The Builder’s ToolkitFree UK building calculators
Free UK timber purchasing tool

Timber Length Calculator

Turn the linear metres from your cutting list into whole stock lengths using the exact length your merchant actually sells.

Actual supplier stock length0% extra by defaultWhole-length rounding
Timber lengths and cutting-list illustration

Convert linear metres into stock lengths

Start with the total timber length already required by your measured cutting list. Then enter the stock length for the exact section and grade you intend to buy.

m
Net linear metres from your measured cutting list before any optional extra.
m
Enter the actual purchasable length for the timber section/grade you are ordering.
%
Optional extra only. There is no universal timber-waste percentage, so 0% is the neutral default.
Important: this is a linear-metre purchasing check, not a cut optimiser. If your cutting list contains individual pieces, joints are restricted, or offcuts cannot be reused, plan those cuts separately.
Enter your required linear metres and the merchant's stock length.The calculator will keep the net requirement, optional extra and commercial whole-length rounding separate.

How to calculate how many timber lengths to buy

This calculator deliberately starts after you have measured the job and prepared a timber take-off or cutting list. Add the required piece lengths to get a net linear-metre total, then use the actual stock length offered for the exact timber section you are buying.

1. Total the required cuts

Add the measured lengths your job needs. Keep different timber sections or grades as separate calculations.

2. Check the merchant length

Stock length varies by section, treatment, grade and supplier. Enter the length actually available to you.

3. Round commercially

The adjusted linear requirement is divided by stock length and rounded up to the next whole purchasable piece.

Base stock lengths = required linear metres ÷ supplier stock length, rounded up.

Optional extra is applied to the linear-metre target first. It is not built into the calculator as a fixed waste assumption.

Why there is no default timber stock length

Current UK merchants sell construction timber in several lengths. Wickes' current C16 range includes 2.4 m, 3.0 m, 3.6 m and 4.8 m options, while current Travis Perkins listings include 3.0 m, 3.6 m, 4.2 m, 4.8 m and other lengths depending on section. That makes a fixed 4.8 m assumption unsuitable for a general timber calculator.

Current merchant checks: Wickes treated C16 timber range and representative Travis Perkins 3.0 m C24 / 3.6 m C24 listings. Availability can vary by branch and timber section, so use the stock length for your actual order.

Worked timber-length example

Suppose your cutting list totals 35.00 m and your chosen timber is available in 4.80 m lengths.

At the neutral 0% extra setting: 35 ÷ 4.8 = 7.292, so you need 8 whole stock lengths. Those lengths contain 38.40 m nominally, leaving 3.40 m above the linear-metre target before considering the actual cutting pattern.

If you deliberately choose 10% extra, the adjusted target becomes 38.50 m and rounds to 9 whole 4.8 m lengths.

Linear metres are not the same as a cutting plan

Two jobs can have the same total linear metres but need different numbers of stock lengths. For example, three required pieces at 3.0 m each total 9.0 m. Simple division by 4.8 m suggests two lengths contain enough timber overall, but each 3.0 m piece needs its own stock length because two 3.0 m cuts cannot come from one 4.8 m piece. Use this calculator as a purchasing cross-check only when the linear-metre approach is appropriate.

Quantity tool, not structural design. This calculator does not choose timber section, species, strength grade, treatment class, span, joint location or structural suitability. Follow the drawings/specification and buy the specified material.

Useful next steps

If you are pricing trim rather than general timber, use the Skirting Board Calculator. For a framed partition use the Stud Wall Materials Calculator. For a deck, keep surface boards and joists separate with the Decking Board Calculator and Decking Joist Calculator. See Linear Metres Explained for the measurement principle.

Common timber estimating mistakes

  • Assuming every merchant sells the same stock length.
  • Adding a generic waste percentage before checking the real cutting pattern.
  • Combining different timber sections or grades into one linear total.
  • Treating total linear metres as proof that every individual required cut fits the selected stock length.
  • Rounding the stock-length quantity down.

Frequently asked questions

Should I automatically add 10% waste?

No. Extra timber depends on the cutting list, defect selection, joint rules, repeat lengths and whether offcuts can be reused. Start at 0%, then add only the extra you deliberately want to order.

Can I use this for structural timber?

You can use it to convert an already specified structural-timber linear requirement into stock lengths. It does not select joist, stud or rafter sizes and does not verify structural adequacy.

Why can a cut list need more pieces than this result?

The calculator divides total linear metres by stock length. Individual long cuts may not nest efficiently within those lengths. A true cut optimiser needs every individual required piece length.