A 20-foot 4×4 treated post typically costs $35-$85 before tax, with many standard pressure-treated posts near $55. Price depends on treatment rating, wood species, local stock, delivery distance, and whether the post is installed or bought as lumber only.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Post only | $35 | $55 | $85 | One 20-foot pressure-treated 4×4 |
| Post with sales tax | $37 | $59 | $93 | Tax varies by location |
| Delivered post | $55 | $90 | $160 | May include a delivery minimum |
| Installed post | $110 | $190 | $350 | Assumes ordinary access and basic setting |
Assumptions: U.S. retail pricing for a standard pressure-treated post; custom species, special treatment, and difficult delivery can cost more.
What a 20-foot treated 4×4 usually costs
For the post alone, a useful budget is $35-$85 each, or roughly $1.75-$4.25 per linear foot. The average is about $55, equivalent to $2.75 per linear foot. These prices generally refer to nominal 4×4 lumber, which measures about 3.5 by 3.5 inches after milling, not a full 4-inch square.
Lower-priced posts are more likely to be common pressure-treated Southern yellow pine at a large retailer or lumberyard. Higher prices may reflect limited local inventory, higher-grade stock, a particular treatment rating, or a special order. A 20-foot length is less commonly stocked than shorter posts, so the listed price may not include sourcing or freight.
Prices are not uniform nationwide. Store promotions, lumber supply, and local handling charges can shift a quote. Confirm whether the price is for one full-length post, whether the piece is straight and usable, and whether pickup or delivery is included.
How lumber, delivery, and labor shape the quote
A purchase quote can include more than the wood. Delivery and handling may add as much as the post itself when only one long piece is ordered. The table gives planning ranges for a single-post purchase or basic installation, not guaranteed contractor rates.
| Quote item | Typical range | Pricing basis | What changes it |
|---|---|---|---|
| Treated post | $35-$85 | $1.75-$4.25 per linear ft | Species, grade, treatment, stock |
| Delivery | $20-$75 | Per order, sometimes more | Distance, truck minimum, length |
| Cutting or handling | $0-$25 | Per post or cut | Retailer service and custom cuts |
| Basic installation labor | $50-$150 | About $50-$100 per hour | Digging, access, crew minimum |
| Concrete and small supplies | $10-$35 | Per post | Hole size and setting method |
Labor estimates vary with the project: setting a post in an open, prepared hole is different from removing an old post or digging through roots. A contractor may also charge a minimum visit fee, so labor per post falls when several posts are installed together.
Which treatment rating and dimensions change the price?
Check the label for the intended use rather than assuming every treated 4×4 is suitable for burial. Ground-contact treatment is the relevant specification when the post will sit in soil or contact concrete near grade. Above-ground-rated lumber may cost less, but it is not an equivalent substitute for a buried post.
Length and straightness matter, too. A 20-foot board can have more bow or twist than a shorter piece, and selecting a straight post may limit the usable stock. A custom order for a specific grade, species, or treatment can raise the material quote by roughly 10%-30% compared with readily available stock, depending on the supplier.
Confirm whether the lumber is pressure-treated for the application, and follow the product label for cutting, handling, and end-treatment instructions. If the post will support a deck, roof, gate, or other structural load, its size and spacing should be checked against the project design and local code; price alone does not establish suitability.
Does delivery or installation cost more for a 20-foot post?
Often, yes. A 20-foot post needs a vehicle capable of carrying long material safely, and some retailers limit how far lumber can extend beyond a truck bed. One-post delivery commonly costs $20-$75 before any special long-load charge. Ask for the total delivered price and confirm unloading arrangements before ordering.
Basic installation can add about $50-$150 in labor, excluding unusual excavation or removal. A contractor might quote more if the site has rocky soil, buried utilities, steep access, or a post that must be plumbed and braced while concrete cures. For a fence or run of supports, request pricing for the full quantity rather than multiplying a single-post minimum.
When a cheaper or stronger post is worth comparing
A standard treated 4×4 is usually the lowest-cost option for a light-duty application where the design allows it. Compare the total installed price, not just the lumber price, before switching sizes or materials. A shorter post cut from a 20-foot length may leave useful offcuts, but it does not make sense if the project requires the full length.
A 6×6 treated post costs more, often roughly $70-$150 for a 20-foot length when available, but may be specified for heavier loads or reduced movement. Cedar or naturally durable alternatives can also cost more and may not provide the same treatment rating. Do not substitute a smaller or untreated post where the plans call for ground-contact treated lumber.
How to lower the price without buying the wrong post
Get quotes from a lumberyard and at least one major retailer, asking each for the same 20-foot length, nominal size, treatment category, and grade. Comparing matching specifications prevents a low quote from hiding a less suitable product. Ask whether the item is in stock, special-order, or subject to a freight fee.
Delivery is often the most controllable extra. If safe transport is available, compare store pickup with delivery; otherwise, combine the post with other lumber purchases to spread a delivery minimum across the order. Inspect the post before accepting it, since replacing a bowed or damaged long piece after delivery may mean another trip or fee.
For installation, prepare the work area and confirm utility locations before the crew arrives. Grouping multiple posts into one job can reduce per-post labor, while avoiding unnecessary upgrades keeps material costs in check. Get a written quote that separates lumber, delivery, excavation, concrete, disposal, and tax.