What is a soot?
Soot is a traditional unit of measurement used in the Indian window and door trade. The rule is simple: 8 soot equal 1 inch. So 1 soot is one-eighth of an inch (0.125 inch, or about 3.175 mm).
A size is usually written as inches and soot together. For example, 32.5 means 32 inches plus 5 soot — that is 32 and five-eighths of an inch.
Quick rule: 8 soot = 1 inch. 1 soot = 1/8 inch = 3.175 mm.
Soot to inch to mm conversion table
| Soot | Fraction of an inch | Inches | Millimetres |
|---|---|---|---|
| 1 soot | 1/8" | 0.125" | 3.18 mm |
| 2 soot | 1/4" | 0.250" | 6.35 mm |
| 3 soot | 3/8" | 0.375" | 9.53 mm |
| 4 soot | 1/2" | 0.500" | 12.70 mm |
| 5 soot | 5/8" | 0.625" | 15.88 mm |
| 6 soot | 3/4" | 0.750" | 19.05 mm |
| 7 soot | 7/8" | 0.875" | 22.23 mm |
| 8 soot | 1" | 1.000" | 25.40 mm |
How to read a soot measurement
Take a window written as 48.5 × 60.2. Read each number as inches-dot-soot:
- 48.5 = 48 inches + 5 soot = 48 ⅝ inches ≈ 1,232 mm
- 60.2 = 60 inches + 2 soot = 60 ¼ inches ≈ 1,530 mm
The dot is not a decimal point in the usual sense — the digits after it are soot (0–7), not tenths. That distinction is exactly where conversion errors creep in.
Why soot still matters
Generations of fabricators, fitters and customers in India quote and measure in soot. It is the language of the shop floor. Software that forces everything into millimetres adds a translation step on every single measurement — and every translation is a chance to make a costly mistake.
Common soot mistakes
- Treating the digits after the dot as tenths instead of soot (reading 32.5 as 32.5 inches rather than 32 ⅝).
- Double-converting — converting soot to inches by hand, then letting software convert again, inflating cut lists.
- Rounding soot to the nearest whole inch and quietly losing fit and margin.
How AluSync handles soot
AluSync is soot-native: you enter sizes in soot exactly as your workshop measures, and the system carries the value through estimation, quoting and cutting without a manual conversion. You can also work in inches or millimetres, and price area in square feet or square metres — your choice, per estimation.
Because the soot value is stored and used directly, there is no double-conversion and no guesswork: the quote, the cutting list and the invoice all reflect the size you actually measured.