How to Bid an HVAC Job: A Step-by-Step Guide
To bid an HVAC job, read the mechanical plans and schedules, take off ductwork by linear foot and equipment by count, apply labor units in hours per unit, price material, then add overhead and profit. Combined markup commonly runs 25 to 45 percent on the total job cost.
The equipment cost on an HVAC bid is the easy part. The money is won or lost in the ductwork details and the labor hours, and both hide inside the mechanical plans. This guide covers how to bid an HVAC job from reading the drawings through final markup, so your number reflects the real installed cost rather than a hopeful guess.
Step 1: Read the Mechanical Plans and Schedules
Begin with three documents: the mechanical legend, the equipment schedule, and the floor plans. The legend decodes every symbol. The equipment schedule lists each unit by tag, for example RTU-1 or AHU-2, with tonnage, CFM, electrical, and specs. The plans show duct routing, diffuser and grille locations, and where you tie into existing systems.
Cross-reference tags across every sheet. A single rooftop unit may appear on the schedule, the roof plan, and an electrical sheet, and missing one or counting it twice can swing a bid by thousands of dollars. Note ceiling heights and accessibility too, because a 30-foot ceiling changes your labor far more than the duct length alone suggests.
Step 2: Take Off the Ductwork
Ductwork is the largest variable in most HVAC bids. Measure and tally it in clear categories:
- Straight duct: linear feet by size and gauge, supply and return separately
- Fittings: elbows, transitions, takeoffs, and offsets counted individually
- Terminal devices: supply diffusers, return grilles, and registers, counted by type
- Accessories: dampers, flex connectors, access doors, and insulation
Many estimators also convert sheet metal to pounds, since material cost and shop labor track with gauge and weight. A 1,000-square-foot duct system can run several thousand pounds of metal, and fittings, though small in length, often carry the heaviest labor per piece.
Step 3: Take Off the Equipment
Now count the big-ticket items straight from the schedule. List each rooftop unit, air handler, condenser, furnace, VAV box, exhaust fan, and similar, with its tag and specs. Pull live pricing or current quotes rather than stale numbers, since equipment costs move and a six-month-old price can erase your margin on a single unit.
Add the items that ride with each piece of equipment: curbs, hanging steel, refrigerant line sets, condensate drains, controls, and electrical disconnects where they fall in your scope. These attachments are routinely forgotten and quietly add 10 to 20 percent to equipment-related cost.
Step 4: Apply Labor Units
Convert quantities to hours using labor units, the standard install time per item. Example benchmarks:
| Item | Typical labor unit |
|---|---|
| Rectangular duct | ~0.10–0.20 hr per lb |
| Round duct | ~0.05–0.10 hr per lb |
| Fittings | counted, higher hours each |
| Rooftop unit (small) | 8–24 hr per unit |
| Diffuser / grille | 0.5–1.0 hr each |
Multiply each labor unit by your takeoff quantity to get hours, then multiply hours by your fully burdened labor rate. At $65 per hour, 400 labor hours is $26,000 of installed labor before you have priced a single component. Adjust units up for tight access, high ceilings, or occupied retrofits.
Step 5: Price Material and Add Indirect Costs
Total your material: duct and fittings, equipment, terminal devices, refrigerant, controls, hangers, fasteners, and insulation. Then add the indirect costs that real jobs carry but plans never show:
- Equipment rental: lifts, cranes for rooftop sets
- Permits, inspections, and engineering if in scope
- Startup, testing, and air balancing
- Freight and small consumables
If you would rather pull duct linear feet, fitting counts, and equipment tags off the plans automatically, HVAC estimating software can draft the takeoff and labor units for you to review before pricing.
Step 6: Apply Overhead and Profit
Add your labor, material, and indirect costs to get total job cost, then apply overhead and profit. Overhead covers your shop, trucks, and office; profit is your retained margin. HVAC contractors commonly add a combined 25 to 45 percent, with service and small jobs at the higher end and large competitive bids at the lower end.
On a $100,000 cost base, a 30 percent markup yields a $130,000 bid. Be deliberate about markup versus margin: a 30 percent markup on cost is roughly a 23 percent margin on price, so quote the figure you actually mean.
New Construction vs Retrofit
The same six steps apply, but a retrofit changes your labor far more than your material. On new construction, ductwork installs in open ceilings with clear access, and your labor units hold close to the benchmarks. On a retrofit, you fight existing structure, occupied spaces, after-hours schedules, and demolition of the old system. It is common to inflate retrofit labor units by 20 to 40 percent to reflect that friction.
Tie-ins are the classic retrofit trap. Connecting new duct to an existing trunk, matching old equipment controls, or working around live systems can each add hours that never appear on the plans. Walk the site before bidding a retrofit whenever you can, because the drawings show the design intent, not the access reality your crew will face.
Build Your Bid Around Risk
A defensible HVAC bid separates known costs from uncertain ones. Your duct and equipment quantities are knowable from the plans; your exposure to access problems, schedule changes, and tie-in surprises is not. Strong estimators price the knowns tightly and carry a visible contingency, often 3 to 10 percent, for the unknowns instead of padding every line. That keeps you competitive on the parts a GC can compare while still protecting you from the parts they cannot see.
Common HVAC Bidding Mistakes
- Undercounting labor. Fittings, hangers, access, and startup hours are the usual gaps.
- Missing equipment attachments. Curbs, disconnects, and line sets add up fast.
- Stale equipment pricing. Re-quote big units close to bid day.
- Ignoring jobsite conditions. Height, occupancy, and access reshape labor.
- Forgetting test and balance. Commissioning is real scope, not a freebie.
- Confusing markup with margin. Know which one your bid reflects.
Work this sequence on every job and your HVAC bids will hold up under scrutiny and still leave profit. Whatever tool you use, treat any automated takeoff as a draft to verify against the plans and the field before you submit.