What a 1 in 4 (q4) call schedule looks like, week by week.
A 1 in 4 call schedule is every fourth night. q4 means the same thing as 1 in 4: one night in every four. q3 is 1 in 3, q5 is 1 in 5, q6 is 1 in 6. A group of 3 is not on a 1 in 4. The grids are twelve weeks starting Monday, January 4, 2027. One person is on call each night. The letter is the seat, not a recommendation.
This is arithmetic. It is not a duty-hour rule, and it does not say a frequency is safe or required.
What the names mean
| Name | Also written | If one person covers every night |
|---|---|---|
| q3 | 1 in 3 | A group of 3. Each person is on every third night. |
| q4 | 1 in 4 | A group of 4. Each person is on every fourth night. |
| q5 | 1 in 5 | A group of 5. |
| q6 | 1 in 6 | A group of 6. |
If the group covers every night with exactly one person, the frequency is 1 in n, where n is the number of people. A group of 3 covering every night is q3. Calling that schedule q4 would mean someone is on call every fourth night and some nights have nobody. These grids do not leave a night empty.
A group of 6 can still run a q4, but then the average night has more than one person on call (6 divided by 4 is 1.5). This page does not draw that. It draws one person per night.
Twelve weeks, one person each night
January 4 is a Monday and is seat A. The next night is B. After the last seat, it returns to A. Twelve weeks is 84 nights. Weekend columns are Saturday and Sunday.
3 people, q3
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | A | B | C | A |
| Jan 11 | B | C | A | B | C | A | B |
| Jan 18 | C | A | B | C | A | B | C |
| Jan 25 | A | B | C | A | B | C | A |
| Feb 1 | B | C | A | B | C | A | B |
| Feb 8 | C | A | B | C | A | B | C |
| Feb 15 | A | B | C | A | B | C | A |
| Feb 22 | B | C | A | B | C | A | B |
| Mar 1 | C | A | B | C | A | B | C |
| Mar 8 | A | B | C | A | B | C | A |
| Mar 15 | B | C | A | B | C | A | B |
| Mar 22 | C | A | B | C | A | B | C |
Swipe the table if it runs past the edge of the screen.
A 28 nights, 4 Fri, 8 Sat+Sun. B 28 nights, 4 Fri, 8 Sat+Sun. C 28 nights, 4 Fri, 8 Sat+Sun.
4 people, q4
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | A | B | C |
| Jan 11 | D | A | B | C | D | A | B |
| Jan 18 | C | D | A | B | C | D | A |
| Jan 25 | B | C | D | A | B | C | D |
| Feb 1 | A | B | C | D | A | B | C |
| Feb 8 | D | A | B | C | D | A | B |
| Feb 15 | C | D | A | B | C | D | A |
| Feb 22 | B | C | D | A | B | C | D |
| Mar 1 | A | B | C | D | A | B | C |
| Mar 8 | D | A | B | C | D | A | B |
| Mar 15 | C | D | A | B | C | D | A |
| Mar 22 | B | C | D | A | B | C | D |
Swipe the table if it runs past the edge of the screen.
A 21 nights, 3 Fri, 6 Sat+Sun. B 21 nights, 3 Fri, 6 Sat+Sun. C 21 nights, 3 Fri, 6 Sat+Sun. D 21 nights, 3 Fri, 6 Sat+Sun.
5 people, q5
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | E | A | B |
| Jan 11 | C | D | E | A | B | C | D |
| Jan 18 | E | A | B | C | D | E | A |
| Jan 25 | B | C | D | E | A | B | C |
| Feb 1 | D | E | A | B | C | D | E |
| Feb 8 | A | B | C | D | E | A | B |
| Feb 15 | C | D | E | A | B | C | D |
| Feb 22 | E | A | B | C | D | E | A |
| Mar 1 | B | C | D | E | A | B | C |
| Mar 8 | D | E | A | B | C | D | E |
| Mar 15 | A | B | C | D | E | A | B |
| Mar 22 | C | D | E | A | B | C | D |
Swipe the table if it runs past the edge of the screen.
A 17 nights, 2 Fri, 5 Sat+Sun. B 17 nights, 3 Fri, 5 Sat+Sun. C 17 nights, 2 Fri, 5 Sat+Sun. D 17 nights, 2 Fri, 5 Sat+Sun. E 16 nights, 3 Fri, 4 Sat+Sun.
6 people, q6
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | E | F | A |
| Jan 11 | B | C | D | E | F | A | B |
| Jan 18 | C | D | E | F | A | B | C |
| Jan 25 | D | E | F | A | B | C | D |
| Feb 1 | E | F | A | B | C | D | E |
| Feb 8 | F | A | B | C | D | E | F |
| Feb 15 | A | B | C | D | E | F | A |
| Feb 22 | B | C | D | E | F | A | B |
| Mar 1 | C | D | E | F | A | B | C |
| Mar 8 | D | E | F | A | B | C | D |
| Mar 15 | E | F | A | B | C | D | E |
| Mar 22 | F | A | B | C | D | E | F |
Swipe the table if it runs past the edge of the screen.
A 14 nights, 2 Fri, 4 Sat+Sun. B 14 nights, 2 Fri, 4 Sat+Sun. C 14 nights, 2 Fri, 4 Sat+Sun. D 14 nights, 2 Fri, 4 Sat+Sun. E 14 nights, 2 Fri, 4 Sat+Sun. F 14 nights, 2 Fri, 4 Sat+Sun.
A post-call day off
Post-call, on this page, means the calendar day after a night of call. The person who was on call is off their usual day. It is a mark on the clinic schedule.
In the grids above, that mark does not change who is on call. With one person per night and three or more people, tomorrow’s call already belongs to the next seat. Marking today as someone else’s post-call day does not move tomorrow’s letter. Across all 84 nights, for each group size below, the on-call letter is identical whether or not you write “off” on the next day. The count of nights that would change is 0.
First week, group of 4, as a sample of the mark. “Off” is the person who was on call the night before. The on-call column is the same grid as above.
| Day | On call | Post-call day off |
|---|---|---|
| Monday, Jan 4 | A | nobody in this grid (no prior night) |
| Tuesday, Jan 5 | B | A |
| Wednesday, Jan 6 | C | B |
| Thursday, Jan 7 | D | C |
| Friday, Jan 8 | A | D |
| Saturday, Jan 9 | B | A |
| Sunday, Jan 10 | C | B |
The same holds for groups of 3, 5 and 6.
The grid does change if you add a second rule: Friday, Saturday, and Sunday go to one person, and the Monday after that Sunday is their post-call day, so they do not also take Monday. Monday then goes to the next seat. Tuesday, Wednesday, and Thursday keep walking from there, one seat per day, with no other skip. The weekend person can still land on a weekday later in the week. That is the rotation, not a limit.
Group of 3, Friday–Sunday as one person
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | A | A | A | A |
| Jan 11 | B | C | A | B | B | B | B |
| Jan 18 | C | A | B | C | C | C | C |
| Jan 25 | A | B | C | A | A | A | A |
| Feb 1 | B | C | A | B | B | B | B |
| Feb 8 | C | A | B | C | C | C | C |
| Feb 15 | A | B | C | A | A | A | A |
| Feb 22 | B | C | A | B | B | B | B |
| Mar 1 | C | A | B | C | C | C | C |
| Mar 8 | A | B | C | A | A | A | A |
| Mar 15 | B | C | A | B | B | B | B |
| Mar 22 | C | A | B | C | C | C | C |
Swipe the table if it runs past the edge of the screen.
A 28 nights, 4 Fri, 8 Sat+Sun. B 28 nights, 4 Fri, 8 Sat+Sun. C 28 nights, 4 Fri, 8 Sat+Sun.
None of the 12 Mondays differ from the plain grid. The skip did not fire: Monday’s running count was already a different person from the one who had Sunday. All 24 nights that differ are Friday, Saturday, and Sunday pulled onto one seat.
Group of 4, Friday–Sunday as one person
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | A | A | A |
| Jan 11 | B | C | D | A | B | B | B |
| Jan 18 | C | D | A | B | C | C | C |
| Jan 25 | D | A | B | C | D | D | D |
| Feb 1 | A | B | C | D | A | A | A |
| Feb 8 | B | C | D | A | B | B | B |
| Feb 15 | C | D | A | B | C | C | C |
| Feb 22 | D | A | B | C | D | D | D |
| Mar 1 | A | B | C | D | A | A | A |
| Mar 8 | B | C | D | A | B | B | B |
| Mar 15 | C | D | A | B | C | C | C |
| Mar 22 | D | A | B | C | D | D | D |
Swipe the table if it runs past the edge of the screen.
A 21 nights, 3 Fri, 6 Sat+Sun. B 21 nights, 3 Fri, 6 Sat+Sun. C 21 nights, 3 Fri, 6 Sat+Sun. D 21 nights, 3 Fri, 6 Sat+Sun.
6 of 12 Mondays differ, where the running count would have repeated Sunday’s person and the skip gave Monday to the next seat. 48 of 84 nights differ in all. The other differences are Friday, Saturday, and Sunday as one seat.
Group of 5, Friday–Sunday as one person
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | A | A | A |
| Jan 11 | E | A | B | C | B | B | B |
| Jan 18 | D | E | A | B | C | C | C |
| Jan 25 | D | E | A | B | D | D | D |
| Feb 1 | C | D | E | A | E | E | E |
| Feb 8 | B | C | D | E | A | A | A |
| Feb 15 | B | C | D | E | B | B | B |
| Feb 22 | A | B | C | D | C | C | C |
| Mar 1 | E | A | B | C | D | D | D |
| Mar 8 | E | A | B | C | E | E | E |
| Mar 15 | D | E | A | B | A | A | A |
| Mar 22 | C | D | E | A | B | B | B |
Swipe the table if it runs past the edge of the screen.
A 19 nights, 3 Fri, 6 Sat+Sun. B 19 nights, 3 Fri, 6 Sat+Sun. C 15 nights, 2 Fri, 4 Sat+Sun. D 15 nights, 2 Fri, 4 Sat+Sun. E 16 nights, 2 Fri, 4 Sat+Sun.
10 of 12 Mondays differ, where the running count would have repeated Sunday’s person and the skip gave Monday to the next seat. 68 of 84 nights differ in all. The other differences are Friday, Saturday, and Sunday as one seat.
Group of 6, Friday–Sunday as one person
| Week of | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Jan 4 | A | B | C | D | A | A | A |
| Jan 11 | E | F | A | B | B | B | B |
| Jan 18 | C | D | E | F | C | C | C |
| Jan 25 | A | B | C | D | D | D | D |
| Feb 1 | E | F | A | B | E | E | E |
| Feb 8 | C | D | E | F | F | F | F |
| Feb 15 | A | B | C | D | A | A | A |
| Feb 22 | E | F | A | B | B | B | B |
| Mar 1 | C | D | E | F | C | C | C |
| Mar 8 | A | B | C | D | D | D | D |
| Mar 15 | E | F | A | B | E | E | E |
| Mar 22 | C | D | E | F | F | F | F |
Swipe the table if it runs past the edge of the screen.
A 14 nights, 2 Fri, 4 Sat+Sun. B 14 nights, 2 Fri, 4 Sat+Sun. C 14 nights, 2 Fri, 4 Sat+Sun. D 14 nights, 2 Fri, 4 Sat+Sun. E 14 nights, 2 Fri, 4 Sat+Sun. F 14 nights, 2 Fri, 4 Sat+Sun.
6 of 12 Mondays differ, where the running count would have repeated Sunday’s person and the skip gave Monday to the next seat. 48 of 84 nights differ in all. The other differences are Friday, Saturday, and Sunday as one seat.
What this page does not cover
- No claim about sleep, safety, acuity, or how often a person should be on call. q4 is a description of the spacing, not a standard.
- No ACGME rule, no residency hour cap, and no “this meets requirements.”
- Holidays are not pulled out. A holiday that lands on your night stays your night. The holiday page is a different rule.
- Weekend days are not given extra weight here. The weekend page is where those weights are quoted.
- No days off other than the post-call day in the second grid. No one is skipped for vacation.
- The start day matters. These grids start Monday, January 4, 2027. Start on a Thursday and the weekend letters move.
When you are tired of typing the initials
Callwell builds this month from the same kind of rules: who is in the pool, which holidays count, weekend and holiday blocks before the other days. It is free for up to 3 people in the call pool, and on that plan you still place the days yourself, the way this sheet works. Auto-Build, which places them and keeps the counts, is Pro: $299/year or $29.99/month for the whole group, not per person. The annual plan includes a 3-month trial. The monthly plan does not. Viewers are free. iPhone and iPad. It stores no patient information.
Callwell is in App Store review. Until it is released, the web version is invite-only.
See how Callwell works Get the free Excel templateSources, opened November 10, 2026
- The grids are the rules in the sections above, applied to the dates on the page. There is no outside method being quoted. Checked by counting: 84 nights, one letter per night, and the weekend totals in the tables.
- callwellapp.com, fetched 08:09 GMT. The price at the bottom: Free for up to 3, Pro $299/year or $29.99/month, 3-month trial on the annual plan, no trial on the monthly plan.