Spoolset
A pipefitter's offset calculator. Offsets, rolling offsets and grade — in feet-inch-fractions, with a drawing that redraws as you type.
One-time purchase. No subscription, no ads, no accounts.
What it looks like
What it does
Simple offset
Offset and fitting angle in, travel and run out. 11¼°, 22½°, 30°, 45°, 60°, 90°.
Grade & fall
Rise over run as a percentage and as inches per foot. ¼" per foot is 2.08%.
Rolling offsets
Set and roll in — true offset, travel, and the roll angle to turn the fitting to.
Take-outs
Cut length with both fittings subtracted. ASME B16.9 elbows, and you can measure your own and save it.
Pipe data
Steel schedule 40 and 80 — outside diameter, wall thickness, inside diameter.
The drawing
Every mode draws what you typed, in every mode, free or not. A wrong input shows up as a wrong shape before it becomes a wrong cut.
Where the numbers come from
A wrong take-out is a wasted length of pipe, so the arithmetic is not taken on trust.
- The geometry is checked against itself. Alongside the usual test vectors, every offset is rebuilt as three-dimensional coordinates and measured — no trigonometry involved — so the check cannot share a wrong assumption with the formula it is checking.
- Take-outs are a published table, not a formula. ASME B16.9 long-radius elbows, cross-checked against two independent references. The formula they replaced was wrong by a factor of two on a ½" 45° elbow.
- Where no standard exists, it says so. B16.9 lists 45° and 90° only. At 11¼°, 22½°, 30° and 60° the app marks the figure approximate and lets you measure the fitting in your hand and save that instead.
- Every table names its source in the app, on the Settings screen.
- The geometry itself is not a secret: every formula the app uses is written out here, with worked examples and the B16.9 take-out table, so you can check any number by hand.
Built for the job, not the desk
- Works with no signal. No accounts, no servers, no sign-in. Nothing to lose in a plant room or a crawlspace.
- Feet-inch-fractions. Type
12'6-3/8"the way you write it. Millimetres if you prefer. - Glove-sized keys, with a fraction key and a proper backspace — not a clear-all.
- VoiceOver and large text. Every dimension is spoken properly, and the whole app scales to the largest accessibility text size without cropping a number.
How it is sold
No subscription. A single one-time purchase unlocks the paid features.
No account, no sign-in, no email required.
No ads, no tracking, no analytics. The app makes no network requests at all. See the privacy policy — it is short.
Support
Something wrong, confusing, or missing? Email support@spoolset.app.
If a number looks wrong, that is the one thing worth interrupting anyone for — include the inputs you used, the fitting size and angle, and what you expected. If a take-out disagrees with the fitting in your hand, say which fitting and which standard it came from.
It is one person answering, so replies are not instant, but every message is read.