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Stud Boring and Notching Limit Calculator

Work out how large a hole may be bored through a stud and how deep a notch may be cut, before the framing has to be doubled or a protection plate added.

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The dressed depth of the stud — the dimension the drill passes across.

The code calls this the stud's width, which reads oddly on site: it is the deeper of the two dressed dimensions, 3½ in on a 2x4, and every percentage below is taken from it. The 1½ in thickness the bit actually travels through is not what limits the hole.

Whether the wall carries load from above, or only its own weight and finishes.

The two cases are governed separately and the gap is wide: a non-bearing partition may be notched to 40% of the stud and bored to 60%, while a bearing wall is held to 25% and 40%. If you are unsure whether a wall is bearing, treat it as bearing.

Whether the stud being drilled has been doubled up to carry a larger hole.

Doubling is what buys the larger bore in a bearing wall — up to 60% of the stud width rather than 40%. The allowance runs out quickly: the code permits no more than two successive doubled studs to be bored, so a run of large penetrations needs a header, not more doubling.

Whether the service passes through a drilled hole or sits in an edge notch.

A bore leaves material on both sides of the service and is always the better cut where there is a choice. A notch removes the outer fibre where the bending stress is highest, which is why its allowance is smaller, and it puts the pipe or cable at the face where a nail can reach it.

The size you intend to cut — the hole's diameter, or the depth of the notch.

Use the finished cut, not the pipe: a copper tube needs a hole a size over its outside diameter to pass without binding, and an insulated waste pipe needs clearance around the lagging as well. The cover figure below assumes a bored hole is centred across the stud; a hole drilled off centre loses cover on one side twice as fast.

Maximum permitted bore or notch

1.4 in

High confidence

The planned cut is within the 1.40 in the code allows for this stud. Enough wood remains between the service and the face that no protection plate is required, though many inspectors expect one anyway where a fastener could plausibly find the pipe. A bored hole and a notch may not share the same section of stud.

Largest bore this stud allows
1.4 in
Deepest notch this stud allows
0.88 in
Cover left to the nearest face
1.32 in
Minimum clearance to the stud edge
0.63 in
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • International Residential Code R602.6, drilling and notching of studs: notches limited to 25% of the stud width in an exterior wall or bearing partition and 40% in a non-bearing partition; bored holes limited to 40% of the stud width, or 60% where the stud is doubled in a bearing wall, with the hole edge no nearer than 5/8 in (16 mm) to the edge of the stud
  • NFPA 70 (National Electrical Code) 300.4(A)(1): where the edge of a bored hole is less than 1-1/4 in (32 mm) from the nearest edge of the wood member, a steel plate not less than 1/16 in (1.6 mm) thick is required; notched members are protected the same way
  • Adoption varies. Local amendments to the IRC change these percentages in some jurisdictions, and engineered or finger-jointed studs are governed by the manufacturer's evaluation report instead

Inputs used

Stud Size
2x4 — 3½ in / 89 mm dressed
Wall Type
Exterior wall or bearing partition
Stud Condition
Single stud
Cut Being Made
Bored hole through the stud
Planned Hole Diameter or Notch Depth
0.87 in

Intermediate steps

Largest bore this stud allows
1.4 in
Deepest notch this stud allows
0.88 in
Cover left to the nearest face
1.32 in
Minimum clearance to the stud edge
0.63 in
Final result1.4 in

Confidence note: The planned cut is within the 1.40 in the code allows for this stud. Enough wood remains between the service and the face that no protection plate is required, though many inspectors expect one anyway where a fastener could plausibly find the pipe. A bored hole and a notch may not share the same section of stud.

What this calculation does not cover

  • Sawn lumber studs only. Engineered, finger-jointed and cold-formed steel studs are governed by their own evaluation reports, which usually permit larger holes in defined positions and no notching at all.
  • Does not check shear walls or braced wall panels, where sheathing nailing and hold-downs impose their own restrictions on what may be cut.

Add the equipment this sizes

This result is a specification — 1.4 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-30 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations3
  1. International Residential Code R602.6, drilling and notching of studs: notches limited to 25% of the stud width in an exterior wall or bearing partition and 40% in a non-bearing partition; bored holes limited to 40% of the stud width, or 60% where the stud is doubled in a bearing wall, with the hole edge no nearer than 5/8 in (16 mm) to the edge of the stud
  2. NFPA 70 (National Electrical Code) 300.4(A)(1): where the edge of a bored hole is less than 1-1/4 in (32 mm) from the nearest edge of the wood member, a steel plate not less than 1/16 in (1.6 mm) thick is required; notched members are protected the same way
  3. Adoption varies. Local amendments to the IRC change these percentages in some jurisdictions, and engineered or finger-jointed studs are governed by the manufacturer's evaluation report instead

Which documents these citations point at

  • International Residential Code — R602.6 (United States)One- and two-family dwellings and townhouses up to three storeys — structure, fire safety, energy, plumbing, mechanical and electrical in a single document.
  • National Electrical Code (NFPA 70) (United States)Electrical installations — conductor sizing and protection, load calculation, wiring methods, grounding and working clearances.

A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.

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Tools and safety for this job

To frame a stud wall and cut framing lumber. Generic types, no brands, no prices.

Protection this work requires

  • Hardwood dust is a recognised carcinogen: extract at the tool and wear a P2/N95 respirator when cutting or sanding indoors.
  • Saws, grinders and breakers run above 85 dB, where hearing damage accumulates and does not recover: defenders or plugs for every cut, not just the long ones.
  • Nailing, chiselling and cutting all throw fragments: glasses to EN 166 or ANSI Z87.1, and goggles rather than glasses overhead.
Show the 9 tools this job needs

Essential

  • Circular saw

  • Claw hammer

  • Combination or framing square

  • Spirit level

  • Tape measure

Recommended

  • Chalk line

  • Framing nailer

  • Mitre saw

Optional

  • Hand saw

Also needed as materials: chalk refill, circular saw blades, framing nails, fuel cells, mitre saw blades.

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Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Called something else where you work? Noggins and blocking · Chase and safe zone — the term in each market, how close the equivalence really is, and the standard that governs it.

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How to calculate stud boring and notching limit in 6 steps

  1. Stud SizeThe dressed depth of the stud — the dimension the drill passes across.
  2. Wall TypeWhether the wall carries load from above, or only its own weight and finishes.
  3. Stud ConditionWhether the stud being drilled has been doubled up to carry a larger hole.
  4. Cut Being MadeWhether the service passes through a drilled hole or sits in an edge notch.
  5. Planned Hole Diameter or Notch DepthThe size you intend to cut — the hole's diameter, or the depth of the notch.
  6. Maximum permitted bore or notchThe tool computes the maximum permitted bore or notch from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

Why may a non-bearing partition be cut so much harder than a bearing wall?
Because the stud in a partition is carrying almost nothing. Its job is to hold the finishes flat and resist the small lateral load of someone leaning on the wall, so removing 40% of it in a notch leaves ample capacity. A stud in a bearing wall is carrying roof or floor load in compression, and a deep notch both reduces the area taking that load and creates the eccentricity that starts a buckle.
Can I put a hole and a notch in the same stud?
Not at the same height. The code is explicit that a bored hole may not be located at the same section of stud as a cut or notch, because the two remove material from the same cross-section and the remaining timber is far less than either allowance implies. Separate them vertically by enough that no single horizontal slice through the stud contains both.
When exactly does a steel protection plate become mandatory?
When less than 1-1/4 in of wood is left between the edge of the hole or notch and the face of the framing member, measured on the side the drywall screws or siding nails will come from. The plate must be at least 1/16 in thick steel and must cover the vulnerable zone. A notch always triggers this, because the service sits at the face with no cover at all.
Does doubling a stud let me keep boring big holes all the way along the wall?
No. The 60% allowance in a bearing wall applies to a doubled stud, and no more than two successive doubled studs may be bored. A run of large penetrations — a soil stack turning, or a duct crossing — has passed the point where boring is the right answer, and needs a proper header with trimmers carrying the load around the opening.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.