Illinois Prevailing Wage Calculator

Calculate total prevailing wage costs for Illinois public works projects per the Illinois Prevailing Wage Act (820 ILCS 130). Enter the trade classification, hours worked, and applicable rates to determine gross wages, fringe benefits, and total project labor costs.

Straight-time base wage per hour for the selected trade.
Health, pension, vacation, and other fringe benefits per hour worked.
Regular hours worked (up to 8 hrs/day, 40 hrs/week under Illinois law).
Hours beyond 8/day or 40/week. Paid at 1.5× base rate; fringes paid at straight-time rate.
Project duration in weeks. Total hours = (straight + overtime) × workers × weeks.

Formula

Straight-Time Wages = Straight-Time Hours × Base Rate

Overtime Wages = Overtime Hours × (Base Rate × 1.5)

Fringe Benefits = (Straight-Time Hours + Overtime Hours) × Fringe Rate

Note: Illinois law requires fringe benefits to be paid at the straight-time rate for all hours, including overtime hours.

Total Prevailing Wage Cost = Straight-Time Wages + Overtime Wages + Fringe Benefits

Effective All-In Hourly Rate = Total Prevailing Wage Cost ÷ Total Hours Worked

Total Hours = (Straight-Time Hrs + Overtime Hrs) × Workers × Weeks

Assumptions & References

  • Governed by the Illinois Prevailing Wage Act (820 ILCS 130/), which applies to all public works contracts in Illinois.
  • Overtime is defined as hours worked beyond 8 hours per day or 40 hours per week, paid at a minimum of 1.5× the base hourly rate.
  • Fringe benefits (health & welfare, pension, vacation, apprenticeship) are paid at the straight-time rate for all hours, including overtime, per standard Illinois collective bargaining agreements.
  • Prevailing wage rates are set by the Illinois Department of Labor (IDOL) and updated annually each June. Rates shown are illustrative Cook County averages — always verify current rates at labor.illinois.gov.
  • Rates vary by county; this calculator uses Cook County rates as defaults. Contractors must use the rates for the county where work is performed.
  • Public bodies must post prevailing wage rates on the job site and include them in all contracts per 820 ILCS 130/4.
  • This calculator does not include employer payroll taxes (FICA, FUTA, SUTA), workers' compensation insurance, or general liability insurance, which add approximately 25–35% to base wages.
  • Apprentices may be paid a percentage of the journeyman rate per approved apprenticeship program ratios.

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