FSR calculator 2026: labor burden factor and worked example

Use this labor burden factor (FSR) calculator to estimate the daily cost of labor in Mexico with the same KOSAN parameters. Enter the base daily wage, review the work calendar, and adjust benefits. You will obtain the factor, the fully burdened wage and the breakdown of the employer charges considered.

Updated: 26 October 2026.

The initial reference corresponds to 2026. The values ​​in the example are editable: they do not replace your company data, your construction schedule or the conditions of a tender.

What is the labor burden factor (FSR)?

The FSR converts the tabulated salary of a workday into the labor cost considered for a unit price analysis. It relates the equivalent paid days to the days actually worked and incorporates the obligations that correspond to the analysis.

The structure of articles 190 and 191 of the Regulations of the Law of Public Works and Services Related Thereto can be expressed as FSR = (Tp/Tl) × (1 + Ps). The fully burdened wage is obtained by multiplying the tabulated salary by that factor.

• Tp: equivalent paid days during the annual period.
• Tl: days actually worked in that period.
• Ps: charges expressed as a decimal fraction. For example, 20 % is used as 0.20.

In this tool, as in KOSAN, Tp = 365 + annual bonus days + (vacation premium × vacation days). The days worked are captured directly; The calculation does not deduct vacations, breaks or holidays from Tl again.

FSR example with a $500 daily wage

You can reproduce this case with the button Reset example. It is an example of budgeting with the initial values ​​of KOSAN, not a mandatory fee for all work.

First, the equivalent paid days are obtained: 365 + 15 + (0.25 × 12) = 383. The integration factor for the SBC is 383 / 365; with daily $500, the uncapped SBC is $524.66, rounded for display only.

With these data, the effective IMSS calculated by UMA is approximately 16.936448 %. By adding INFONAVIT, retirement, risk and configured ISN, Ps is approximately 0.345251984.

FSR = (383 / 294) × (1 + 0.345251984) = 1.752488, shown to six decimal places.

Fully burdened wage = $500 × FSR = $876.24 per workday, rounded to cents. The internal operation uses the full factor, without intermediate rounding.

The ISN of 3 % and the risk premium in the example should be reviewed. In particular, the federal definition of Ps refers to social security and INFONAVIT obligations; This tool preserves the KOSAN configurable ISN. If your analysis must exclude it from Ps, enter zero and determine its treatment separately.

Why the IMSS rate changes with the wage

The automatic calculation considers a fixed contribution linked to the UMA, the excess over three UMA, contributions over the SBC and the unemployment at advanced age and old-age insurance band of the selected year. That is why two salaries with the same benefits can produce different factors.

The field IMSS captured in 17 % activates this automatic calculation, just as it happens in KOSAN. It does not mean that the IMSS result is always 17 %. If you enter a different percentage, the tool uses that manual rate and stops adjusting it by UMA.

In the breakdown you can see each component. In Advanced You can change the year, UMA, minimum reference salary, contributions, contribution ceiling and the option to absorb the employee contribution. That last option increases the employer charges; Use it only when it represents the cost assumed by the company.

To maintain consistency with the application, the configured cap is applied to IMSS components that use it in this engine. INFONAVIT, retirement and risk are kept as separate percentages without that cap; the tool warns when the SBC exceeds it.

Which project assumptions should you check?

Calendar. The initial 294 days respond to the assumption of 365 minus 52 breaks, seven holidays and 12 vacation days. Build your calendar to avoid duplicating overlapping breaks or omitting workday conditions.

Benefits. Enter vacations, annual bonus and bonus that correspond to the worker. Initial values ​​do not represent all seniorities, contracts or superior benefits.

Risk and ISN. The initial risk premium is a class V reference, not necessarily the premium from your employer registration. The ISN depends on the entity and its treatment in the budget.

Period and references. The Daily UMA of 2026 published by INEGI is $117.31 from 1 February. For a January calculation, enter the UMA for that period. The 2026 general minimum wage is $315.04 daily; Verify applicable professional area and salary. The tool uses this data to select the corresponding line from unemployment at advanced age and old-age insurance, without replacing the base salary you captured.

The years 2027–2030 include the unemployment at advanced age and old-age insurance bands incorporated into the KOSAN engine. The UMA and minimum wage for those years are not incorporated as official references in this version: you must enter them where applicable. Changing years does not convert amounts inherited from 2026 to official values ​​from another year.

How to apply a fully burdened wage in a unit price analysis

If a worker has a fully burdened wage of $876.24 per workday and an assumed productivity of 10 m² per workday, the labor cost contribution is approximately $87.62 per m². The productivity rate is illustrative: you should check it for the construction procedure and the conditions of the work area.

For a labor crew, calculate the fully burdened wage for each trade, multiply by the number of crew members and add the daily amounts. Then divide by crew productivity. Do not add charges already included in FSR a second time.

In KOSAN you can review and apply the factor to the budget labor resource. To get the same result, use the same data and settings as on this page. Also consult the unit price analysis with example to relate labor, materials and equipment.

Frequently asked questions

Do FSR and FASAR refer to the same calculation?

In practice, both abbreviations are used to refer to labor burden factor (FSR). When comparing tools, check the formula, days and employer charges – the name alone does not guarantee that they are using the same assumptions.

Why might the result differ from a factor used previously?

Compare salary, days worked, benefits, year, UMA, risk, ISN and IMSS mode. A manual IMSS rate and an automatic calculation by UMA may give different results. Also check if the other tool absorbs the employee contributions or applies different limits.

Can I use the same factor for all categories?

With automatic IMSS, the salary affects the relative contributions and the unemployment at advanced age and old-age insurance band. Calculate each category with its data before standardizing factors.

Do I need to register to use the calculator?

No. You can change the values and see the breakdown on this page. The calculations are done in your browser. To integrate them into resources and unit price analyses of a budget, meet KOSAN or consult the licenses available.