How to Check an AI Takeoff Before You Bid It

To check an AI takeoff before you bid it, start with coverage (what was searched and skipped), verify the scale on every measured sheet against a known dimension, review the riskiest items first, spot-check counts and areas against schedules, read the formulas and rate assumptions, and commit only what you can trace to the sheet. An AI takeoff is a proposal until you do this; it should count for nothing in your bid before then.

This article lays out that review as a repeatable checklist, with worked examples from typical commercial sheets. It applies to any automated takeoff. We use DrawScale's workflow, where Momo's output stays uncommitted until an estimator reviews it, as the reference.

Why AI takeoffs need a structured review

Automated takeoffs fail differently from manual ones. A person tends to miss things through fatigue: a skipped room, a double-clicked symbol. Software tends to fail systematically: a wrong scale on one sheet affects every quantity on it, a misread symbol legend affects every count of that type, and an unrecognized partition tag can leave a whole wall type out. A structured review targets those systematic failures first, because each one moves many numbers at once.

Step 1: Read the coverage report before any number

The first question is not "is this count right?" but "what did it look at?"

A useful coverage report lists every sheet in the set with one of three outcomes: measured, skipped with a reason, or not relevant to scope. Look for:

• Sheets you expected but do not see. If the lighting plans are E2.1 to E2.4 and only three are listed as measured, find out why before reviewing a single fixture.
• Skips with reasons you disagree with. "Enlarged plan, duplicates A-101" is a sound reason, unless the enlarged plan carries devices the overall plan does not.
• "None found" results. A classified none-found (for example, no floor boxes on E3.2 after searching the power plan) is useful information. An unexplained zero is not.

Step 2: Verify scale on every measured sheet

Scale is the single largest source of systematic error in length and area takeoff. Check it on each sheet that produced lengths or areas.

The known-dimension check

Pick a dimension printed on the sheet, ideally a long one such as the spacing between column grid lines, and measure it at the sheet's scale. On A-101, suppose grid lines 3 to 4 are dimensioned at 30'-0". If the measurement reads 29'-9", the scale is off by 0.83 percent (29.75 ÷ 30 = 0.9917). That sounds small, but it applies to every length on the sheet and is squared for areas.

Common scale traps

• Half-size prints. A sheet drawn at 1/8" = 1'-0" on a 24x36 sheet and reduced to 11x17 is no longer at 1/8". The printed scale note is now wrong by roughly half.
• Multiple scales on one sheet. An enlarged plan at 1/4" = 1'-0" beside an overall plan at 1/8" = 1'-0" needs two calibrations, one per viewport.
• "Not to scale" details. NTS details should never produce lengths or areas.
• Civil and architectural mixed. Site sheets at 1" = 20' sit next to architectural plans at 1/8" = 1'-0" in many sets.

In DrawScale, each sheet shows its scale status and how it was set, whether by Momo with its evidence or by a person. If you change a scale, every quantity measured at that scale is flagged for re-check at once rather than silently recalculated.

Step 3: Check sheet identity and revisions

Confirm that each measured sheet is the current revision. If addendum ADD-02 reissued A-102, the takeoff should be measured on the ADD-02 version, and anything measured on the superseded sheet should be flagged. Check title blocks and revision clouds on any sheet that carries a large share of the quantity.

Step 4: Review riskiest items first

Do not review top to bottom. Review in order of risk, which is roughly the product of how uncertain an item is and how much money rides on it.

Use the family-native verbs as you go: for counts, accept, adjust or reject; for areas, accept, redraw or reject; for lengths, accept, split or reclassify.

Step 5: Spot-check counts against schedules and legends

Schedules are independent evidence. Use them.

• Lighting. Compare fixture counts by type (F1, F2, F3) with the luminaire schedule, usually on E0.1 or E6.1. Schedules sometimes list quantities; if not, confirm every type in the schedule appears in the takeoff and vice versa.
• Doors. Compare the count of openings by mark with the door schedule, often on A-601. Differences usually trace to a revised plan, a deleted opening left in the schedule, or a missed tag.
• Plumbing fixtures. Compare fixture counts on P2.1 with the plumbing fixture schedule and with the restroom enlarged plans.
• Mechanical equipment. Compare RTU, VAV and diffuser counts on M2.1 with the equipment and air device schedules.

Step 6: Check areas and lengths against the drawings

For areas, compare the room-by-room ceiling or flooring area with the room finish schedule and look for rooms with no area at all. For lengths, pick two or three long partition runs and trace them yourself. If your trace and the proposal differ by more than your tolerance, find out why before accepting that item type.

Step 7: Read the formulas and assumptions

A quantity becomes a cost through formulas and rates. Open the estimate and read them. For a partition, the formula should be explicit, such as wall area = length × height, board = wall area × 2 faces × (1 + waste). The waste factor, labor production rate and unit price should each be labeled as an assumption you can confirm or change. If any number is unlabeled, treat it as unverified. Our takeoff to estimate guide walks through a full example.

Step 8: Run a miss-capture sweep

Review is not only judging what the software proposed; it is also looking for what it did not propose. Scan each key sheet for items that should be there and are not: a floor box, a fire-rated partition in a stair, a ceiling type change in a lobby. Add anything missing with the manual tools. Your additions are yours, and a later automated run will not overwrite them.

Step 9: Commit, then export

Commit is an explicit act. In DrawScale, Save to Takeoff turns reviewed proposals into committed quantities, each with a commit record, and only committed quantities reach the estimate total and the export. The Excel or CSV export carries audit columns and contains committed quantities only, and export preflight names any rows that are blocked, such as a quantity still pending scale, so nothing leaves silently wrong.

A one-page review checklist

1. Coverage report read; every expected sheet measured or skipped with a reason you accept.
2. Scale verified on each measured sheet against a known dimension.
3. Sheet revisions confirmed current; addendum sheets in place.
4. Riskiest items reviewed first.
5. Counts spot-checked against schedules and legends.
6. Two or three long runs and key areas traced by hand.
7. Formulas read; every rate and waste factor labeled and confirmed.
8. Miss-capture sweep done on key sheets.
9. Committed; export preflight clean.

For how this review applies by trade, see our pages for electrical, drywall, HVAC and plumbing contractors, or the complete takeoff guide. To see this review on your own set, request a demo.