Salary Comparison Formula
Learn how a salary comparison calculator estimates gross pay difference, net pay difference, and effective hourly earnings.
This page explains the math behind a salary comparison calculator. It shows how two annual salaries are adjusted by an estimated deductions rate and then converted into annual and hourly values so you can compare offers on a like-for-like basis.
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Net Hourly Difference
Where:
Take each annual salary, reduce it by the estimated deductions rate to get net pay, divide by annual paid hours to get net hourly pay, and then subtract option 1 from option 2.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| salaryOne - Salary option 1 | The gross annual salary for the first option before tax and deductions. | currency |
| salaryTwo - Salary option 2 | The gross annual salary for the second option before tax and deductions. | currency |
| taxRate - Estimated tax and deductions rate | The combined percentage used to estimate tax, payroll deductions, and similar regular reductions. | percent |
| hoursPerWeek - Hours worked per week | The average paid working hours per week used for both options. | hours |
| weeksPerYear - Paid weeks per year | The number of paid weeks in the year. | weeks |
Step-by-Step Calculation
Calculate annual paid hours
Multiply weekly paid hours by paid weeks per year to estimate the total number of paid hours in a year.
annualHours = hoursPerWeek * weeksPerYear
Estimate net salary for option 1
Reduce the first gross salary by the entered deductions rate to estimate annual take-home pay.
netSalaryOne = salaryOne * (1 - taxRate / 100)
Estimate net salary for option 2
Apply the same deductions rate to the second salary to estimate its annual take-home pay.
netSalaryTwo = salaryTwo * (1 - taxRate / 100)
Calculate net hourly pay for each option
Divide each estimated net annual salary by annual paid hours to convert it into net hourly pay.
hourlyNetOne = netSalaryOne / annualHours; hourlyNetTwo = netSalaryTwo / annualHours
Calculate the differences
Subtract option 1 from option 2 to see the change in gross annual pay, net annual pay, and net hourly pay.
grossDifference = salaryTwo - salaryOne; netDifference = netSalaryTwo - netSalaryOne; hourlyNetDifference = hourlyNetTwo - hourlyNetOne
Worked example: comparing two job offers
Annual paid hours
40 * 52
2,080 hours
Net salary option 1
50,000 * (1 - 25 / 100)
$37,500
Net salary option 2
60,000 * (1 - 25 / 100)
$45,000
Net hourly pay for each option
37,500 / 2,080 and 45,000 / 2,080
$18.03 per hour and $21.63 per hour
Compare the two options
60,000 - 50,000; 45,000 - 37,500; 21.63 - 18.03
$10,000 gross difference, $7,500 net difference, $3.61 net hourly difference
Final Result
With these inputs, salary option 2 is higher by $10,000 gross per year, about $7,500 in estimated annual net pay, and about $3.61 in estimated net hourly pay.
Assumptions
- ✓Both salary options use the same weekly hours and the same number of paid weeks per year.
- ✓The same combined deductions rate applies to both salary options.
- ✓The calculation is based on annual salary only and excludes benefits, bonuses, equity, and commission unless added manually.
- ✓All results are estimates and treat the entered deductions rate as constant across the full salary.
Limitations
- !Real tax systems often use brackets, thresholds, and variable deductions, so actual net pay can differ.
- !If the two roles have different hours, paid leave, or unpaid time off, the comparison may not reflect the real trade-off unless adjusted first.
- !The calculator does not measure non-cash compensation such as retirement matching, healthcare, stock awards, or allowances.
- !It does not account for location-based cost differences, commuting costs, or overtime rules.
Common Mistakes to Avoid
Entering monthly pay instead of annual salary.
Using the same weekly hours for two jobs when the schedules are actually different.
Treating the deductions rate as exact rather than a rough estimate.
Forgetting to reduce paid weeks per year when unpaid time off is expected.
Comparing salary only and ignoring recurring bonuses or major benefits.
Assuming a higher gross salary always means a much higher net hourly value.
Related Formulas
Frequently Asked Questions
What is the main formula for salary comparison?
The calculator first estimates annual net pay for each salary, then divides each by annual paid hours, and finally compares the results. The core difference formulas are salaryTwo - salaryOne, netSalaryTwo - netSalaryOne, and hourlyNetTwo - hourlyNetOne.
How do you calculate annual paid hours?
Annual paid hours are calculated by multiplying hours worked per week by paid weeks per year.
How is net salary estimated?
Net salary is estimated with gross salary multiplied by 1 minus the deductions rate divided by 100.
Why does hourly pay matter in a salary comparison?
Hourly pay helps show how much take-home value you get for each paid hour, which can make two annual salaries look more or less attractive when work time changes.
Can this formula compare part-time and full-time salaries?
Yes, but the inputs need to reflect the correct weekly hours and paid weeks so the annual hours are realistic.
What happens if both salaries use the same deductions rate?
The higher salary will still have the higher estimated net pay, but the difference after deductions will be smaller than the gross difference.
Ready to calculate your result?
Use the calculator to get instant results with your own inputs.