Steel Post Calculator
Work out how many steel posts you need for a retaining wall or fence run, based on length and spacing.
Steel Post Calculator
Work out how many steel posts you need for a wall or fence run, by spacing.
Calculating Steel Post Quantity
Steel H posts are the vertical structural members used in sleeper retaining walls, and this calculator extracts that single component so you can quickly estimate post quantity and cost for a run of any length. The formula is ceiling(run length ÷ post spacing) + 1 — a post at each end of the run, plus however many fit at your chosen spacing along the way.
Post cost is then calculated using standard supply rates for each post size — 100 UC, 125 UC or 150 UC — multiplied by your post quantity.
What Information You Need To Enter
Enter your total wall or fence run length in metres, select a post spacing between 1.2 m and 2.4 m, and choose a post type.
Understanding Your Results
You will see the number of steel posts required and an estimated post cost (ex GST). This is the post component only — for a full retaining wall estimate including sleepers, piers and drainage, use our Concrete Sleeper or Timber Sleeper Retaining Wall calculators.
Why Accurate Estimating Matters
Steel posts are a significant cost component of any sleeper retaining wall, so knowing the exact quantity and size needed helps you order the right materials and get an accurate sense of budget before finalising your wall design.
Frequently Asked Questions
What is a UC post?
UC stands for Universal Column, a standard structural steel section commonly used as posts in retaining walls due to its strength and profile, which suits slotting sleepers between the flanges.
What post spacing should I use?
Post spacing affects both cost and wall strength -- closer spacing uses more posts but can support taller walls or heavier loads. Your engineer or wall design will specify the required spacing for your project.
What size post do I need?
100 UC, 125 UC and 150 UC increase in size and strength respectively. Post size is generally determined by wall height and the loads being retained, confirmed by an engineer for taller or load-bearing walls.
Does this include installation cost?
No -- this calculator estimates post supply cost only. Installation, including any bored pier footings, is estimated separately in our Concrete Sleeper and Timber Sleeper Retaining Wall calculators.
Can steel posts be used for fencing as well as retaining walls?
Yes, the same spacing calculation applies to fence posts. This calculator is a general-purpose tool for any project using evenly spaced steel posts along a straight run.
Related Calculators & Services
Need An Exact Price, Not Just An Estimate?
The Steel Post Calculator gives you a fast, useful planning figure. For a fixed, accurate price backed by a site assessment, request a free professional quotation from HPL Construction.
