Calculating Specific Gravity from CLR

If CLR (Corrected Lactometer Reading) of milk is 28, find out the specific gravity of milk:

Correct Answer: 1.028

Using the formula: Specific gravity of milk = 1 + CLR/1000

Given CLR = 28:

Specific gravity = 1 + 28/1000 = 1 + 0.028 = 1.028

Why This Formula?

The Quevenne Lactometer reads directly in CLR units (graduated 15 to 40 on the scale). To convert to the actual specific gravity (density relative to water), you use: SG = 1 + CLR/1000.

Normal Specific Gravity Values

• Cow milk: 1.028–1.030 (CLR 28–30)
• Buffalo milk: 1.030–1.032 (CLR 30–32)
• Skim milk: 1.035–1.037 (CLR 35–37)
• Colostrum: ~1.070
• Water: 1.000

Effect on Specific Gravity

• Addition of water OR addition of fat/cream: Decreases specific gravity (dilutes the denser constituents).
• Addition of skim milk OR removal of fat: Increases specific gravity.

Why Other Options Are Wrong

• 1.025 → CLR of 25; not the result for CLR 28.
• 0.28 → omits adding 1 to CLR/1000; wrong application of formula.
• 1.28 → divides CLR by 100 instead of 1000; incorrect formula application.