Nail Size Chart: Penny Sizing Explained (8d, 10d, 16d & More)
Grab a box of "16d" nails at the hardware store and you'll find at least three genuinely different products hiding behind that one label — common, sinker, and the shorter gun-nail version framers actually shoot most often. None of them are wrong, exactly, but they're not interchangeable either, and the "penny" system that names them doesn't map to any other measurement you already know. This guide covers the real dimensions behind every common penny size, the actual IRC code requirements for structural nailing, and the nail-type confusion that trips up even some building inspectors.
Quick answer: Nail "penny" size (the "d" you see on the box) indicates length only — it does NOT reliably indicate diameter. A 16d common nail is 3-1/2" long and 0.162" thick. A 16d sinker is 3-1/4" long and only 0.148" thick. A 16d "short" gun nail is 3-1/4" and just 0.131" thick. For code-required structural nailing, always specify length AND diameter AND type — not penny size alone.
| Penny Size | Length | Common Use |
|---|---|---|
| 8d | 2-1/2" | Sheathing, subfloor, furring strips |
| 10d | 3" | Toe-nailing, blocking, doubled studs |
| 16d | 3-1/2" | Wall framing, plates, rim joists |
See the complete chart with every type and diameter: jump down ↓
✓ Dimensions verified against IRC Table R602.3(1), APA, and Forest Products Laboratory data — not reseller estimates.
16d Types at a Glance
| Type | Length | Diameter | Structural? |
|---|---|---|---|
| Common | 3-1/2" | 0.162" | Yes — the IRC baseline |
| Sinker | 3-1/4" | 0.148" | Usually accepted, verify locally |
| Box | 3-1/2" | 0.135" | No — light-duty only |
| Gun Nail | 3-1/4" | 0.131" | Check connector rating first |
Quick Job Lookup
| Subfloor / wall sheathing | 6d common |
| Roof sheathing | 8d common |
| Toe-nailing / doubled studs | 10d common |
| Wall framing / plates / rim joists | 16d common |
| High wind zones (110+ mph) | 8d ring-shank (required) |
| Pressure-treated lumber | Hot-dip galvanized only |
Source: IRC Table R602.3(1) — see the full application chart below for spacing requirements.
What "Penny" Sizing Actually Means
The "d" after a nail size — 8d, 10d, 16d — stands for "penny," derived from the Roman denarius. The system dates to 15th-century England, where it originally indicated the price per hundred nails: a "10 penny" nail cost 10 pence per hundred. The pricing logic disappeared centuries ago, but the naming convention stuck, and it now indicates length only, with each penny size increasing by roughly 1/4" up to 12d, then jumping to larger increments beyond.
The critical thing the penny system does not reliably indicate: diameter. A 10d common nail, a 10d box nail, and a 10d sinker nail are all "10 penny" — and all three have different shank diameters (0.148", 0.128", and 0.120" respectively). The American Plywood Association's own technical guidance is explicit on this point: for anything structural, specify diameter and length together (e.g., "0.148" x 3" [10d common]"), not penny size alone.
Penny sizing history and APA guidance verified against APA technical documentation and standard fastener references — July 2026.
Full Nail Size Chart
| Penny Size | Length | Common Diameter | Gauge |
|---|---|---|---|
| 2d | 1" | 0.072" | 15 |
| 3d | 1-1/4" | 0.080" | 14 |
| 4d | 1-1/2" | 0.098" | 13 |
| 6d | 2" | 0.113" | 11-1/2 |
| 8d | 2-1/2" | 0.131" | 10-1/4 |
| 10d | 3" | 0.148" | 9 |
| 12d | 3-1/4" | 0.148" | 9 |
| 16d | 3-1/2" | 0.162" | 8 |
| 20d | 4" | 0.192" | 6 |
| 30d | 4-1/2" | 0.220" | 5 |
| 40d | 5" | 0.238" | 4 |
| 60d | 6" | 0.238" | 4 |
Diameters shown are for common nails specifically — sinker, box, and gun nails of the same penny size run thinner. See the next section for exact differences. Sizes beyond 60d are technically "spikes," not nails, and are specified by length and diameter directly rather than penny size.
Common vs. Sinker vs. Box: The Same "16d" Isn't the Same Nail
This is the single biggest source of confusion in nail sizing, and it genuinely trips up professionals, not just DIYers — a real building-code forum thread shows inspectors disagreeing on whether a sinker satisfies a code callout for "common" nails.
Length and diameter figures per JLC, American Fasteners Co., and manufacturer spec sheets — verified July 2026. Diameter cross-sections shown at 40× magnification since the true differences are too small to see at actual scale.
| Type | Length | Diameter | Head | Notes |
|---|---|---|---|---|
| 16d Common | 3-1/2" | 0.162" | Full, round, smooth | The baseline the IRC calls out by default |
| 16d Sinker | 3-1/4" | 0.148" | Checkered, flush-driving | Vinyl/resin coated for easier driving; thinner and shorter than common |
| 16d Box | 3-1/2" | 0.135" | Full, round, smooth | Thinner shank reduces splitting but also reduces shear strength — not for structural framing |
| 16d Gun Nail | 3-1/4" | 0.131" | Clipped or offset round | What most collated framing nailers actually shoot — thinner than true 16d common |
Why this matters beyond terminology: Simpson Strong-Tie's own connector hardware specifies load values based on true common-nail diameter. Substituting a 0.131" gun nail where a connector is rated for 0.162" common nails can mean a real reduction in rated capacity — some sources cite roughly a 16-20% load reduction using sinkers or shorts in place of true commons on hardware connections. Always check the specific hardware manufacturer's fastener schedule rather than assuming any "16d" nail satisfies the spec.
Dimensional data cross-verified against JLC (Journal of Light Construction), American Fasteners Co., and manufacturer spec sheets — July 2026.
Which Nail for Which Job (IRC-Referenced)
These are the real requirements from IRC Table R602.3(1), the code table that governs structural nailing in most U.S. residential construction. Always verify against your local jurisdiction's adopted code edition and any engineer's specifications, which take precedence over these general defaults.
| Application | Nail | Spacing |
|---|---|---|
| Subfloor / wall sheathing (3/8"-1/2") | 6d common (2"×0.113") | 6" edges / 12" field |
| Roof sheathing (19/32"-1") | 8d common (2-1/2"×0.131") | 6" edges / 12" field |
| Thicker wall sheathing (1-1/8"-1-1/4") | 10d common or 8d deformed | 6" edges / 12" field |
| Wall framing / top & bottom plates | 16d common | 16" o.c. typical |
| Toe-nailing studs to plate | 10d common (or 3× 8d) | Per connection |
| Doubled studs / built-up posts | 10d common | 24" o.c. staggered |
| High wind zones (110+ mph) | 8d ring-shank (deformed) required | 6" edges, code-specified |
One detail worth knowing that many general contractors miss: pressure-treated lumber requires hot-dip galvanized nails specifically — not just "coated" or vinyl-sinker nails. Borate-treated lumber is the one exception where clear zinc coating is acceptable. Using the wrong coating on PT lumber leads to accelerated corrosion from the copper-based preservatives in modern treated wood.
Fastener schedule verified against IRC Table R602.3(1) (ICC official documentation) — July 2026. Always confirm your local jurisdiction's adopted code edition.
Nail Gauge Explained
Gauge measures shank thickness directly, and it runs opposite to how you'd expect: a lower gauge number means a thicker nail. A 6-gauge nail is thick and heavy-duty; a 16-gauge nail (like most brad nailer fasteners) is thin and light-duty. This is the same inverse-numbering convention used in wire and sheet metal gauge, and it trips up the same people every time.
Gauge and penny size measure two different things — length (penny) and thickness (gauge) — and neither one implies the other reliably, for the same reason common/sinker/box nails of the same penny size have different diameters. When precision matters, specify both, or specify diameter directly in decimal inches or millimeters.
Ring Shank vs. Smooth Shank
Beyond length and diameter, shank profile is a real, separate variable that affects holding power directly. The U.S. Forest Products Laboratory has measured ring-shank (also called annular or deformed) nails at roughly double the withdrawal strength of smooth-shank nails of the same size — the rings bite into wood fiber and resist being pulled straight back out, where a smooth shank relies on friction alone.
The ICC's own code classification reflects this directly: smooth-shank nails are officially termed "common," while ring-shank and screw-shank nails are termed "deformed." Deformed nails aren't just a nice-to-have upgrade — they're required by code in specific conditions: high-wind zones (110+ mph design wind speed) and certain subfloor assemblies where sustained vibration or seasonal wood movement would otherwise work smooth nails loose over time.
The tradeoff worth knowing: ring-shank nails resist withdrawal better, but several experienced framers report they can be harder to remove cleanly if you make a mistake, and the added friction during driving can be tougher on a nail gun or on your arm with a hammer. For anything permanent and load-bearing, that tradeoff favors ring-shank. For temporary work you expect to disassemble — form work, temporary bracing — smooth shank or duplex (double-head) nails remain the better choice specifically because they come back out cleanly.
Withdrawal strength data per U.S. Forest Products Laboratory research; code classification per ICC/IRC — July 2026.
Canada & Metric Nail Sizing
Here's something most nail-sizing guides skip entirely: Canada does not use the U.S. penny system for nails. Per the Canadian Wood Council, Canadian nails are specified by length (typically still in inches for construction lumber, since dimensional lumber sizing remains imperial on both sides of the border) and by gauge number for diameter — not by "d" designation. If you're working from a Canadian spec sheet or supplier catalog and see a nail called out as "3-1/2", 10 gauge" rather than "16d," that's the same convention difference, not a different product.
Most of the rest of the world uses pure metric nail sizing — described simply as length × diameter in millimeters (e.g., "90 × 3.8mm"), with no penny or gauge system involved at all. If you're sourcing hardware internationally or working from imported plans, converting to the nearest millimeter equivalent is more reliable than trying to force a penny-size match.
Canadian nail sizing convention verified against Canadian Wood Council (CWC) technical documentation — July 2026.
Recommended Nails by Type
Grip-Rite is the dominant professional brand for loose construction nails in North America, manufactured by PrimeSource Building Products. The products below match the specific types discussed above.
Prices and availability change — links go to current Amazon listings. As an Amazon Associate, BuildToolHQ earns from qualifying purchases.
Common Mistakes
Frequently Asked Questions
What does the "d" in nail sizes like 16d mean?
"D" stands for "penny," from the Roman denarius. It's a legacy English system dating to the 1400s that originally indicated the price per hundred nails. Today it indicates length only — not diameter, gauge, or any other measurement.
Is a 16d sinker the same as a 16d common nail?
No. A 16d common nail is 3-1/2" long and 0.162" in diameter. A 16d sinker is slightly shorter (about 3-1/4") and noticeably thinner (0.148"), with a checkered head designed to drive flush. They're both legitimately called "16d," but they're different products with different structural capacities.
What size nail do I need for framing?
16d common nails are the standard for wall framing, top/bottom plates, and rim joists. 10d is typical for toe-nailing and doubled studs. 8d covers sheathing and subfloor. Always verify against your specific engineer's plans or local code, which take precedence over these general defaults.
Can I use sinker nails instead of common nails for structural framing?
Not automatically. Sinkers have a thinner shank than true common nails, which reduces shear strength. Some hardware manufacturers' load tables account for this with a real capacity reduction (some sources cite roughly 16-20%). Check the specific fastener schedule for your application rather than assuming equivalence.
What's the difference between nail gauge and penny size?
Penny size (the "d" number) indicates length. Gauge indicates shank thickness, and runs in reverse — a lower gauge number means a thicker nail. The two measurements are independent; a nail's penny size doesn't tell you its gauge, and vice versa.
Do I need ring shank nails, or are smooth shank nails fine?
For anything permanent and load-bearing, ring shank ("deformed") nails hold roughly twice as well against withdrawal, per Forest Products Laboratory testing, and are required by code in high-wind zones and certain subfloor assemblies. Smooth shank is acceptable for many general framing applications and preferred for temporary work you'll disassemble later.
Does Canada use the same nail sizing system as the US?
No. Canada does not use the penny (d) system. Canadian nails are specified by length and gauge number rather than penny designation, per the Canadian Wood Council. If you're working from a Canadian spec sheet, expect to see dimensions and gauge rather than "16d"-style callouts.
Related Guides
- Joist Hanger Screws vs Nails — What the code actually requires for structural fastening
- Deck Screws Complete Guide — The screw-side equivalent of this chart
- Screw Pilot Hole Size Chart — Matching pilot holes to screw sizes
- Wood Screw Size Chart — Full wood screw sizing reference
Free Tool · AI-Powered
Plan your whole project in 2 minutes
Tell our AI Foreman what you are building and get a complete tool list, materials shopping list, step-by-step plan, and mistakes to avoid.
Try the AI Foreman →
Thomas Leroy
Contractor and founder of BuildToolHQ. 15+ years working with concrete, masonry, and structural fastening on residential and commercial job sites across North America. I built this site to give tradespeople and serious DIYers the same technical knowledge professionals use every day.
More about Thomas
