number to see the exact spot on the drawing it came from.
See It on Your Own Drawings →FAQ
Does my data leave this page?
The math runs in your browser. Nothing is stored or sent anywhere unless you ask for the worksheet, and then we get only the details you type into that form.
What about socket welds and olets?
Most desks carry small-bore socket work as a separate factored line rather than folding it into butt-weld dia-inches. This page follows that convention and counts butt welds only.
Why nominal size and not actual OD?
Convention. Dia-inch factors are built against NPS, so switching to OD without rebuilding the factors would move every number for no gain in accuracy.
Can I use my own labor standard?
Yes, that is the point. Overwrite the base factor and the multipliers with your own history and the page becomes your standard with the arithmetic done for you.
Dia-inches are computed as NPS times butt-weld count per line. Default factors are editable planning values, not a published labor standard, and no output on this page should be bid without checking the factors against your own job history.