Project tools

Cladding Estimator

Built for UK makers in millimetres. Measure one wall, say how many walls are the same size, and get a board count you can take to the merchant.

Related guides Species data

All numbers are live. This counts the same wall, repeated. If two walls differ, run the job twice or share each one.

Quick start

Measure one typical wall in millimetres — width and height.
Say how many walls are that same size. Different walls need another pass.
Pick the profile you are actually buying. Feather edge uses your overlap; shiplap and T&G use the pack cover if you type it, otherwise a typical machined cover. Square-edge open joint adds the gap.
Leave batten centres at 600 mm unless your specifier asked for closer.
Add one window or door if you want it taken off, then copy the list.

What each thing means

Same-size walls: The tool multiplies one rectangle. Four identical shed walls is four. A long side and a gable are two separate jobs.
Effective cover: How far each course climbs the wall. Feather edge is width minus overlap. Shiplap and tongue-and-groove use the pack figure if you type it, otherwise a typical UK machined face. Square-edge open joint adds the joint to the board — a 125 mm board with a 10 mm gap occupies 135 mm, not 115.
Batten centres: 600 mm is the usual UK spacing. Fixings are counted as nails or screws per board at each batten, then multiplied by the battens on the wall.
One opening: Width × height of one window or door, taken off the whole job. Add several together if you have more than one.
Waste: Applied once to the running board count — not piled on top of a board rounded up at every row. Raise it for lots of corners and cuts.

Your walls

One typical rectangle

Measure one wall. The count then repeats that wall — it does not invent a different elevation for each side.

Wall width (mm)Across the face you are cladding.Wall height (mm)From the first board to the last course.Walls that sizeSame rectangle, counted together.Waste (%)Applied once, after the running count.

The boards

Profile changes the cover

Feather edge uses the overlap you type. Shiplap and tongue-and-groove use the cover on the pack if you type it, or a typical seated cover if you leave that blank. Square-edge open joint adds the joint to the board width.

Board width as sold (mm)The nominal width on the rack — 125 mm is a common UK pack.Board lengthLonger packs mean fewer butt joints across the wall.Overlap (mm)How much each feather-edge board sits over the one below.

If the ticket says waney or green oak, start the overlap around 50 mm and average the widths in the pack — or run the job twice. Widths vary.

Battens and an opening

Fixings follow the battens

One nail through the thick edge, just clear of the board below — usual UK feather-edge practice. 600 mm centres is the usual UK starting point.

Batten centres (mm)How far apart the battens sit. Closer centres mean more battens and more nails.

Fixings on this job

1 per board at each batten

8 battens on each wall

Opening width (mm)Optional. Leave at 0 if you will deduct windows yourself.Opening height (mm)One window or door, taken off the whole job.

What to order

Boards

176

Order 176 × 125 mm feather edge boards, 2400 mm long, for 4 same-size walls.

24 rows × 1.67 boards per row × 4 walls + 10% waste → 176 boards

Effective cover

100 mm

Each course advances 100 mm — the board width minus the overlap you chose.

Wall area

38.40 m²

Linear metres

422.4 m

Battens

32 @ 600 mm

Fixings

845

This is a shopping estimate, not a certificate.

Take this with you

Copy the list, share the job, or print a sheet for the merchant.

What to buy

176 × 125 mm feather edge boards, 2400 mm long (422.4 linear metres)
32 × battens at 600 mm centres, cut to about 2400 mm (the wall height)
About 845 nails or screws (1 per board at each batten, plus 10% spare)

In plain English

You have 4 walls of that size: each 4000 mm wide × 2400 mm high.
Feather edge: 125 mm board − 25 mm overlap = 100 mm cover.
Boards run across the wall. 24 rows × 1.67 boards per row × 4 walls + 10% waste → 176 boards
Battens at 600 mm centres: 8 on each wall, 32 in total.
Fixings: 1 per board at each batten — 845 with 10% spare. One nail through the thick edge, just clear of the board below — usual UK feather-edge practice.

Useful Mill & Merchant reading

Read before you order

A few timber lessons that sit behind a clad wall that stays on.

Buying timber before you build

Moisture, flatness, and what to check at the rack before you load the van.

Designing for wood movement

Why a cladding board still needs room to move once it is on the wall.

Cladding a garden room

Membrane, battens, cavity, and the details that last longer than the first summer.

Get better results

Boards are assumed to run across the wall. For vertical cladding, swap width and height in your head and run it again.
10% waste is a fair shed or garden-room start. Go higher around windows, doors, and barges.
Stainless outdoors, especially on cedar and anything near the coast.
Buy the last pack unopened if you are hovering near a full bundle — easier to take back than to scramble mid-job.

Reading the numbers

The big number is what to order. The working line is rows × boards per row × walls, plus waste. Cover or pitch sits next to that number so you can see why feather edge, T&G, and open joint do not buy the same.

Not a substitute for structural sign-off

This is a shopping estimate, not a certificate. It does not size cavities, membranes, flashings, or wind loads. Confirm the cover width on the pack you actually buy.

Quick start

Measure one typical wall in millimetres — width and height.
Say how many walls are that same size. Different walls need another pass.
Pick the profile you are actually buying. Feather edge uses your overlap; shiplap and T&G use the pack cover if you type it, otherwise a typical machined cover. Square-edge open joint adds the gap.
Leave batten centres at 600 mm unless your specifier asked for closer.
Add one window or door if you want it taken off, then copy the list.

What each thing means

Same-size walls: The tool multiplies one rectangle. Four identical shed walls is four. A long side and a gable are two separate jobs.
Effective cover: How far each course climbs the wall. Feather edge is width minus overlap. Shiplap and tongue-and-groove use the pack figure if you type it, otherwise a typical UK machined face. Square-edge open joint adds the joint to the board — a 125 mm board with a 10 mm gap occupies 135 mm, not 115.
Batten centres: 600 mm is the usual UK spacing. Fixings are counted as nails or screws per board at each batten, then multiplied by the battens on the wall.
One opening: Width × height of one window or door, taken off the whole job. Add several together if you have more than one.
Waste: Applied once to the running board count — not piled on top of a board rounded up at every row. Raise it for lots of corners and cuts.

Order 176 × 125 mm feather edge boards, 2400 mm long, for 4 same-size walls.

Mill & Merchant — Cladding estimator

Order 176 × 125 mm feather edge boards, 2400 mm long, for 4 same-size walls.

The job
  You have 4 walls of that size: each 4000 mm wide × 2400 mm high.
  Feather edge: 125 mm board − 25 mm overlap = 100 mm cover.
  Boards run across the wall. 24 rows × 1.67 boards per row × 4 walls + 10% waste → 176 boards
  Battens at 600 mm centres: 8 on each wall, 32 in total.
  Fixings: 1 per board at each batten — 845 with 10% spare. One nail through the thick edge, just clear of the board below — usual UK feather-edge practice.

Working: 24 rows × 1.67 boards per row × 4 walls + 10% waste → 176 boards
Effective cover: 100 mm. Each course advances 100 mm — the board width minus the overlap you chose.
Wall area: 38.40 m²

What to order
  176 × 125 mm feather edge boards, 2400 mm long (422.4 linear metres)
  32 × battens at 600 mm centres, cut to about 2400 mm (the wall height)
  About 845 nails or screws (1 per board at each batten, plus 10% spare)

This is a shopping estimate, not a certificate.