What is the difference between a hard rule and a preference?

A hard rule is never broken by the builder: if it cannot be kept, the place stays open with the reason. A preference, such as a usual Mass, is honoured when the hard rules allow.

Does fairness mean everyone serves the same number of times?

As near as the rules allow. People with more dates away or a lower monthly limit will serve less, and the fairness report shows each person's count beside everyone else's.

What is a prime service?

The one people most want, or least want, to serve at: the main Sunday Mass, or Christmas night. Prime turns are shared out evenly on their own, on top of the total.

Why carry fairness from one quarter to the next?

Because a quarter is short. Someone who served six times last quarter and someone who served twice should not start level, so last quarter's turns count toward this one.

Fair rotation rules for parish ministries, PewRota

The hard rules

These are never broken by the builder. If one would have to be, the place stays open, with the reason in these words:

Trained for the ministry (otherwise: not trained for this ministry).
Not away that day (away that day).
One role per service (already serving at this service).
Not twice in one weekend unless the person opted in (already serving another service that weekend).
Families and pairs at the same service on a weekend (family or pair serving a different service that weekend).
A senior person in the first place of a senior-rule ministry (not flagged senior, and this is the senior place).
A minimum gap between turns, if the parish sets one (served too recently).
A personal monthly limit (at their monthly limit).

The soft costs, and their weights

Among the rotas that keep every hard rule, PewRota looks for the one with the lowest total of these costs. The weights are the engine's own:

An empty place costs 1,000,000, more than any spread of turns could save, so a place is never left empty to make the numbers prettier.
Each person's turns, carried turns included, are squared and multiplied by 10. Squaring means one extra turn for the busiest person costs more than one for the least busy.
Prime turns are squared the same way with a weight of 6.
A turn at a weekly service the person did not list as preferred costs 12.
Two turns less than 7 days apart on different weekends cost 4.
Family or pair members serving the same service take 15 off, so families serve together where they can.

Worked example: carrying fairness

Two lectors, Ana and Ben, and one lector place each Sunday in December (4 Sundays). Ana served four times last quarter; Ben did not serve. With fairness carried, PewRota gives Ana 0 and Ben 4. With carrying switched off they start level and get 2 and 2.

Worked example: a newcomer in the second quarter

Carrying turns forward has a flip side. Someone with no history, new to the parish or back from a period away, would start at zero while everyone else starts at what they served, and zero looks like a debt: the builder would load them up. PewRota starts them at the group's average instead. Take 10 lectors with two places each Sunday: the first quarter has 26 places and each serves 2 or 3 times. An eleventh lector joins for the next quarter (26 places). Starting at the average of 2.6, the newcomer gets 2 turns and the regulars 2 to 3. Counted as zero, the newcomer would have got 5. Someone who was on the list and served nothing is carried as zero, because closing a period writes a zero for them.

In the sample parish's whole quarter the spread is 6 to 9 turns per person, and the fairness report prints each person's turns, prime turns and carried turns so anyone can check.

Rules other tools use

One paid parish scheduler describes its method as filling every spot between two dates, spacing ministers fairly across the schedule, and never putting a minister in two roles on one weekend. Those are the same ideas as the hard rules and the fairness cost above; the difference here is that every rule is a setting the parish can see and change, and every open place says why.

Common mistakes

Making a preference into a hard rule, then wondering why places are open.
Letting a monthly limit of zero mean "never"; in PewRota zero means no limit.
Forgetting to close a quarter, so the next one starts everyone level.
Fixing a clash by quietly giving the same person two roles.

Try the rules on the sample parish in the rota builder, or see how they apply to altar servers.

Sources

Checked on 28 September 2026. PewRota applies your parish's own policy; it ships no liturgical rules. Where your diocese, your parish safeguarding policy or your clergy say something different, follow them.

PewRota's rota builder. Every example on this page is built by the same solver the rota builder runs, at build time, and pinned by a test.
Parish Solutions Company, Ministry Scheduler product page. Describes filling every spot between two dates, fair spacing, and never two roles on one weekend; read 2026-09-28.

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Fair rotation rules for parish ministries