Create accurate flat patterns
for pipes, cones, transitions and branches
Preview your part in 3D and export production-ready DXF files for plasma, laser and oxy-fuel cutting.
How sheet metal development works here
Choose a part
We develop new parts constantly!
Enter measurements
In millimetres or inches: pick one with the switch above the form.
See and place dimensions on your results
You can also export to CAD or print to PDF
Free: unlimited calculations and 1 part a month in DXF, no card needed. Full access: £9 for 1 month, or £69 for 12 months, one-off. See pricing
Pattern development for pipe fabrication
Each part has a page covering what it is, which measurements the calculation needs and a worked example — from cones and transitions to branches and segmented bends.
- Cylinder
- Cone
- Oblique Cone
- Offset Cone
- Chinese Hat
- Truncated Cylinder
- Double Cut Cylinder
- Segmented Bend
- 90° Segmented Bend
- 180° Segmented Bend
- Elbow
- Pipe Offset (Portal)
- Elliptical Tube
- Oval Tube
- Screw Flight (Helicoid)
- Square to Round
- Inclined Square to Round
- Pipe Branch (Tee)
- Rectangular Transition
- Eccentric Rectangle to Round
- Discharge Chute
- Angle Cut Cone
- Cylinder with Branch Hole
- Rectangular Duct Bend
- Y Piece Trunk (Breeches)
- 4-Way Cross Shell
- Sphere Gore (Dished Head Petal)
- Round to Oval
- Truncated Rectangular Tube
- Cone Branch
- Cone with Branch Hole
- Offset Pipe Branch (Tangential Inlet)
- Rectangular Tap on Pipe
- Cylinder with Rectangular Hole
- Conical Tap (Conical Tee)
- Tapered Segmented Bend
- Cylinder with Conical Branch Hole
- Angular Boot, Rectangle to Round
- Parallel-Axis Nozzle on a Cone
- Cone with Parallel-Axis Nozzle Hole
- Obround to Rectangle
- Regular Pyramid Frustum
- Rectangular Tap on a Cone
- Cone with Rectangular Hole
- Nozzle on a Spherical Head
- Conical Tap on Cone
- Cone with Conical Tap Hole
- Oval Segmented Bend
- Oval to Oval Reducer
- Conical Y Piece (Tapered Breeches)
- Flange
- Chain Sprocket
Development guides
- How to develop a cone (frustum) in sheet metal: formula, sector radii and angle, step by step
- Lobster back bend calculator (segmented 90° elbow): gore angles, cut heights and how many plates
- Pipe saddle calculator and development: how to lay out a pipe-to-pipe branch (tee) at 90 and 45 degrees
- Square to round transition: development by triangulation, step by step
- The neutral axis of plate: why every development uses D − t, and the bend deduction
- Sheet metal glossary: the terms of marking out and pattern development in plate fabrication
- How we check the Planichapa calculations, and who is behind them
- LITIO alternative: Planichapa develops sheet metal parts in the browser, nothing to install, now that LITIO2 is no longer sold
- How to lay out a mitre-cut pipe: paper template, sine wave and ordinate table
- Plate 'n' Sheet alternative: Planichapa develops sheet metal parts in the browser, with the price on the page
- Steel plate weight calculator, weight per m², gauges and stock plate sizes: table and formula
- Pipe ovality: a calculator, the formula, a worked example, the limits the codes use and how to measure it in the shop
- Sheet metal pattern development software: how to choose, and what changes between a desktop program, a phone app and an online calculator
- Eccentric and concentric reducers: which one to use and how each one develops on plate
- Roller chain size chart: ANSI, ISO 606, motorcycle and bicycle chain pitch and roller diameter
- Sprocket dimensions: pitch diameter, outside and root diameter, tooth form and a pitch diameter chart
- Bolt circle layout: the position of each hole, the chord between holes and a chord chart
- Chain length and sprocket ratio: the formulas, a worked example and how many links to cut
- Screw flight calculator: the flat blank of a screw conveyor flight (auger), with the formula and a worked example
- Plate rolling calculator: the blank length of a rolled shell, with the formula, a chart and a worked example
- Tube notching template generator: a printable coping template for any tube, angle and offset
- Dished head calculator: depth, volume, blank diameter and weight of torispherical, 2:1 elliptical and hemispherical heads
- Cone template generator: a printable full-size cone template for hoppers, funnels and reducers
- Pie cut calculator for exhaust and tube bends: saw angle, pie lengths and a wrap-around template
- Duct transition layout: square to round duct, centred, offset or flat on one side
- Pipe template, printable at full size: tee saddle, 45° lateral and mitre cut for every pipe size from NPS 1/2 to 12
- Register boot layout: from a floor, wall or ceiling register to a round duct, in inches
- Plenum box and plenum transition layout: the sides, the offset and the round outlet
Frequently asked questions
Is Planichapa free?
Yes. Unlimited calculations, with the drawing, the 3D view, PDF export, the full-size 1:1 template, saved history and 1 part a month in DXF, with no ads. Unlimited DXF is part of full access.
Do I need an account to see the parts?
No. The part list and the page for each part are open, and every part calculates on its own page with no account. The account comes in when you export or save, because that is what goes into your history.
Does sheet thickness affect the result?
It does. Every development is calculated on the neutral axis, at mid-thickness, where the sheet neither stretches nor compresses as it is formed. That is why a can's blank length is π times the mean diameter, not the outside one.
Can I take the drawing to a cutting table?
Yes. DXF export writes the outline as lines and arcs, which is what plasma, laser and oxy-fuel tables read. A free account exports 1 part a month in DXF; full access exports without limits.
What units do I enter?
Millimetres or inches. Pick one with the mm | inches switch above the form, and the whole result follows: the drawing, the measurements table, the printed sheet and the DXF.