Calculate how many joist hangers you need for a deck or floor from the width and joist spacing, plus nail counts for common LUS hangers.
Joist Hanger Formula
The count starts with the joists. Divide the deck or floor width by the on-center joist spacing, round up, and add one for the joist that closes the far side:
Joists = CEILING(W / S) + 1
Multiply the joist count by the number of hangers each joist needs and by the number of identical framing runs to get the hangers you install:
Hangers = Joists * E * R
Each hanger is nailed off through a fixed set of holes, so the fasteners you order scale with the hanger count. Multiply the number of hangers by the nails each one takes:
Nails = Hangers * (Fh + Fj)
Variables:
- W is the layout width across the joists, perpendicular to their length; it is not the joist span between bearing supports
- S is the on-center joist spacing in the same unit as W
- E is the number of hangers per joist: 1 for a ledger-and-beam layout where the far end bears on a beam, or 2 when both ends sit in hangers
- R is the number of identical framing runs, or sections
- Fh is the number of nails driven into the header or ledger, and Fj is the number driven into the joist face
The spacing input drives the joist count, with a joist assumed at each edge and a shorter final spacing where needed. The support option sets E to one or two hangers per counted joist. Repeated runs and extra hardware can add two border joists and other extra joists per run, extra hangers across all runs, and spare hangers. Installed hangers = (base joists + border joists + extra joists) × E × R + extra hangers. Purchase quantity = CEILING(installed hangers × (1 + spare percentage / 100)). The fastener schedule is selected separately; mixed hanger models need separate calculations.
Hanger Model and Nail Count by Joist Size
These example nail counts apply to the exact listed single LUS hanger models with the specified nail schedule. Nominal joist size alone does not select a safe hanger, its fasteners or its load rating. Select Hangers only to omit fasteners, a listed nail schedule, or Enter manufacturer fastener counts for an exact custom schedule.
| Joist size | Typical hanger | Header nails | Joist nails | Nails per hanger |
|---|---|---|---|---|
| 2×6 | LUS26 | 4 | 4 | 8 |
| 2×8 | LUS28 | 6 | 4 | 10 |
| 2×10 | LUS210 | 8 | 4 | 12 |
| Other sizes or models | Exact manufacturer model required | Enter schedule | Enter schedule | Header + joist counts |
The joist nails on a double-shear hanger are driven at an angle through the joist and into the header, which is what lets the design reach its load with fewer joist nails. Counts are for single hangers with standard 0.148 in. by 3 in. connector nails. Confirm the model and its nail schedule against the manufacturer table before ordering.
This second table shows the joists and hangers for common deck widths at 16 in. on-center spacing, so you can sanity check the calculator at a glance.
| Deck width | Joists | Hangers (1 per joist) | Hangers (2 per joist) |
|---|---|---|---|
| 8 ft | 7 | 7 | 14 |
| 10 ft | 9 | 9 | 18 |
| 12 ft | 10 | 10 | 20 |
| 14 ft | 12 | 12 | 24 |
| 16 ft | 13 | 13 | 26 |
| 20 ft | 16 | 16 | 32 |
Example Problems
Example 1: Count hangers and nails for a ledger-and-beam deck.
Your deck is 12 ft wide across the joists, framed at 16 in. on-center with 2×8 joists. The house side uses a ledger with hangers and the outer end bears on a beam, so each joist takes one hanger. Joists = CEILING(12 / (16 / 12)) + 1 = 9 + 1 = 10. Hangers = 10 * 1 * 1 = 10. Each LUS28 takes 10 nails, so Nails = 10 * 10 = 100, which is 60 into the ledger and 40 into the joists.
Example 2: Both ends hung.
A 16 ft floor is framed at 12 in. on-center with 2×10 joists, hung in connectors at both ends. Joists = CEILING(16 / 1) + 1 = 16 + 1 = 17. Hangers = 17 * 2 = 34. Each LUS210 takes 12 nails, so Nails = 34 * 12 = 408, split as 272 header nails and 136 joist nails. Add a 5 to 10 percent spare on the hangers if you want a buffer for damage.
Frequently Asked Questions
How many joist hangers do I need?
Count the joists, then multiply by the hangers each joist needs. The joist count is the deck width divided by the on-center spacing, rounded up, plus one. A layout with a ledger on one side and a beam on the other usually takes one hanger per joist. A layout hung in connectors at both ends takes two. Rim joists, beams, and posts use their own hardware and are counted separately.
How many nails go in one joist hanger?
Follow the exact manufacturer installation schedule and listed load table. The example single LUS26, LUS28 and LUS210 nail schedules use 8, 10 and 12 nails respectively; other models or fastener substitutions can differ. Double-shear joist fasteners are angled through the joist into the header. The calculator counts quantities only and does not verify capacity or code compliance.
Can I use screws instead of joist hanger nails?
Use only an exact connector-screw substitution listed by the hanger manufacturer for that model and installation; its screw counts and load adjustments may differ from the nail schedule. Standard deck or drywall screws are not substitutes. For double-shear joist fasteners, follow the listed penetration length: short 1.5 in. nails must not be substituted for the specified long joist nails. Enter the approved screw counts using the custom schedule.
