Three-way shift swaps: a way out when one for one fails
Updated October 13, 2026 · with an example to try
In a three-way swap, one colleague takes your shift and hands one of theirs to a second colleague, who gives you one of theirs. Everyone works the same number of shifts, and each new shift is checked for overlaps and rest. It helps when the people who can take your shift have nothing you can take back.
Find a three-way swap
Example · runs in your browser; nothing you enter is sent
You want Saturday night off. Ava doesn't work nights, Ben doesn't work weekends, Cy works the day shift that ends as your night begins, and Dee already works Saturday night. Tap any day to change it (off, day, night), or change what a colleague won't work.
You
Ava
Ben
Cy
Dee
One-for-one swaps for your Sat, Nov 7 night
No one can swap with you one for one.
- Ava doesn't work nights.
- Ben doesn't work weekends.
- Cy can take it only by handing on their Sat, Nov 7 day, which doesn't fit around your shifts.
- Dee already works then.
Three-way swaps
One colleague takes your shift and hands one of theirs to a second, who gives you one of theirs.
Three-way swap
Cy and Ava
Cy takes your Sat, Nov 7 night
Cy: 84 hours off before it, 36 after
Ava takes Cy's Sat, Nov 7 day
Ava: 36 hours off before it, 60 after
You take Ava's Wed, Nov 4 day
For you: 12 hours off before it, 48 after
Bigger swaps
Looked for only while fewer than three smaller swaps work, since each extra person is one more yes you need.
Four-way swap
Cy, Ava and Ben
Cy takes your Sat, Nov 7 night
Cy: 84 hours off before it, 36 after
Ava takes Cy's Sat, Nov 7 day
Ava: 36 hours off before it, 60 after
Ben takes Ava's Wed, Nov 4 day
Ben: no shift before it, 120 hours off after
You take Ben's Thu, Nov 5 night
For you: 48 hours off before it, 12 after
Five-way swap
Cy, Ava, Ben and Dee
Cy takes your Sat, Nov 7 night
Cy: 84 hours off before it, 36 after
Ava takes Cy's Sat, Nov 7 day
Ava: 36 hours off before it, 60 after
Ben takes Ava's Wed, Nov 4 day
Ben: no shift before it, 120 hours off after
Dee takes Ben's Thu, Nov 5 night
Dee: no shift before it, 36 hours off after
You take Dee's Sun, Nov 8 night
For you: 36 hours off before it, 84 after
Made-up schedules for two weeks from Monday, November 2, 2026 (Mon, Nov 2 to Sun, Nov 15): days 07:00 to 19:00, nights 19:00 to 07:00. Every shift someone picks up is checked for overlaps and at least 11 hours off before and after it. In place of the patterns Capillary reads from a real schedule, each sample colleague can refuse one kind of shift.
In the sample, no one can swap with you one for one. Ava doesn't work nights, Ben doesn't work weekends, and Dee already works Saturday night. Cy could take your Saturday night only by handing on Cy's Saturday day shift, which starts as your Friday night ends, so you can't take it. Three people can: Cy takes your night, Ava takes Cy's day shift, and you take one of Ava's weekday day shifts. Change a day or what someone won't work, and watch the swaps change.
How a three-way swap works
- 1
A colleague takes your shift
Colleague A takes the shift you want gone, and hands on one of their own shifts. Handing it on can free the time around yours, and keeps A's number of shifts the same.
- 2
A second colleague takes theirs
Colleague B takes the shift A hands on, and hands one of their own to you.
- 3
You take the last one
You take B's shift. Each of you gives one shift and gets one.
Each hand-off has to work for the person taking the shift: no overlap with another of their shifts, and enough rest before and after it once the shift they hand on is gone. A three-way swap needs every yes, so it is only as likely as its least likely person.
Why three people find swaps two can't
Kidney exchange found the same thing. A patient with a willing donor whose kidney doesn't match can swap donors with another such pair, but two pairs often don't fit each other, while three pairs in a cycle do. Roth, Sönmez and Ünver showed that arranging three-way exchanges as well as two-way ones would substantially increase transplants, and that "larger than three-way exchanges have less impact on efficiency."
Shift swaps work the same way. The colleague free to take your shift may have nothing you can take back, and the colleague with a shift for you may be busy during yours. A third person joins the two. More in what kidney exchange teaches about shift swaps.
Bigger swaps, only when needed
Capillary's Find a swap looks for swaps of four to six people only while the smaller ones give fewer than three likely ways out, since each extra person is one more yes you need. In Capillary's simulation on made-up groups, swaps bigger than three were never needed in groups of 15 to 22 people. In groups of 6 to 10, 28 of 591 shifts had no likely one-for-one or three-way swap, and a bigger swap found a likely way out for 5 of them. Most of the hard shifts were weekend nights.
Making it happen
- 1
Ask everyone at once
It only works if all three agree. Ask the person least likely to say yes first, or ask both together. In Find a swap, Send a swap request gives each of them a link and shows you every answer; elsewhere, a message you can copy helps.
- 2
Enter it as two swaps
Most scheduling apps swap two people at a time. One person who can hold the shift in the middle for a moment, often you, enters two ordinary swaps, one with each colleague.
- 3
Follow your group's rules
Your scheduler may need to approve each swap. The swap policy guide covers what groups usually check.
Common questions
- Does a three-way swap change how many shifts anyone works?
- No. Each person gives one shift and gets one. Hours can change if the shifts differ in length.
- Who should I ask first?
- The person least likely to say yes, since the swap fails without them. Find a swap names that person on each three-way swap.
- Can my scheduling app do a three-way swap?
- Most apps swap two people at a time, so enter it as two swaps with one person in both. That person holds the middle shift for a moment. Find a swap lists the two swaps in order.
Find swaps in your own group's schedule.
Find a swap is free for clinicians. Bring in your group's schedule from its calendar link, and Capillary checks every swap for overlaps and rest for both people, puts the colleagues most likely to say yes first, and finds three-way swaps, and bigger ones where smaller swaps run short. Your copy is yours: no one in your department or hospital sees it (who can see what).
Sources
- Roth AE, Sönmez T, Ünver MU. Efficient kidney exchange: coincidence of wants in markets with compatibility-based preferences. American Economic Review 2007;97(3):828-851
- Roth AE, Sönmez T, Ünver MU. Efficient kidney exchange: coincidence of wants in a structured market. NBER Working Paper 11402, 2005
- EU Working Time Directive 2003/88/EC, Article 3 (EUR-Lex)