Directional boring is priced by the foot, and the honest answer to “what does it cost?” is a range: small-diameter conduit in cooperative soil commonly runs in the low double digits per foot, while large-diameter bores through rock can cost ten times that. The spread isn't padding — it's geology, diameter, and risk. Here's how the number is actually built.
Rule-of-thumb ranges
Industry rules of thumb as of 2026 — every real job prices from its own conditions:
| Small conduit (2–4"), soft soil | Roughly $8–$20 per foot |
|---|---|
| Mid-size (6–12"), mixed conditions | Roughly $20–$50 per foot |
| Urban work, congested utilities | Premiums for potholing, traffic control, tight tolerances |
| Rock boring | $100+ per foot is common; hard-rock crossings are engineered and priced individually |
| Mobilization | A fixed charge — commonly $1,500–$5,000+ — which is why short bores cost more per foot than long ones |
How the machine actually does the work is covered in our HDD explainer.
The six things that move the price
Ground conditions dominate. Sand and clay drill fast; cobble tears up tooling; solid rock means specialized heads, slower progress, and higher mud volumes. Diameter and depth set the reaming passes required — a bore twice the diameter is far more than twice the work. Length spreads mobilization but adds steering risk. Utility congestion means potholing every crossing utility before the drill passes — slow, mandatory, and worth every dollar against a gas-line strike. Drilling fluid logistics: mud must be mixed, managed, and legally disposed of. Restoration: what the surface must look like when the crew leaves.
One line item worth understanding: the locate-and-pothole work that precedes the drill is the cheapest insurance in underground construction.
Boring vs. open trench
Open trenching can be cheaper per foot in open ground — but boring wins whenever the surface matters: roads, driveways, landscaping, wetlands, rail, rivers. It also wins on restoration cost, traffic disruption, and increasingly on permit approval, which is why trenchless methods keep taking share. The right comparison is total installed cost including restoration and time, not the drill rate alone.
How to get a real number
Send a contractor the length, the product (conduit count and size), a site plan or even an aerial with the path marked, what's known about soils, and the required depth. A serious HDD contractor will come back with questions about utilities and access before a price — that's a good sign, not a delay. Nevantin prices bores across 12 states; the more of the above you send, the tighter the quote.