Land in Bangladesh is measured in at least four units that people use interchangeably in the same conversation, and building area in a fifth. The conversion arithmetic is simple. The problem is that records store whatever unit the last person used, so the same plot appears as 12.5 katha in one file and 20.6 decimals in another, and nobody notices they disagree by half a katha until a boundary is being surveyed.
The conversions that matter
| Unit | In square feet | In decimals | In katha |
|---|---|---|---|
| 1 chatak | 45 | 0.103 | 0.0625 |
| 1 katha | 720 | 1.65 | 1 |
| 1 bigha (20 katha) | 14,400 | 33 | 20 |
| 1 decimal (shatak) | 435.6 | 1 | 0.605 |
| 1 acre (100 decimals) | 43,560 | 100 | 60.5 |
Two figures are worth committing to memory because they catch most errors: one katha is 720 square feet, and one bigha is 33 decimals. If a document's numbers do not reconcile against those, something has been converted twice or not at all.
Where the errors actually come from
Rounding at each conversion. A plot recorded as 12.5 katha, converted to decimals, rounded, converted back, and it is no longer 12.5 katha. Over a multi-plot acquisition the drift becomes material.
Regional units. Kani, gonda, kora and kranti are still in everyday use in parts of the country, and their size is not uniform nationally. A deed written in kani in one district and read by a Dhaka office assuming another district's definition produces a real, expensive mismatch. Record the local definition against the plot rather than converting from memory.
Deed area versus surveyed area. The area in a deed and the area a surveyor measures are frequently different, sometimes because of historical drafting and sometimes because of encroachment. Both belong in the record, separately, with the source noted.
Total versus net. Land area after a road setback or an acquisition line is not what the deed says. The developable area is the number the project runs on, and it must be a separate field rather than an adjustment somebody remembers.
Why this matters commercially
Three practical consequences follow from getting units wrong:
- Land cost per square foot is wrong, so the project budget is wrong from the first line.
- The JV ratio is applied to a wrong base, which moves real money. See joint venture landowner share.
- The buildable area assumption is wrong, so the unit count in the feasibility does not survive the approved plan.
What the system should do
- Store one canonical unit for every plot, ideally square feet, with the source of the figure recorded.
- Display in whichever unit the user is working in, converting on the fly.
- Hold deed area, surveyed area and net developable area as three separate fields.
- Record the regional unit and its local definition where a document uses one.
- Never round the stored value; round only at display.
That is not sophisticated software. It is a discipline about where the truth lives, and it prevents the single most common category of expensive land error. Land acquisition records covers the rest of the record set that sits alongside it.
A worked check
A plot is described as 20 katha. The deed says 33 decimals. Are these the same?
20 katha × 720 = 14,400 sq ft. 33 decimals × 435.6 = 14,374.8 sq ft. The difference is 25.2 sq ft, or about 0.035 katha — a rounding artefact of the decimal figure, not a discrepancy. Knowing that saves an afternoon. A difference of half a katha, by contrast, is 360 square feet and is worth a survey.
What to do next
Take the three plots on your current project and check whether the area recorded in your system matches the deed, the survey and the approved plan. Where the three disagree, decide which is canonical and record why — see how plot areas and their sources are held.