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Wood screws buying guide

Updated: October 2026

You have a Pozidriv bit in the drill and a joint in front of you, and the packet is speaking two languages at once. One line says 4.0 x 30 mm. Another says No. 8. The screws are yellow, which looks like a rust rating and is only a plating colour. This wood screws buying guide puts the checks in order: the joint, the letters on the recess, the millimetres, the thread, then the finish. The piece count comes last. The examples are the boxes on the [wood screws comparison](/hub/screws-and-accessories/wood-screws). Figures are amazon.co.uk shelf prices from 15 October 2026. Products Compared did not run a lab test. A qualifying purchase can earn a commission at no extra cost to you.

You have a Pozidriv bit in the drill and a joint in front of you, and the packet is speaking two languages at once. One line says 4.0 x 30 mm. Another says No. 8.

Our top picks

TIMCO TIMCO Index 6.7 x 150 mm, box of 50

Best overall

TIMCO TIMCO Index 6.7 x 150 mm, box of 50
8.5/10about £13.55
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ForgeFix ForgeFix 4.0 x 30 mm, box of 200

Best value

ForgeFix ForgeFix 4.0 x 30 mm, box of 200
7.8/10about £2.03
View offer
TIMCO TIMCO Solo 5.0 x 100 mm, box of 100

Rank 3

TIMCO TIMCO Solo 5.0 x 100 mm, box of 100
9.0/10about £4.19
View offer
On this page
  1. 1.Match the screw to one joint
  2. 2.Drive, millimetres, thread
  3. 3.Finish is not the colour
  4. 4.What these boxes actually are

Match the screw to one joint

Start with the two pieces of timber, not the fullest organiser. A repeated joint wants one diameter and one length. A mix is useful only if its longest screw is longer than the top piece. The TIMCO Index 6.7 x 150 mm hex screw is a landscaping fastener, a poor stand-in for a 4.0 x 30 mm carcass screw. The short yellow box is a poor stand-in for a sleeper. B&Q describes a traditional woodscrew as a smoother shank that wants a pilot and a clearance hole. The yellow Pozi boxes are chipboard screws: a sharp point, a coarse thread, a double-countersunk head. A 4.0 x 30 mm screw can pass a 15 mm back. In an 18 mm top on a 45 mm rail it leaves almost nothing in the second piece. Lengths for a repeated joint are on the best wood screws page.

Drive, millimetres, thread

PZ is Pozidriv, PH is Phillips, and a hex head is a socket. Pozidriv has extra ribs so the driver stays seated. Phillips is built to cam out, and bolts.co.uk says not to mix the bits. Gorffy and Flintronic print Phillips. Most other boxes print Pozidriv. ForgeFast says Torx in one field and Pozi in the bullets, so you check the recess. The tick marks are on the Pozidriv and Phillips page. A countersunk length runs from the point to the flush head. Screwsline maps No. 8 to 4.0 mm, No. 6 to 3.5 mm and No. 10 to 5.0 mm. Olympic Fixings prints about 4.17 mm for 8 gauge. Full thread grips in chipboard and in a plug. Partial thread pulls the top piece tight. Solo says 70 mm of thread from 80 mm up, so the 5.0 x 100 mm box is partial. The ForgeFix single sizes are fully threaded. Pilot and clutch are on the how to use wood screws page.
TIMCO TIMCO Index 6.7 x 150 mm, box of 50

Testsieger

TIMCO TIMCO Index 6.7 x 150 mm, box of 50
8.5/10about £13.55
View offer

Finish is not the colour

Yellow, gold and bright zinc are plating colours. BuildWiz describes yellow zinc as an interior finish. None of these listings states BS EN 14592 or UKCA, and this comparison has no stainless ASIN. TIMCO publishes salt-spray hours elsewhere, but they are not printed on the Solo or Index listings here. Green oak and cedar want a grade the maker rates for that place. A4 is the grade TIMCO points at heavier salt. A deck or a sleeper is not a yellow-box job. The outdoor-shaped screw here is the green hex Index, with no structural mark on the listing.

What these boxes actually are

Sort by the longest screw, not the star line. Gorffy and Flintronic stop at 40 mm. Heifix 200 stops at 60 mm. Heifix 800 reaches 5.0 x 100 mm, 20 pieces. The ForgeFix organiser title says 1,000 while the bullet counts add to 1,500. ForgeFix sells 4.0 x 30 mm at £2.03, 3.5 x 40 mm at £2.40 and 5.0 x 40 mm at £3.84. Solo 5.0 x 100 mm is £4.19, ForgeFast 5.0 x 80 mm is £5.83 and Index 6.7 x 150 mm is £13.55. Brackit claims 16 mm to 80 mm against a piece field of 780.

Common questions

Do I buy one size or a mixed box?
Buy one size when you know the joint and will repeat it. A box of 200 at one size is cheaper per screw than fishing that length from an organiser. Buy a mix only when the longest screw is still long enough for the thickest top piece you own. A 40 mm maximum cannot do a 100 mm joint.
What does No. 8 mean in millimetres?
On Screwsline’s trade table, 8 gauge maps to 4.0 mm, 6 gauge to 3.5 mm and 10 gauge to 5.0 mm. Olympic Fixings prints a finer figure, about 4.17 mm for 8 gauge. Current packets are usually metric and may show a gauge only as a shorthand. Read the millimetres on your box and treat the gauge map as a translation, not as a second size hiding in the same screw.
Is a chipboard screw the same as a woodscrew?
They overlap in shop language, and they are not the same fastener. B&Q says a traditional woodscrew wants a pilot and a clearance hole. A chipboard screw is the yellow Pozi pattern: sharp point, coarse thread, double-countersunk head. Solo’s long lengths are partial thread. Read the thread line on the packet you are holding.
Does a full thread or a shank pull two pieces together?
A full thread grips in both pieces, which suits chipboard and plugs. A smooth shank or a partial thread lets the head draw the top piece down. Solo’s rule is 70 mm of thread from 80 mm up, so a 100 mm Solo screw has a plain section. A fully threaded 40 mm ForgeFix screw does not.
How is the length of a countersunk screw measured?
Measure a countersunk screw from the point to the top of the head. That is the convention on bolts.co.uk and in the Interdiy guide. A hex flange is often measured under the head, so a 150 mm Index screw is not using the same picture as a 40 mm countersunk screw. The listing does not say which convention it used.

Related pages

Screws and accessories

Wood screws

Best wood screws: the box to open for indoor joints

Decking and sleeper screws: leave yellow zinc indoors

How to use wood screws without splitting the timber

Pozidriv vs Phillips: which bit seats in the screw

Sources

Public UK sources on timber fasteners, UKCA, recess types, gauges and stainless grades. Listing prices and star counts are from the amazon.co.uk extracts kept for this comparison on 15 October 2026. Prices move.

  1. BSI, BS EN 14592:2022 (retrieved 15 October 2026)
  2. GOV.UK, designated standards for construction products (retrieved 15 October 2026)
  3. Fastener + Fixing, structural timber fasteners and UKCA (retrieved 15 October 2026)
  4. BS 1210:1963, withdrawn 1 July 2014 (retrieved 15 October 2026)
  5. bolts.co.uk, guide to common recess styles (retrieved 15 October 2026)
  6. B&Q, nails, screws and wall plugs (retrieved 15 October 2026)
  7. Screwsline, metric or imperial (retrieved 15 October 2026)
  8. TIMCO, stainless steel FAQ (retrieved 15 October 2026)