Part-Time Calculator

A part-time calculator helps an employee, manager or payroll planner compare a reduced schedule with a full-time reference. It can turn a weekly timetable into paid hours, calculate the full-time-equivalent percentage, estimate gross annual pay, separate additional hours from overtime, convert leave into hours and show the employer’s annual cost.

The result is a planning estimate, not a payslip or legal decision. Part-time rules differ by country, collective agreement, occupation and contract. The calculator therefore keeps its regional values editable and presents all pay as gross amounts before tax, employee social contributions, pension deductions and personal adjustments.

What the calculator can answer

The tool supports regular part-time schedules, compressed weeks, term-time work and seasonal contracts. It calculates weekly paid hours, FTE, gross pay, additional hours, overtime, leave, benefits and employer cost from one consistent set of inputs.

Build the weekly schedule accurately

The detailed schedule accepts a start time, end time and unpaid break for every day from Monday to Sunday. A day from 09:00 to 17:30 with a 30-minute unpaid break contains eight paid hours.

Paid daily hours = shift duration − unpaid break.

If the end time is earlier than or equal to the start time, the calculator treats the shift as passing through midnight. A shift from 22:00 to 06:00 with a 30-minute break therefore contains 7.5 paid hours.

Enter only unpaid breaks. Paid breaks already belong inside paid time, so do not deduct them again.

Use average hours for irregular but predictable work

The average-hours mode is useful when a worker does not follow the same timetable every week but has a reliable contractual average. Enter average paid hours and average working days per week. The calculator then estimates the average paid day:

Average day = average weekly paid hours ÷ average working days.

For highly irregular work, average hours should come from the relevant payroll or contractual reference period rather than a convenient single week.

Calculate full-time equivalent correctly

FTE compares the employee’s paid weekly hours with the full-time reference used by the employer.

FTE = part-time weekly paid hours ÷ full-time weekly reference.

There is no universal number of hours that defines full time in every country or workplace. GOV.UK notes that the United Kingdom has no specific statutory number that automatically makes a worker full- or part-time, although full-time workers commonly work 35 hours or more. The contractual comparator remains the safer input.

Choose the correct pay basis

The calculator supports three starting points because employers describe pay in different ways.

Full-time annual salary

Use this option when a job advert, pay scale or contract gives the full-time annual gross salary.

Part-time base salary = full-time salary × FTE × annualisation factor × active-year fraction.

Hourly rate

Use an hourly basis when paid hours determine the wage.

Annual base pay = hourly rate × weekly paid hours × paid weeks × active-year fraction.

Existing part-time annual salary

This mode is useful for checking an existing offer. It keeps the entered annual gross salary as the base and calculates an approximate full-time-equivalent salary:

Full-time-equivalent salary = part-time salary ÷ FTE.

The comparison can reveal whether two offers use the same full-time benchmark, but it does not prove unequal treatment. Duties, seniority, location, premiums and benefit design may differ.

Understand year-round and part-year annualisation

For a year-round salary, the calculator applies FTE and the active fraction of the year. The calculator does not reduce that salary merely because the employee takes paid leave.

For a part-year or term-time scenario, the calculator can apply:

Annualisation factor = paid weeks ÷ 52.

This is a modelling option, not a universal legal formula. Some contracts spread term-time earnings across twelve monthly payments, some include holiday pay within paid weeks, and some use separate statutory accrual methods.

UK holiday-entitlement rules for irregular-hours and part-year workers changed from 1 January 2024, and GOV.UK provides dedicated guidance and a calculator. A generic paid-weeks factor should not replace the applicable statutory method.

Separate additional hours from overtime

Part-time workers may work above their contracted hours without immediately crossing the workplace’s overtime threshold. The calculator separates the two portions.

Additional hours = extra hours that fit below the weekly overtime threshold.

Overtime hours = remaining extra hours above the threshold.

Each portion has an editable multiplier. This matters because an employer may pay additional part-time hours at the normal rate and apply a premium only above the full-time threshold.

France provides a useful example of why the distinction matters. Service-Public separates temporary contractual increases in part-time hours from statutory overtime beyond the legal 35-hour week. Collective agreements and written amendments can change how employers organise and pay those hours.

Add night, weekend or shift premiums

The premium field applies an extra percentage to a chosen number of hours:

Premium pay = premium hours × base hourly rate × premium percentage × working weeks.

Enter only the premium component, not the whole wage again. For example, a 25% night premium means the normal hourly pay is already counted elsewhere and this field adds the extra 25%.

Prorate bonuses transparently

Choose one of three bonus treatments:

• prorated by FTE and active-year fraction;
• paid as the full entered amount for the active period;
• replaced with a custom annual amount.

Bonus rules should come from the contract or scheme documentation. A performance bonus may not follow the same proportional rule as base salary.

Convert annual leave into hours

Hours are often the clearest way to compare leave when part-time employees work unequal days.

Annual leave hours = weekly paid hours × full-time leave entitlement in weeks × active-year fraction.

GOV.UK states that regular-hours part-time workers are entitled to at least 5.6 weeks of paid holiday, although that represents fewer calendar days than for someone working five days each week. German law states a minimum of 24 Werktage based on a six-day working week; proportionally, that corresponds to 20 days for a five-day week before any better contractual or collective entitlement.

France generally accrues 2.5 jours ouvrables per month of effective work, giving 30 jours ouvrables, or five weeks, for a complete year. The method used by the employer may count jours ouvrables or jours ouvrés, provided the employee does not receive less than the statutory result.

Handle public holidays separately

Public holidays are difficult to automate across 13 countries because they depend on the year, region, workplace and employee’s scheduled days. The calculator therefore uses a manual annual-hours input.

When the total leave entitlement includes public-holiday hours, the calculator deducts them from bookable leave. When they are additional, it reports them as extra paid time off.

This distinction prevents a common error: subtracting every national holiday even when some fall on days the part-time employee never works.

Review equal-treatment principles

The EU Framework Agreement on part-time work states that part-time workers should not receive less favourable employment conditions solely because they work part time, unless different treatment has an objective justification. Where appropriate, the pro-rata-temporis principle may apply.

The UK similarly protects part-time workers from less favourable treatment than comparable full-time workers. Germany’s Section 4 TzBfG contains the same basic prohibition. These principles support proportional calculations, but they do not require the same percentage reduction for every payment or benefit.

Calculate benefits and employer cost

Set benefits as prorated, fixed or custom. A fixed health plan, equipment allowance or training budget may not change with weekly hours, while a cash allowance may be proportional.

Employer on-cost = gross annual pay × entered on-cost percentage.

Employer annual cost = gross pay + benefits + employer on-cost.

The on-cost field can represent employer social contributions, pension funding, payroll taxes or another internal loading. Do not treat it as a country tax calculator.

Use the scenario comparison

The 20% to 100% FTE table helps compare reduced-hours options. It keeps the same salary benchmark, leave rule and benefit settings, so it is best used for negotiation and workforce planning rather than as a payroll forecast.

Common mistakes

• using hours at the workplace instead of paid hours;
• deducting a paid break as unpaid;
• using a national average instead of the contractual full-time reference;
• reducing a year-round salary by working weeks and then reducing it again for leave;
• treating all extra hours as overtime;
• adding the whole wage again when entering a 25% premium;
• counting public holidays that fall on non-working days;
• converting leave by days when shifts have unequal lengths;
• assuming every benefit is proportional;
• treating gross pay as take-home pay.

Frequently asked questions

Official and primary sources

• GOV.UK: Part-time workers’ rights
• GOV.UK: Holiday entitlement
• GOV.UK: Calculate holiday entitlement
• GOV.UK: Holiday reforms from 1 January 2024
• Service-Public.fr: Temps partiel d’un salarié du secteur privé
• Service-Public.fr: Durée du travail à temps plein
• Service-Public.fr: Complément d’heures
• Service-Public.fr: Heures supplémentaires
• Germany: Section 4 TzBfG
• Germany: Section 3 Bundesurlaubsgesetz
• EUR-Lex: Directive 97/81/EC on part-time work
• Swedish Work Environment Authority: Working Hours Act
• Swedish Work Environment Authority: collective agreements

Sources reviewed: 22 June 2026.