Picture this hypothetical: you're bidding a mid-size commercial office building and three HVAC subs send numbers. The spread is wide, and when you read the proposals line by line, most of the gap isn't price. It's scope: one sub left out controls, another left out startup and the curbs, and a third included the crane while the others assumed you'd cover it.
That's the problem with searching for free HVAC bidding software. The phrase covers three different jobs, and free tools rarely handle all of them. This article gives you a map of what free actually buys, a plan-page fit test with worked arithmetic, and an HVAC bid-leveling checklist you can use today.
Short answer: for $0, STACK's free account covers takeoff on one small project a month, and PlanHub GC Essentials covers project posting, bid management and basic leveling. Neither prices the job for you or catches scope gaps between HVAC sub bids, so the leveling checklist below matters more than the tool. If you price HVAC yourself on most jobs, start with our HVAC estimating software guide and the HVAC takeoffs walkthrough.
Quick Picks
- Free takeoff on one small job a month: STACK's free account (300 pages, 50 measurements per project).
- Free sub invitations and basic leveling: PlanHub GC Essentials.
- Low volume and a disciplined estimator: a spreadsheet plus an email thread.
- Takeoff through a priced estimate, no seat license: Struvia, which is free to try on a few real plan sets and then bills on usage.
- Automated takeoff for a team that prices elsewhere: Togal Growth at $299 per user/month, billed yearly.
Three Jobs Hiding Inside "Free HVAC Bidding Software"
When a GC types that phrase, they usually mean one of three tasks. Name yours before you compare tools, because a free option for one task often does nothing for the others.
Pricing HVAC scope yourself
This is takeoff and estimating of equipment, ductwork, piping and accessories. You need it when you self-perform, when you're bidding remodel work with a small mechanical scope, or when you want a budget number before subs respond. It's the job most people mean by HVAC estimating software, and it's the one where free plans tend to hit page and measurement caps first.
Inviting and tracking HVAC sub bids
This is bid invitations, plan distribution, follow-up and addenda tracking. The work is mostly communication and record-keeping. If your invitations are inconsistent, start with our invitation to bid template and the construction RFQ template rather than rebuilding them from scratch.
Leveling HVAC bids so they compare
This is where HVAC bids go wrong. Scope gaps hide inside low numbers, and a proposal that looks cheapest may simply be shorter. Our bid leveling guide covers the general method. The HVAC-specific version, with a checklist and worked example, comes later in this article.
What Free HVAC Bidding Software Covers: STACK, PlanHub, Spreadsheets
What follows comes from each vendor's own pricing page, checked in November 2026. Plans change, so recheck before you rely on any of them.
STACK's free account: the limits that matter for HVAC
According to STACK's official pricing page, the free account, after a 7-day Pro trial, lists one active project per month, up to 300 pages, and 50 measurements per project. Paid plans start at Premium, $299 per user/month billed annually, for unlimited projects and AI takeoff. Pro, at $349 per user/month, adds worksheet estimating and native proposals.
For HVAC, the 300-page and 50-measurement limits are the numbers to test against your plan sets, which the next section does.
PlanHub GC Essentials: bid management without a base cost
PlanHub's official GC page lists GC Essentials with no base cost for project posting, bid management and basic leveling. That addresses the second and third jobs, at least at a basic level.
PlanHub doesn't publish prices for its paid GC tiers (Pro, Premier and Enterprise); a product specialist quotes them. Subcontractor lead subscriptions are a separate purchase from the GC side.
The spreadsheet-and-email route
For low volume, a spreadsheet and an email thread cost nothing in software and a lot in attention. You send invitations, track responses in a sheet, and level bids by hand. It works if you're disciplined about scope line items.
Our guides to a bid leveling spreadsheet and free construction estimating software cover this route in full, so I won't repeat them here.
Comparison table: free, free-ish and paid starting points
| Tool | Best For | Key Strength | Key Limitation | Est. Cost |
|---|---|---|---|---|
| STACK free account | Testing takeoff on one small project | Free entry after the Pro trial | One active project/month, up to 300 pages, 50 measurements/project | $0; Premium $299 / Pro $349 per user/month, billed annually |
| PlanHub GC Essentials | Posting projects and basic bid management | No base cost for posting, bid management and basic leveling | Paid GC tier prices unpublished; sub lead subscriptions are separate | $0 for Essentials; paid tiers quote-based |
| Struvia | Takeoff through priced estimate, plus sub bid management | Plan-based estimates in your own Excel template; usage billing | No field or job-costing tools | Free to start, then usage-billed |
| PlanSwift Essential | Estimators who want a desktop takeoff and estimating seat | Pre-built assemblies; listed Auto Count, Auto Scale, Auto Bookmark | Priced per seat on an annual plan | $2,000/year, one seat, annual |
| Togal Growth | Fast automated quantity takeoff | Automated takeoffs, chat, symbol/image search | Takeoff only; per-user billing | $299 per user/month, billed yearly |
| Joist Basics | Small estimates and invoices | Low monthly cost | Not free; lists five documents/month | $10/month |
Costs are vendor-listed as of November 2026. Recheck them before buying.
Worked Example: Will the Free Plan Cap Hold Your HVAC Bid?
A free plan is only free if your project fits inside it. This test uses STACK's listed limits against a hypothetical project. It checks plan limits only, not software accuracy or quality.
Inputs: a hypothetical 420-page commercial set
Everything here is illustrative. It isn't market data, and it isn't a STACK test. Assume a commercial set of 420 total pages, with roughly 28 mechanical sheets.
Now assume the distinct HVAC measurements you'd need:
- 6 duct sizes
- 5 pipe sizes
- 12 equipment types
- 3 insulation types
- 4 damper types
- 8 diffuser, grille and register variants
- 9 other items (flex duct, sensors and thermostats, access doors, hangers and supports, sleeves)
The arithmetic and the verdict
Start with pages. The full set is 420 pages against a 300-page cap, so it's 120 pages over and doesn't fit. Upload only the 28 mechanical sheets and you're 272 pages under the cap. Pages are no longer the constraint.
Now measurements: 6 + 5 + 12 + 3 + 4 + 8 + 9 = 47. That leaves 3 of the 50 listed measurements.
Split the work by floor or by system and the count jumps well past 50. The result depends on how the tool counts a "measurement," so confirm that with the vendor.
The verdict: free works only if you trim the upload and keep the count tight. Then there's the one-active-project-per-month rule. A second bid in the same month breaks it.
How to run this test on your own bid, and when it breaks down
- Count pages. Total the set, then total the sheets you'd actually upload. Compare both to the page cap.
- List measurement categories. Write every duct size, pipe diameter, equipment type and accessory variant you'd measure. Compare the count to the measurement cap, and ask how the tool counts them.
- Count bids per month. If you bid more than one project at a time, check the active-project limit.
This test says nothing about accuracy or fit for your trade practices. If you land near a cap, make a human call or get the vendor's current terms. A plan that barely fits on a quiet month will fail in bid season.
HVAC Sub Bid Leveling: The Checklist Free Tools Don't Give You
Free tools can collect bids. They won't tell you what's missing from them. That takes a scope checklist and the discipline to run every bid against it.
The scope items that open the gap between HVAC bids
Use this list as general scoping practice. Your spec and the project's contract determine what belongs in each bid, so adapt it.
- Equipment supply versus install
- Rooftop unit curbs, plus rigging or crane
- Controls and BAS integration
- Test and balance (TAB)
- Startup and commissioning
- Ductwork insulation and fire/smoke dampers
- Condensate and drain connections
- Electrical connections and disconnects
- Permits and warranty length
Run each bid against every line. A blank is not a "no." It's a question you need answered.
Worked example: three hypothetical HVAC bids, leveled
These bids and add-ins are invented for illustration. The add-in values are estimates the GC must verify with each sub. They are not market rates.
| Line | Bid A | Bid B | Bid C |
|---|---|---|---|
| Submitted price | $412,000 | $436,000 | $471,000 |
| Controls/BAS | Excluded, +$46,000 | Excluded, +$46,000 | Included |
| TAB | Excluded, +$15,000 | Included | Included |
| Crane/rigging | Excluded, +$11,000 | Included | Included |
| Add-ins total | $72,000 | $46,000 | $0 |
| Leveled total | $484,000 | $482,000 | $471,000 |
| Rank as submitted | 1 (lowest) | 2 | 3 (highest) |
| Rank after leveling | 3 (highest) | 2 | 1 (lowest) |
The arithmetic: Bid A is $412,000 + $46,000 + $15,000 + $11,000 = $484,000. Bid B is $436,000 + $46,000 = $482,000. Bid C stays at $471,000.
As submitted, the spread is $59,000 ($471,000 − $412,000). After leveling, it's $13,000 ($484,000 − $471,000). Most of that gap was scope, not price.
Turning the checklist into a repeatable process
Put the checklist in the invitation itself, so every sub answers each line as included, excluded or by others. Mirror the same lines in your leveling sheet so bids drop into identical rows. Consistent format makes gaps visible fast.
Call the sub when a line is blank, when an exclusion is vague, or when a number looks unusually low. Don't assume an exclusion. Ask, and write the answer down. For method detail, see bid leveling in construction and the bid leveling spreadsheet guide.
HVAC vs. Mechanical Estimating Software: Match the Tool to Scope
Tool choice depends on what you actually price. Some GCs price HVAC alone. Others coordinate HVAC, plumbing and electrical sub packages on the same job, which changes what you need.
When HVAC-only tooling is enough
If you're a remodeling or light-commercial GC pricing a handful of units or an equipment replacement, HVAC estimating software focused on that scope may be all you need. If the mechanical work sits inside a larger renovation budget, remodeling estimating software may fit better. Keep the tool as simple as the scope.
When you need the full mechanical and MEP picture
Bidding HVAC, plumbing and electrical packages together means coordinating scope across trades. Who owns the condensate drain, the disconnect, or the roof penetration? That's where overlaps and gaps live.
If you need a tool that spans trades, start with our mechanical estimating software guide, then the trade pages for plumbing estimating software, electrical estimating software and electrical takeoff software.
Questions to ask any vendor before you commit
- Does it price, or only measure?
- What are the page and project limits?
- Is billing per seat or by usage?
- Can it use your own template and price book?
- What does it cost at your actual bid volume?
For the broader comparison, see our guide to the best AI estimating software for general contractors.
Where Struvia Fits: Honest Cost for an HVAC-Heavy Bid
Struvia isn't free forever, but it does have a free start. Struvia is free to try: you can run a few real plan sets before you pay anything, with no seats and no subscription. After that, billing is usage-based. Current rates are on the Struvia pricing page, and if you'd rather see it on your own job first, you can book a demo.
What the free start covers, and what comes after
The credits are spent on the work you actually run: reading the set, measuring the sheets you price, pricing the estimate and sending sub invitations. Once they're gone, you buy credits as you need them. Billing follows usage rather than an active-project count, so a second bid in the same month just uses more credits.
What Struvia does for the bid, and where it stops
Struvia handles bid packages, sub outreach, and bid leveling that normalizes scope across bids and flags gaps and exclusions. It drafts answers to subcontractor questions on a bid package. It also delivers takeoffs and estimates in your own Excel template, with your formulas intact.
Here's the contrast with takeoff-only tools, stated once. Togal does quantity takeoff only, has no cost database, and exports quantities to Excel for you to price. It's $299 per user/month, billed yearly. Struvia carries the job through to a priced estimate and bills on usage, not seats.
Struvia has no field tools: no scheduling, daily logs, job costing or accounting. It covers preconstruction through buyout. For more on this category, see our piece on free AI construction estimating tools.
Frequently Asked Questions
Is there truly free HVAC bidding software for general contractors?
Some tools list free or no-base-cost entry points, such as STACK's free account and PlanHub GC Essentials. Both come with limits. Check which of the three jobs you need covered: pricing, inviting and tracking, or leveling. This reflects vendor pages checked in November 2026.
What are the limits of STACK's free plan for HVAC takeoff?
Per STACK's pricing page, the free account, after a 7-day Pro trial, lists one active project per month, up to 300 pages, and 50 measurements per project. Confirm current terms with STACK before you plan a bid around them.
Can I level HVAC sub bids in a spreadsheet?
Yes, if you use a scope checklist and consistent line items. See our bid leveling spreadsheet guide. The limit is that every bid still needs manual review, so errors depend on your attention.
What should an HVAC bid include so I can compare it to others?
At minimum, it should state equipment supply and install, controls, test and balance, startup and commissioning, curbs and rigging, insulation, dampers, permits and warranty length. Ask each sub to mark every line included, excluded or by others. Your spec and contract determine what belongs in each bid.
Does Struvia have a free plan for HVAC bidding?
Struvia has a free start rather than a permanent free plan. The free start covers takeoff, estimating and sub invitations on a few real plan sets. After that, billing is usage-based, with no subscription or seat tiers.
Do I need separate software for HVAC, plumbing and electrical bids?
It depends on whether you price the scope yourself or manage sub bids. See the HVAC versus mechanical section above and our plumbing estimating software guide. Confirm each vendor's trade coverage directly before assuming it.
The Bottom Line on Free HVAC Bidding Software
Free HVAC bidding software exists, but "free" rarely covers pricing, invitations and leveling at once. On your next bid, run the plan-fit test against the page and measurement caps, then run the HVAC checklist against every sub proposal. The leveling step is where the real money shows up.
If you'd rather have the takeoff, estimate and leveling handled in one place, upload a plan set free on Struvia. Struvia is free to try: you can run a few real plan sets before you pay anything, and no card is needed.
*Reviewed by Weston Burnett, Co-Founder and CTO of Struvia.*
