Tools · 1 Nov 2026

Sugar recovery calculator and the S-J-M formula explained

The S-J-M formula estimates the share of sucrose in a starting material that can end up in sugar, as 100 x S x (J - M) / (J x (S - M)). S is sugar purity, J is the purity of the starting juice or syrup, and M is final molasses purity.

S-J-M recovery calculator

Sugar purity (S)Starting material purity (J)Final molasses purity (M)Pol in that material, % cane (P)Unknown losses, % cane (U)Pol % sugar (Ps)

S-J-M boiling house efficiency

89.39%

Expected recovery, % cane

11.20%

Example values are shown. Use your own laboratory figures, and keep J and P on the same material. Have your chemist confirm the result.

The formula

The calculator uses this formula. F is the S-J-M yield, as a percentage of the sucrose in the starting material.

F = 100 x S x (J - M) / (J x (S - M))

Term	Meaning	Unit
F	Sucrose recoverable in sugar, per 100 of sucrose in the starting material	%
S	Purity of the sugar	%
J	Purity of the starting material, such as mixed juice, clear juice or syrup	%
M	Purity of the final molasses	%

How to enter the values

Enter purities as percentages, such as 84.
S must be above J, and J must be above M. If J equals M, the formula returns zero.
Purity is sucrose / Brix for gravity purity, and pol / Brix for apparent purity.

Where it comes from

The formula is a purity balance. Material of purity J splits into sugar of purity S and molasses of purity M. Per 100 parts of Brix in the starting material, sugar takes 100 x (J - M) / (S - M) parts. Multiply that by S / J and you get the share of sucrose that reaches sugar.

From yield to recovery on cane

F is a percentage of the sucrose in juice. Your recovery figure is a percentage of cane. Two more steps connect them.

Expected pol in sugar % cane = (P x F / 100) - U
Expected recovery % cane = expected pol in sugar % cane x 100 / Ps

Term	Meaning
P	Pol in the starting material, % cane, using the same material as J
U	Unknown losses, % cane, from your own pol balance
Ps	Pol % sugar

Worked example

This is an example with chosen numbers. They are not benchmarks. Take S = 99.8, J = 84, M = 36, P = 12.6, U = 0.10 and Ps = 99.7.

F = 100 x 99.8 x (84 - 36) / (84 x (99.8 - 36)) = 100 x 99.8 x 48 / (84 x 63.8) = 89.39%
Expected pol in sugar % cane = (12.6 x 89.39 / 100) - 0.10 = 11.163
Expected recovery % cane = 11.163 x 100 / 99.7 = 11.20

Basic boiling house recovery

Mills also use the formula with fixed values, so that seasons and mills can be compared. The ISSCT defines Basic Boiling House Recovery as the S-J-M result with S = 100, M = 28.57, and J as the purity of mixed juice.

For the example juice purity of 84, the result is 100 x 100 x (84 - 28.57) / (84 x (100 - 28.57)) = 92.38%. Compare this with your actual figure from the DMR.

Measure	How it is worked out
Actual boiling house recovery	Pol in sugar % cane x 100 / pol in mixed juice % cane
Basic boiling house recovery	S-J-M with S = 100 and M = 28.57
Reduced boiling house recovery	Actual result restated at a standard juice purity of 85

Limits of the formula

The ISSCT text says the formula gives correct results only with sucrose data. Most mill figures are pol based, so treat the result as an estimate.
Use one basis across S, J and M. Do not mix apparent and gravity purities.
Keep J and P on the same material. Clear juice has already lost pol to filter cake, and mixed juice has not.
The answer moves with M, so use a measured figure for the same period. In the example, raising M from 36 to 38 lowers F from 89.39% to 88.43%.

An estimate is not your reported recovery

The result shows what the purities suggest. Reported recovery is sugar made as a percentage of cane crushed, and FRP depends on the recovery your mill is allowed to use. See our FRP calculator for that step.

This is general information. Confirm the method with your chemist, and confirm any price use against the current notification. SugarOS, a sugar mill ERP, keeps lab readings and recovery figures in one record.

Frequently asked questions

What does S-J-M stand for?

The three purities in the formula: sugar, juice and molasses. J can also be the purity of syrup or another starting material.

Why 28.57 for molasses?

It is the fixed value the ISSCT uses for basic recovery. The ISSCT text says the Winter formula equals S-J-M with S at 100 and M at 28.57. As arithmetic, it means pol is 0.4 of non-pol, since 28.57 / 71.43 = 0.40.

Should I use actual or fixed molasses purity?

Use your measured purity for an expected recovery. Use 28.57 only for the basic recovery figure, because its purpose is comparison.

Why is my actual recovery below the S-J-M estimate?

With U at zero, the formula counts only the sucrose lost in molasses. Losses in filter cake and unknown losses also reduce what you bag. Ask your chemist to check the pol balance.

Sources

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