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.
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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, the PDF and the full-size template, no card needed. Full access, with DXF: £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 (Auger Flight)
- Square to Round
- Inclined Square to Round
- Pipe Coping (Branch / Tee)
- Rectangular Transition
- Eccentric Square to Round
- Discharge Chute
- Angle Cut Cone
- Cylinder with Branch Hole
- Rectangular Duct Bend
- Y Piece Trunk (Breeches)
- Y Piece Leg (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
- Spur Gear
- Tapered Screw Flight
- Rectangular Duct S-Offset
- Rectangular Duct Wye
- Plenum Box with End Cap
- Starting Collar (Round Takeoff)
- Offset Rectangular Transition
- Reinforcing Pad
- Square to Round on Pipe
- Segmented Round S-Offset
- Pipe on a Bend (Dummy Leg)
- Plate with Hole for an Angled Pipe
- Pipe-to-Cone Elbow
- Bent Profile (Angle, Channel, Z and Hat)
- Sheet Metal Box (Tray)
- Dished Head in Petals (Torispherical and 2:1)
- Spiral Staircase
- Square Tube V-Notch Bend
- Square Tube Miter
- Centrifugal Fan Scroll
- Toriconical Cone (with Knuckle)
- Header (Shell with Several Branch Holes)
- Angle Iron V-Notch Bend
- Polygon to Round (Hexagon, Octagon)
- 3D Sheet Metal Barn Star
- Box Section T Joint
- Triple Wye (Three-Leg Breeches)
- Rolled Tube Arch
- Conduit Bending (EMT)
- Angle Ring (Rolled Angle Iron)
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
- Bend allowance and K-factor calculator, and the neutral axis: why every development uses D − t
- 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
- Plate 'n' Sheet alternative: Planichapa develops sheet metal parts in the browser, with the price on the page
- How to lay out a mitre-cut pipe: paper template, sine wave and ordinate table
- LITIO alternative: Planichapa develops sheet metal parts in the browser, nothing to install, now that LITIO2 is no longer sold
- Pipe ovality: a calculator, the formula, a worked example, the limits the codes use and how to measure it in the shop
- Steel plate and sheet metal weight calculator: weight per m² and ft², gauges and stock plate sizes
- Sheet metal gauge chart: gauge to inches and mm for steel, galvanized, stainless and aluminum
- 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 end cap, the collar and the transitions
- Smoker stack and firebox templates: the cuts where pipe meets the cook chamber, in inches
- Laser and plasma cutting cost calculator: the formula, a worked example and how to measure the cut length
- Tank volume calculator and strapping chart: horizontal and vertical tanks with 2:1, torispherical, hemispherical or flat heads
- Merge collector template generator: a printable cutting template for 2, 3, 4, 6 or 8 into 1
- Dome template generator: printable gores for a dome or a hemisphere in paper, EVA foam or sheet metal
- DIY cyclone dust collector plans: every sheet of the cyclone from the Stairmand proportions, for any duct size
- Cable tray bend: how to make vertical and horizontal 90 and 45 degree bends with a V notch
- Sheet metal nesting online
Frequently asked questions
Is Planichapa free?
Yes. Unlimited calculations, with the drawing, the 3D view, PDF export, the full-size 1:1 template and saved history, with no ads. DXF export 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. DXF export is part of full access; the PDF and the full-size template are free.
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.