An estimate delivered in Cubit format is a working file, not a printout. The measured quantities stay attached to the drawings they came off, and the rates stay attached to the quantities, so when the architect moves a wall you change one dimension and the tender total follows on its own.
That is the whole argument for it. Everything below is what that means when the file actually lands on your desk, what you can do with it, and when you should ask for a spreadsheet instead.
What Cubit estimating software actually does
Most estimating is two jobs pretending to be one. First you measure: how many square metres of blockwork, how many linear metres of skirting, how many cubic metres of concrete. Then you price: what you would charge for each of those, all in.
Traditionally those happen in different places. You measure on a printed drawing or in a takeoff package, write the numbers down, then retype them into a spreadsheet to price them. Every one of those retypes is a chance to drop a digit, and nothing in the spreadsheet remembers where the number came from.
Cubit, the estimating package from Buildsoft, puts both in one file. You do the takeoff on screen, over the drawing, and the quantity that measurement produces feeds straight into the priced estimate. The two are linked rather than copied. That link is the point — not the drawing tools, not the interface, and not the file format on its own.
What you receive when we deliver in Cubit format
A Cubit deliverable arrives as a .cbx file. Open it and you have:
- The takeoff — every measurement drawn over your drawings, colour-coded by trade, so you can see exactly what was measured and what was not
- The quantities those measurements produced, with the dimensions still visible behind them
- The priced estimate, structured to match your trades or the bill you were issued
- The rate build-ups, so you can see what sits inside each rate rather than a single figure you have to take on trust
The last one matters more than it sounds. A flat rate of £62 per square metre tells you nothing you can argue with. A rate that opens up into materials, waste, labour and margin is a rate you can defend in a tender interview, or adjust when your supplier comes back with a better price.
Why the live link matters more than the file format
Take an external wall. 140 mm blockwork, 2.7 m high, running 46 m in total.
Gross area: 2.7 × 46 = 124.2 m²
Now the deductions. Two door openings at 2.1 × 0.9, and six windows at 1.5 × 1.2:
- Doors: 2.1 × 0.9 × 2 = 3.78 m²
- Windows: 1.5 × 1.2 × 6 = 10.8 m²
- Total deductions: 14.58 m²
Net measured area: 124.2 − 14.58 = 109.62 m²
Now the rate. Round figures below to show the shape of a build-up, not our rates — use your own:
- Blocks, 10 per m² at £1.60 — £16.00 per m²
- Waste at 5% — £0.80 per m²
- Mortar, wall ties and DPC — £3.20 per m²
- Labour, gang rate — £34.00 per m²
- Sub-total — £54.00 per m²
- Overhead and margin at 15% — £8.10
- Rate entered: £62.10 per m²
109.62 m² at £62.10 is £6,807.40.
So far a spreadsheet would have done the same job. Here is where it stops doing it.
Revision B arrives and the wall goes up by 150 mm
In a spreadsheet you now go back to the drawing, remeasure the wall, work out the new gross area, redo the deductions, and retype the result. If you measured that wall in four separate runs because of the returns, you do it four times. If the same 2.7 m height also drove your plasterboard, your insulation and your painting, you do all of those too, and you hope you remembered every one.
In Cubit you change the height once, on the takeoff that produced the quantity:
- New gross: 2.85 × 46 = 131.1 m²
- Less the same 14.58 m² of openings = 116.52 m²
- 116.52 × £62.10 = £7,235.89
The tender moves by £428.49 on that wall alone, and it moves everywhere else the same dimension was used, in the time it takes to type one number. On a job with forty revisions between issue and submission, that is the difference between repricing and re-guessing.
Where Cubit sits against a spreadsheet
Neither is better in the abstract. They fail in different places.
- Traceability — in Cubit every quantity points back at the measurement that made it. In a spreadsheet a number is just a number, and six months later nobody can tell you where 109.62 came from.
- Revisions — a live takeoff absorbs them. A spreadsheet makes you find every cell the change touched.
- Sharing — everyone can open a spreadsheet. Opening a .cbx needs the software.
- Client submission — most clients and quantity surveyors want a flat priced bill, not a takeoff file. That means an export either way.
- Ad-hoc sums — for a two-line variation, a spreadsheet is faster and nobody should pretend otherwise.
Other takeoff packages solve a different half of the problem. PlanSwift takeoff software is built around assemblies, where one measured line returns the whole material list — strongest on repetitive work, where Cubit's linked estimate is strongest on jobs that keep being revised.
Measurement standards still apply
Software does not decide how work is measured. That is set by the measurement standard the job is issued under, which in the UK is NRM2 and in Australia and New Zealand is ANZSMM. Both dictate how each item is described, what gets deducted and what does not, so that two estimators measuring the same wall arrive at the same figure. The RICS new rules of measurement set out the UK rules in full.
Worth knowing, because a takeoff done to no standard at all is still a takeoff, and it will still produce a confident-looking number. It just will not match anyone else's. If you are being handed quantities, ask which standard they were measured to before you price them — the same check that applies when you read a bill of quantities.
What we need from you to work in Cubit
- Drawings, ideally PDF at a stated scale or with a dimension we can calibrate against. DWG is better where you have it.
- The revision number. Measuring Revision A when Revision C is out is the single most expensive mistake in this process.
- The specification, or enough of it to know what the blockwork actually is. "Blockwork" is not a rate.
- Your rates, if you want them used. Otherwise we build up from current supply and labour and show the workings.
- The structure you want it in — your trade headings, the client's bill, or ours.
When to ask for Excel instead
We deliver in both, and there are three good reasons to take the spreadsheet:
- You do not have a Cubit licence and are not about to buy one for a single job
- The estimate is going straight to a client or QS who works in Excel and will not open anything else
- The job is small and settled, with no revisions coming, so the live link buys you nothing
The one that catches people out is the second. If your submission has to be a priced bill in the client's own format, the Cubit file is your working document and the export is the deliverable. Ask for both, and price the tender submission knowing which one the client actually sees.
Who works this way
- Main contractors
- Subcontractors
- Developers
- Quantity surveyors
- Architects
FAQ
What is Cubit estimating software? Cubit is an estimating package that combines on-screen quantity takeoff with pricing in a single file. You measure over the drawing and the quantity feeds directly into the priced estimate, so the measurement and the rate stay linked rather than being copied between two programs.
What is a .cbx file? The native file Cubit saves to. It holds the drawings, the takeoff drawn over them, the measured quantities and the priced estimate together. Opening one needs Cubit installed; if you do not have it, ask for an Excel export alongside.
Can I edit an estimate you deliver in Cubit format? Yes. It is a live file, not a locked report. You can change rates, adjust quantities, add items and re-measure. That is the reason to take the Cubit file rather than a PDF of it.
Do I need Cubit to work with an outsourced estimator? No. We work in Cubit and deliver in whatever format suits you, including Excel bills and marked-up drawings. The software is how the work gets done, not something you have to buy into.
Is Cubit better than a spreadsheet for estimating? For anything with revisions, yes, because a dimension change flows through every quantity that used it. For a short, settled job, a spreadsheet is quicker. Most contractors end up using both.
How long does a takeoff in Cubit take? It depends on the drawings, not the software. A single-dwelling takeoff is usually days rather than weeks; poor or incomplete drawings add more time than the size of the job does.
Where to start
We prepare takeoffs and estimates in Cubit and hand over the .cbx alongside an Excel bill, so you have the working file and something you can send a client. If you want a job priced this way, send the drawings over and we will come back with a fixed fee and a turnaround date. We also produce fully measured bills of quantities and full estimates and cost plans from the same takeoff.