Cable Railing Post and Cable Spacing Guide
Calculate post counts, equal bay spacing, cable rows, and cable path length for a cleaner deck or stair railing plan.
Estimate posts and spacing for a straight run
Enter one straight termination-to-termination run. The calculator divides it into equal bays that do not exceed your selected maximum post spacing.
The three dimensions behind a cable railing layout
Post spacing, cable spacing, and railing height work together. Changing any one of them can affect deflection, row count, appearance, and the material list.
Keuka recommends no more than 48 inches between posts to help prevent flexible cable from separating under pressure.
Keuka recommends approximately 3-inch vertical cable spacing when planning around the 4-inch sphere rule.
The Keuka project estimator defaults to 11 rows for a 36-inch rail and 13 rows for a 42-inch rail.
Post counts at a 48-inch maximum
Each example assumes one isolated, straight run with a post at both ends. The calculator above handles other lengths and spacing limits.
| Run length | Equal bays | Total posts | Average spacing |
|---|---|---|---|
| 4 ft | 1 | 2 | 48 in |
| 8 ft | 2 | 3 | 48 in |
| 12 ft | 3 | 4 | 48 in |
| 16 ft | 4 | 5 | 48 in |
| 20 ft | 5 | 6 | 48 in |
Five spacing mistakes to catch before ordering
A clean run schedule makes these issues much easier to spot before posts are installed or cable is cut.
Using one perimeter total
Break the layout into straight runs so corners, openings, and hardware terminations stay visible.
Stretching post bays
Adding a few inches to every bay can create excessive cable movement across a long railing.
Counting stairs horizontally
Measure and plan stair runs along the diagonal cable path, not only across the floor.
Ignoring end-post loads
Termination posts and their attachments must be designed to resist the combined cable tension.
Assuming every corner shares
Single-post, double-post, and terminating corners can produce different post and hardware counts.
Cable railing spacing FAQ
These answers cover the practical spacing questions that usually come up while sketching a deck or stair layout.
How far apart should cable railing posts be?
Keuka Cable recommends a maximum distance of 48 inches between posts. Closer spacing can reduce cable deflection, while longer gaps may require a different engineered layout or intermediate support.
How far apart should horizontal railing cables be?
Keuka recommends approximately 3 inches of vertical spacing. Because cable is flexible, the installed system must still be planned so applicable opening limitations are maintained under expected conditions.
How many posts do I need for a 16-foot cable railing run?
At a 48-inch maximum spacing, one isolated 16-foot straight run divides into four equal bays and uses five posts, including the two end posts. Corners, stairs, gates, and shared posts can change the project total.
How many cable rows are used on a 36-inch or 42-inch railing?
The Keuka project estimator defaults to 11 cable rows for a 36-inch railing and 13 cable rows for a 42-inch railing. Confirm the final row count from the exact assembly and local requirements.
Can cable railing posts be more than 48 inches apart?
Keuka recommends keeping posts within 48 inches. Do not increase the spacing without confirming that the complete post, cable, attachment, and structural design meets the requirements for your project.
Turn the spacing plan into a complete material list.
Draw each level and stair run in the Keuka Cable Project Estimator to account for corners, post material, hardware configuration, cable finish, and optimized bundle lengths.