Ropani, aana, bigha and kattha
Nepal uses two traditional systems for land area. The hill system, used in Kathmandu Valley and the hill and mountain districts, counts in ropani, aana, paisa and daam. The Terai system, used across the southern plains, counts in bigha, kattha and dhur. Land ownership certificates (Lalpurja) and survey office maps record area in one of these systems, while architects, banks and municipalities usually work in square feet or square metres.
In the hill system, 1 ropani = 16 aana, 1 aana = 4 paisa and 1 paisa = 4 daam, so 1 ropani = 64 paisa = 256 daam. One aana is a square 18.5 ft on each side, 342.25 sq ft, which makes 1 ropani 5,476 sq ft (74 ft × 74 ft). In the Terai system, 1 bigha = 20 kattha and 1 kattha = 20 dhur, so 1 bigha = 400 dhur = 72,900 sq ft (270 ft × 270 ft). 1 kattha is 3,645 sq ft and 1 dhur is 182.25 sq ft.
How the conversion works
Both systems are defined exactly in square feet, so this converter first turns every input into square feet and then divides by the size of each unit. Square metres use 1 ft = 0.3048 m exactly, so 1 sq ft = 0.09290304 m² and 1 ropani = 508.737 m².
Worked example: a plot recorded as 2-4-0-0, that is 2 ropani and 4 aana. 2 × 5,476 + 4 × 342.25 = 10,952 + 1,369 = 12,321 sq ft. In square metres that is 12,321 × 0.09290304 = 1,144.66 m². In the Terai system it is 12,321 ÷ 182.25 = 67.60 dhur, which is 3 kattha and 7.6 dhur, written 0-3-7.6.
Compound results are written biggest unit first, separated by hyphens: 7-15-1-2.91 means 7 ropani, 15 aana, 1 paisa and 2.91 daam. Only the last field has decimals, rounded to two places.
Where it matters
Engineers need the plot area in square feet or square metres to check ground coverage and floor area ratio against municipal bylaws and to prepare building permit drawings. Buyers and brokers compare prices per aana or per kattha, banks value collateral from the area on the Lalpurja, and families dividing a parcel need each share written back in the local units.
Common mistakes
Mixing the hill and Terai systems: 1 ropani is about 1.5 kattha, not 1 kattha. Treating an Indian or Bangladeshi kattha as a Nepali one: the kattha varies from place to place, and Bangladesh standardises 1 katha at 720 sq ft. Reading decimal aana as paisa: 4.5 aana is 4 aana 2 paisa, not 4 aana 5 paisa. Rounding 1 ropani to 508.72 m² instead of 508.737 m², which adds up on large plots.
The area on your Lalpurja is the legal area. A fresh survey can measure something different, and a plot measured on the ground rarely matches the certificate exactly.