It does two different jobs. On plans, it measures duct runs, fittings and air devices from PDF drawings faster than counting by hand. For replacement jobs, it drafts the quote and options from your price book. It does not size the equipment or see the attic, so a person confirms tonnage and access before the price goes out.
The two jobs are sold under one label, which is why vendor pages are confusing. A takeoff tool suits tenders, new builds and remodels that come with drawings. A replacement quote builder suits changeouts, where the "drawing" is a house nobody drew. Most installers need the second kind; some need both, and a few need neither.
Two products sold under one label
| Kind of tool | Input | Output | Suits | Named on vendor pages |
|---|---|---|---|---|
| Duct takeoff from plans | PDF mechanical drawings, schedules, legends | Duct lengths by size, fittings, air devices, equipment counts, insulation | Tenders, new builds, larger remodels | iBeam, Exayard, BuildVision AI, Boon |
| Replacement quote builder | Your price book, customer details, equipment choice, site notes | A proposal with options, financing and a signature | Residential changeouts | Housecall Pro, Jobber, FieldPulse, ServiceTitan |
| Load calculation software | Floor area, glazing, insulation, air leakage, ducts | The heating and cooling load that sets equipment size | Anyone sizing equipment | ACCA lists approved Manual J software |
The third row is not an estimating tool, yet it is the one that decides whether a replacement quote is right.
What duct takeoff tools say they count
Each of these vendors describes duct work on its own pages. The claims are theirs, read in October 2026, and none is an independent test.
- iBeam. Its HVAC page says the AI "automatically measures duct lengths, sizes, and fittings", covers rectangular, spiral and flex duct, and extracts air devices and equipment from schedules and legends. It claims "99%+ accurate HVAC takeoffs in 24-72 hours" and says its QA staff review every takeoff on the done-for-you service. Its pricing page starts a do-it-yourself licence at $8,000 a year per trade (HVAC is one of three trades offered) and the done-for-you service at $25,000 a year.
- Exayard. Its HVAC page says the AI traces duct runs from air handlers and rooftop units through mains, branches and terminals, and counts diffusers, return grilles and slot registers by neck size and airflow from the diffuser schedule. Starter is $99 a user a month for about 20 sheets per seat each month, and Professional is $249 for about 50 sheets.
- BuildVision AI. Its FAQ lists HVAC among the pre-trained trades, measures ducts as linear runs, and says ambiguous items are flagged for human review before they reach the quote. It starts at $299 a month, with a 14-day trial.
- Boon. It publishes per-trade scores. Its page lists F1 of at least 0.90 for electrical, 0.85 for architectural and 0.74 for mechanical (ductwork, fittings, equipment and piping), says the scores come from real customer plan sets, and invites buyers to ask any vendor for theirs.
F1 is a score from 0 to 1 that drops both when a tool misses items and when it invents ones that are not there; 1.0 would be perfect. Boon's page does not define how it scores, so I would not turn 0.74 into a percentage. What it does show is that the vendor itself rates mechanical drawings as the harder job, below electrical and architectural. Whether that holds on your drawings is something only your own job can show. For the wider picture of what takeoff tools can and cannot do, the tutorial on AI tools for construction estimating and bid checks after the takeoff is the companion.
Test one duct job you have already built
Pick a finished job that has a drawing set and a record of what was actually installed, such as a supplier order or an as-built list.
- Write down your real quantities first, before you run anything.
- Run the drawings through the tool and note the minutes it took.
- Compare line by line. For every gap, label it: drawn but missed, never drawn, or counted twice.
- Turn the gaps into dollars with your own unit costs.
- Decide what the tool is for: a first pass, with a list of items you always count by hand.
For an invented two-storey new build with two systems, the finished sheet reads as follows.
| Item | As built | Tool result | Gap | Why |
|---|---|---|---|---|
| Rectangular trunk (ft) | 186 | 179 | -3.8% | Lost a run across a sheet break |
| Round branch, 6 to 8 in (ft) | 412 | 436 | +5.8% | One branch counted on two overlapping sheets |
| Flex duct runs (ft) | 94 | 52 | -44.7% | Flex drops drawn as a note, not a line |
| Elbows and tees (no.) | 31 | 27 | -12.9% | Offsets drawn through a wall not counted |
| Transitions (no.) | 6 | 6 | 0% | |
| Supply registers (no.) | 22 | 22 | 0% | Read from the diffuser schedule |
| Return grilles (no.) | 5 | 4 | -20.0% | One return shown on a different sheet |
| Volume dampers (no.) | 12 | 9 | -25.0% | Named in the specification, absent from the drawing |
| Duct insulation (sq ft) | 1,140 | 1,092 | -4.2% | Followed the duct totals |
Priced with illustrative unit costs, the misses add up like this: 42 ft of flex at $4.80 is $202; four fittings at $38 is $152; three dampers at $45 is $135; one return grille at $85; 7 ft of trunk at $14 is $98; and 48 sq ft of insulation at $1.60 is $77. That is $749 short. The over-counted branch, 24 ft at $6.50, adds $156 the other way, so the net miss is $593. On a duct package priced at $14,000, that is 4.2%.
The pattern matters more than the total. The tool matched what was drawn. It lost the items drawn as notes, symbols or specification lines: flex drops, dampers, offsets. Those are also the items that are easy to forget when counting by hand, so the useful result of the test is a short list of lines you always check, whichever way you count.
From quantities to a price: what a takeoff leaves out
A takeoff is a list of quantities. A price needs more lines than any drawing carries. Before you trust a tool's export as the base of a bid, check that your estimate sheet adds the following, because the export usually does not:
- hangers, straps and supports, and the labour to fit them;
- sealant, tape and mastic;
- insulation wrap and its labour, where the drawing only gives duct length;
- controls, thermostat and low-voltage wiring;
- startup, testing and balancing;
- permits, inspections and any hoisting or crane time;
- waste on sheet metal and flex;
- working-height and access conditions in each area, such as ceiling voids that need a lift.
Whether a tool adds any of these depends on the price book behind it, so ask. Exayard's pricing page, for instance, lists a price book and market prices from published cost books on its Starter plan. The lines are only as good as the rates behind them, and your own labour rates are the ones that count.
A prompt for items the specification requires but the plan omits
The test above lost its dampers because they were named in the specification and absent from the drawing. An AI assistant is good at this kind of cross-reading, provided you fence it in.
Below is the mechanical specification section for a small office refit and the list our takeoff tool produced. List every item the specification requires that is NOT in the takeoff list. Group them: (a) items usually drawn but missed, (b) items normally shown only in the specification or schedules, (c) points I should ask the designer about. Quote the clause for each item. Do not invent clauses; if you are unsure, say so.
SPECIFICATION TEXT:
[paste the clauses]
TAKEOFF LIST:
Rectangular duct 620 ft | Round duct 280 ft | Flex 140 ft | Elbows 44 | Tees 18 | Transitions 9 | Supply diffusers 26 | Return grilles 8 | Rooftop units 2An illustrative reply would list volume dampers at each branch take-off (clause 3.4.2, none in the takeoff list), flexible connectors at each rooftop unit (clause 3.6.1, none listed), and access doors at fire dampers (clause 3.7, no fire dampers in the list at all). Under the third group it might note that clause 3.9 asks for balancing by an independent agency, which is a cost question for the designer and not a takeoff item.
What you do next: open the specification and confirm each clause says what the reply claims, because assistants sometimes cite clause numbers loosely. Delete anything the text does not support. And keep a client's confidential specification out of a consumer chat account unless your agreement and the account's data settings allow it.
Replacement quote builders: what the draft gets right and wrong
For a changeout there is no takeoff. The vendors' own pages describe what the software does. Housecall Pro says it can create estimates "in seconds with AI", lets you present "good, better, best" options with templates and offer financing, and includes a price book. Jobber says its AI can draft a quote from a request using your past quotes and saved templates, and that you review it before sending. ServiceTitan's HVAC page describes multi-option proposals that convert to agreements when the customer accepts, and FieldPulse's page shows itemised options on an estimate. Prices are on the vendors' pages: Housecall Pro lists $59, $149 and $299 a month on annual billing; Jobber's auto-drafted quotes need its Connect plan or above, from $99 a month for one user billed annually, because its $29 Core plan leaves them out; and the ServiceTitan pages I read showed no prices.
What the drafts cannot know is the house. An illustrative AI draft for a 2,000 sq ft home with a 12-year-old 4-ton split system and an attic air handler reads like this.
Option 1, Standard: 4-ton single-stage split system, new coil, existing line set re-used, new pad and disconnect, standard thermostat, permit included. Option 2, Comfort: 4-ton two-stage system with the same scope plus a media filter. Option 3, Premium: 4-ton variable-speed system, smart thermostat, extended parts warranty.
Five things to fix before it goes out:
- "4-ton" was copied from the old nameplate. Nobody has calculated it.
- "Existing line set re-used" is an assumption. Someone has to check its size and condition against the new equipment, so remove the phrase until that happens.
- "Permit included" depends on your rules and your pricing. Confirm it.
- Nothing mentions the attic hatch, platform, condensate route or electrical supply, which are the things that move the price.
- "Extended parts warranty" needs the manufacturer's actual terms, including any registration step. Do not let a draft promise one.
The structure of the options is the useful part. Building three comparable packages is covered in the tutorial on good-better-best HVAC pricing with a worked replacement quote. What matters here is what the software cannot know.
Tonnage is a calculation, not the old nameplate
One ton of cooling is 12,000 BTU per hour. How many tons a house needs comes from a load calculation, which adds up heat gains and losses through walls, roof, windows, air leakage and ducts. ACCA's Manual J is the recognised residential method, and ACCA says on its page that a proper load calculation is required by building codes and most local jurisdictions, so check what your permit office asks for. It also keeps a list of approved software. Oversized equipment tends to short-cycle and handle humidity badly, which shows up as clammy rooms and short run times.
Suppose the 2,000 sq ft house above had its attic insulated and its windows replaced after the old unit went in, and the load calculation now comes back at about 32,000 BTU per hour, roughly 2.7 tons. The right question is whether a 3-ton unit suits that load, not whether to repeat 4 tons. A quote builder drafted from the nameplate would never ask. For how far AI can go with the calculation itself, the tutorial on AI and HVAC load calculations goes into the detail.
This is the expensive kind of failure, because the fix is a different unit. Picture a firm that sells the 4-ton system because the quote said so. The customer's rooms feel cool and clammy by July, the firm tests the system, and the fix is a different unit at the firm's expense. Nothing was wrong with the arithmetic in the quote. Nobody had asked for a calculation.
Access and install conditions that only a visit can settle
A person standing in the house records the conditions below. Software can store them and turn them into line items, and it cannot observe them.
| Condition | What to record | How it moves the price |
|---|---|---|
| Attic hatch and route | Hatch size against the new cabinet's width and length; boards or a walkway to the unit | A different model, a framed opening, or more labour hours |
| Service clearance | Space in front of the unit for filter, coil and panel access | A platform, or a smaller cabinet |
| Condensate | Gravity route or pump; secondary pan and float switch | Pump, pan and switch, plus drain labour |
| Line set | Length, concealed or exposed, size and condition | Re-use only after checking it against the new equipment; otherwise replace |
| Electrical | Breaker, wire and disconnect against the new nameplate | An electrician's visit or an upsized circuit |
| Gas and venting (furnaces) | Pipe size, run length, flue type | Gas and venting work |
| Outdoor unit | Pad, clearances, crane or roof access | New pad, crane hire, a platform |
| Existing ducts | Leaks, undersized returns, collapsed flex | Duct repairs and modifications |
If you quote changeouts, keep this as a one-page form the technician fills in on site and the office reads before the price leaves. The tutorial on an air conditioning survey from notes to quote shows how to turn survey notes into a proposal.
Filled in for the 2,000 sq ft house, now quoted with a 3-ton system, the form turned a tidy draft into a different price (illustrative figures).
| What the technician recorded | Line added to the quote | Price |
|---|---|---|
| Hatch 22 x 30 in against a 21 in wide air handler; no boards to the unit | Walkway boards and a two-person carry | $180 |
| No secondary pan or float switch under the air handler | Pan, float switch and drain work | $210 |
| Line set 35 ft and concealed; size matches the manufacturer's table for the new unit | Re-use after a pressure test and flush | $240 |
| Existing 40 A breaker, above the maximum on the new unit's nameplate | Breaker changed to match the nameplate | $150 |
| Outdoor pad cracked and sunk at one corner | New pad | $260 |
That is $1,040 the draft could not have known about, 10.6% on a $9,800 quote. The downsized unit is the one that catches people out: a smaller system can need a smaller breaker, and nothing in a quote drafted from the old nameplate would flag it. None of these lines needed software to find, and every one of them needed someone in the attic and at the panel with the form in hand.
What the software costs against the hours it saves
Prices vary, and not every vendor publishes them. Exayard Starter is $99 a user a month and BuildVision AI starts at $299 a month. iBeam's annual licences start at $8,000 a year for do-it-yourself HVAC takeoff and $25,000 for the done-for-you service. Boon lists an Enterprise tier from $10,000 a month and smaller one-off project packs. The quote builders run from about $59 to $299 a month at the prices above.
The takeoff sum comes first. Say a hand takeoff of a medium duct set takes three hours and the tool brings it to 45 minutes including checking and fixing. That saves 2 hours 15 minutes. At $45 an hour of loaded estimator time, that is about $101 a plan. Exayard Starter at $99 pays for itself on a single plan a month, but its allowance is about 20 sheets per seat each month. A 12-sheet mechanical set uses 60% of it, so a firm bidding three such sets a month would outgrow Starter. Count your usual sheets per set before you compare plans.
The quote builders are a different sum. Their saving is minutes per quote and fewer forgotten lines, and the cost is a subscription you may already be paying for field service software. The test is whether your drafts need fewer fixes after a month of using your price book, not what the demo promised.
Which kind of firm should trial which tool
| Firm | Trial first | Leave for later |
|---|---|---|
| Residential changeout installer quoting from site visits | A quote builder with your price book, and the one-page site form above | Duct takeoff tools, since there is no drawing to read |
| New-build duct contractor bidding from drawings | One takeoff tool on one finished job, using the test above | Premium quote-builder features |
| Light-commercial mechanical subcontractor | A takeoff tool or service with human QA, plus the specification prompt | Doing every takeoff in the owner's evenings |
If you are in the middle row, run the test on two tools rather than one, because the gap between them on your drawings is more informative than either result alone.
Questions to ask before you upload a duct plan
- How does it set scale, and what happens on a sheet with no scale bar?
- What happens at sheet breaks and overlapping views, where runs can be lost or counted twice?
- Does it read specifications and schedules, or only the drawn lines? Dampers and flex drops often live in the spec.
- Does a person review the output, and how does that change the turnaround and the price?
- What accuracy can you show on mechanical drawings, not just a headline for all trades?
- What happens to my drawings: how long they are kept and whether they are used for training.
A vendor that answers the fifth question with a number, as Boon does, is easier to test than one that answers with a slogan. A vendor that answers with a number but will not let you run your own job through first is harder to trust than either.
HVAC estimating software, answered
Can AI size an air conditioner or furnace for a quote?
Not reliably. Tonnage comes from a load calculation, such as ACCA's Manual J method, followed by equipment selection against the result. A quote builder can draft the proposal once you have chosen the equipment, but if it simply copies the size off the old nameplate it repeats whatever was installed before, right or wrong.
Is AI duct takeoff accurate enough to bid from?
Vendors claim figures such as 99% or more, and one vendor publishes lower scores for mechanical drawings than for electrical ones. Treat the number as a claim until you test it. Run one finished duct job through the tool, compare line by line, and keep a person reviewing flex runs, dampers and fittings.
Do I need takeoff software for replacement jobs?
Usually not. A like-for-like changeout has no drawing set to read. What helps there is a quote builder with your price book and a site checklist covering access, line set, condensate and electrical. Takeoff tools pay off on tenders, new builds and larger remodels where plans exist.
What should I check first on an AI duct takeoff?
Start with the items that are often drawn as notes or symbols: flex duct runs, volume dampers, offsets and fittings. Then check sheet breaks, where a run can be lost or counted twice, and confirm the scale against a dimension you know. Those are the places where a takeoff is most likely to miss or double-count an item.
Further reads
- AI Tools for HVAC Business Owners: Calls, Quotes and Maintenance Plans — The wider tool set for an HVAC firm, from calls to maintenance plans.
- AI for HVAC Contractors: Getting Answers From Manuals and Spec Sheets — Getting answers from manuals and spec sheets without guessing.
- AI Take Off Software: Trial Three Tools on One Real Plan Set — Run one past job through three AI take-off tools and score counts, scale and missed items against your manual numbers, with trial terms and prices.
- Simpro HVAC Software Pricing: What to Ask When It Is Quote-Only — How a quote-only price breaks down for a small HVAC firm, a ceiling method using published prices, a filled-in quote request and the contract terms to check.
- AI Receptionist for HVAC Companies: Route Sales Calls, Not Just Repairs — Seven call types and where each goes, phrases that signal a replacement lead, a four-question qualifier, a warm-transfer script and a worked month of calls.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: vendor pages for iBeam, Exayard, BuildVision AI, Boon, Housecall Pro, Jobber, FieldPulse and ServiceTitan, and ACCA's Manual J page. All read in October 2026.