Project unit conversions
Choose the dimension before converting SI, imperial and Thai land units
Back to calculator ↑Choose a dimension
Length, area and volume are different dimensions. Square metres cannot become metres without width; litres cannot become square metres without depth.
First decide whether the quantity is length, area or volume. Metres measure a fence edge, square metres a lawn surface, and cubic metres a soil fill. For title-deed area, choose area and rai, ngan or square wah rather than metres. Turning land area into soil bags requires an additional depth and an appropriate volume calculation.
Use base units
Multiply by the source factor to obtain metres, square metres or cubic metres, then divide by the destination factor. One cubic metre equals 1,000 litres.
Each factor refers to the SI base for its dimension: metres for length, square metres for area and cubic metres for volume. Multiply the source amount into that base, then divide by the destination factor. This keeps forward and reverse conversions consistent. One foot is 0.3048 m, one square foot is 0.09290304 m², and one cubic foot is 0.028316846592 m³.
Thai land units
One rai is four ngan, 400 square wah or 1,600 m². One ngan is 400 m²; one square wah is 4 m². The default 100 m² equals 0.0625 rai.
Thai land units are explicit: 1 rai = 1,600 m², 1 ngan = 400 m², and 1 square wah = 4 m². Therefore the default 100 m² divided by 1,600 is 0.0625 rai; divided by 4 it is 25 square wah. For volume, 1 m³ is 1,000 L. A conversion changes the numeric representation and unit, not the physical quantity.
Read precision
A foot uses the defined 0.3048 m and a square foot 0.09290304 m². Results are displayed rounded, while calculations use the full factors.
Displayed decimals are rounded for readability, while calculations use the full stored factors. For ordering materials, use the supplier’s selling unit and round whole packs with the relevant material calculator; do not prematurely round rai or square feet before pricing. Also check whether the source dimension is measured or nominal: precise conversion cannot repair an inaccurate starting measurement.
Common questions
How many square metres in one rai?
One rai equals four ngan or 400 square wah, which is 1,600 m². Check whether a deed lists rai, ngan and square wah in separate columns or one combined amount before entry.
How many litres in a cubic metre?
One cubic metre is 1,000 litres. That converts tank or soil volume, but a litre of water and a litre of bagged material do not imply the same mass.
Can square metres convert to feet?
They are different dimensions: square metres measure area, feet measure length. Choose square feet for an area conversion, or supply shape information to derive a side length.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.