UK and Ireland
Metres by default- 400 mm stud and joist centres, metric sheets
- Ground screws or concrete pads under garden rooms
- Flush beams on decks, slotted concrete fence posts
- Feather edge, cedar, composite and slatted cladding
Free in your browser · no sign-up
Your garden room in 3D, with the exact materials to buy.
Enter the size. Get the frame, sheets, cladding, roof, insulation and base, worked to UK, Irish, US or Canadian practice.
- Works on your phone
- Summary PDF free
- Metres or feet
- No invented prices
Live 3D modelGarden room calculator
How it works
From a measurement to a build-ready pack.
The first two steps are free and need no account. Pay only when you want the pages you cut and build from.
- Free
Step 1
Enter the size
Width, length and height in metres or feet. Pick your country and its building practice follows.
- Free
Step 2
See it in 3D and check every number
Frame, sheets, cladding, roof, base and fixings, each with the rule it came from.
- $9
Step 3
Get the pack you build from
Cut list in stock lengths, the diagonal to square the frame, yard sheet and build order.
Start from a popular style
Six garden rooms people actually build.
Pick a style in the calculator, then change the size, roof, doors, windows or cladding. The 3D and the material list follow every change. In the US and Canada the styles switch to local materials.
Most popularContemporary studioVertical slats · parapet · sliding glassTraditionalClassic garden lodgeFeather edge · apex · French doorsWork from homeGarden officeComposite · mono-pitch · desk windowLight and openSummer houseSlats · canopy · bi-fold doorsBudgetSeasonal roomSheet cladding · apex · uninsulatedStorage and toolsWorkshop & storeSheet cladding · mono-pitch · high window
Built the local way
Your country's materials, not someone else's.
Pick your country and the tools switch to the stock sizes and build methods used there. Materials from different regions never mix in one list.
US and Canada
Feet and inches by default- 16 in centres, 4 × 8 ft sheets, nominal lumber
- Concrete footings taken below the frost line
- Drop beams on decks, cable or baluster railing
- Lap siding, board and batten and cedar
A take-off to local building practice, not a structural design or a building-control approval.
Choose the job
A focused tool for each structure.
Each tool asks only for what matters to that structure, and returns a material list you can inspect.
Most used
Garden room calculator
Size a garden room shell and count the frame, sheets, cladding, roof, insulation and base materials.
3D shell · full take-off · summary PDF
Calculate my garden roomDeck tool
Deck + pergola designer
Set the footprint, height, boards, railings, stairs and pergola. See the model update, then check framing and quantities.
3D model · full take-off · summary PDF
Calculate my deckFree calculator
Fence calculator
Lay out a fence run and calculate panels, posts, rails, boards, concrete and fixings from its actual length.
3D view · full take-off · summary PDF
Calculate my fenceWhy it matters
A nice 3D picture is not a shopping list.
Most free planners stop at the picture, and some only count their own brand's boards. The merchant still asks how many studs, which sheets and how much cladding. Here is the same 4 m × 3 m garden room both ways.
A render on its own
- A picture of the room
- The floor area: 12 m²
- Materials guessed from the area, if at all
- No frame, no sheets, no roof build-up, no fixings
You still have to work out the structure before you can order anything.
BuildPlot3D take-off
- Floor area
- 12 m²
- Frame studs
- 48 × 2.67 m
- Sheets (floor, walls, roof)
- 23
- Cladding boards
- 247 incl. 10% waste
- Insulation packs
- 11
Plus roof covering, base and fixings, with the rule behind each number shown. Inspect it free; get the order-ready files in the complete pack.
Numbers above are worked out live by the same take-off the calculator uses (UK practice, Vertical timber slats). It is a take-off, not a structural design.
Get the list for your garden roomFree vs the pack
Use the tool for free. Pay once for the pages you build from.
The list tells you what to buy. The pack tells you how to cut it and put it together.
Free
$0No account needed. A free account keeps 25 jobs.
- The 3D drawing and the full take-off to inspect on screen
- A PDF summary with the design, overall measurements and checks
- Your own supplier prices, on any plan
Full Build Pack
$9 per jobOne payment. No subscription. Kept for good.
- Dimensioned framing plan and the exact cut list, packed into stock lengths
- CSV merchant order file, ready for a supplier or spreadsheet
- Setting out: the diagonal to pull so the frame is square before anything is fixed
- Yard order sheet: only things a merchant can hand over, each line checked and in your own units, with a box to tick
- Build order: each stage in sequence, with the check that goes with it
- Your company name on the PDF and the shared page, with our line gone
Doing this every week? Plans from $19/mo
Built to be checked
Clear inputs, visible assumptions.
The free tools work without an account
Draw the structure, inspect the full take-off on screen and save a summary PDF. Create an account only when you want to save your work.
Designed for a phone screen
Change measurements and inspect the model while you are standing where the structure will go. There is no app to install.
Quantities are not tied to a timber brand
There is no merchant catalogue or affiliate basket. Costs appear only from the supplier rates you enter yourself, on any plan.
Assumptions are visible
See the spacing, waste allowance, stock lengths and regional source used for each result. L and U layouts update the frame and perimeter calculations too.
Material take-off
Quantities, cut lengths, stock and fixings before ordering.
Full Build Pack
Dimensioned plan, cut list, order file and site sequence.
Regional setup
UK, Irish, US or Canadian practice, in metres or feet.
Saved jobs
A free account keeps 25 jobs with your own rates.
Quick calculators
One question at a time.
If you only need one answer, start here. Open the full designer when you need the 3D model and complete list.
Garden room calculator
Frame, sheets, cladding, roof, insulation and base for the shell.
Decking calculator
How many decking boards a given area needs, with the frame under it.
Composite decking calculator
Board counts and fixings for composite boards and hidden clips.
Deck stairs calculator
Equal step rise, going, treads and stringers for the drop to the ground.
Fence calculator
Panels, posts, rails, gravel boards and concrete for a fence run.
No false precision
What BuildPlot3D does not pretend to know.
Your supplier prices.Costs remain blank until you enter the rates you actually pay.
The final structural answer.The tools help with planning and take-offs; they do not replace a structural check or local approval.
The exact final order.Site conditions and supplier stock can change what is needed, so review it before purchase.
A survey of your ground.The model assumes level ground; slopes, drainage and obstructions still need measuring on site.
See how builders can use it Common questions
What to know before you start.
Does it work on a phone?+
Yes. The designer, the 3D model and the take-off are built for a phone first, so you can change measurements on site. No app to install.
Which board length wastes least?+
The designer compares common stock lengths for the country you pick and shows the offcut percentage for each. You can then choose the option that suits the job.
What can I do without an account?+
You can use the designer, inspect the 3D model and full material take-off, and export a summary PDF. The merchant CSV, dimensioned plan and exact cut list come with a job pack or paid plan. An account is only needed to save designs and use account features.
Are the prices supplied by BuildPlot3D?+
No. Material and labour prices vary by supplier and account. Costs appear only after you enter your own rates; BuildPlot3D does not insert national averages or invented prices.
What is on the yard order sheet?+
Only things a merchant can hand over: boards, timber, posts, concrete, sheets and fixings, in metres or feet to match your job. Every line is checked before the pack prints, so there are no zero lines, repeats or mixed units. It comes with a one-off job pack or any paid plan, for decks, fences and garden rooms.
Is this a structural design or final quote?+
No. It is a planning and material take-off aid. Check the structure, local requirements and final order before construction.
No account required