Relay Exchange Zone Calculator
International zone placement and timing.
About this calculator
A clean baton exchange is about matching speeds, not just handing something off — the outgoing runner should already be moving near their top speed when the baton arrives, not standing still waiting for it. This calculator models the outgoing runner's acceleration out of the blocks with an exponential curve, v(t) = topSpeed × (1 − e^(−t/tau)), where tau is derived from how long that runner takes to reach full speed, then solves for the moment their speed matches the incoming runner's. From that match time it integrates the acceleration curve to find how far the outgoing runner has traveled, and works backward to the "go mark" — the distance behind the zone entrance where the outgoing runner should start moving so the two runners are at matching speed inside the legal exchange zone.
It accounts for the two relay formats separately: the 4x100 m has a 20 m exchange zone plus a 10 m "fly" acceleration zone before it (30 m of usable runway), while the 4x400 m has only the 20 m zone and no fly zone, and it also derates the incoming runner's speed by 10% on legs 2 and beyond of a 4x400, reflecting that 400 m runners are fatigued and decelerating by the time they reach the zone, unlike a 4x100 sprinter arriving near top speed. The output flags whether your projected exchange point actually falls inside the legal zone (an exchange outside it is a disqualification) and scores exchange quality by how closely the two runners' speeds match at the handoff — a mismatch means either a stalled outgoing runner or an incoming runner who has to slow down and give the baton up early, both costing time.
Inputs
Results
Go Mark Distance
4.23 m
≈ 2 adult heights
Figures current as of 2026. Source: World Athletics Competition and Technical Rules, Book C – C2.1 (2026 edition), Rule 24 – Relay Races (takeover zone lengths: 30m for 4x100m/4x100m Mixed/4x200m, 20m for 4x400m and longer relays)
How to Use This Calculator
- Enter Race type, Incoming runner speed, and Outgoing runner top speed.
- Set Outgoing acceleration time and Exchange number.
- Review the Go Mark Distance (m) result.
- Use Exchange Point in Zone (m) and Exchange Point % to inform your decision.
How the result changes with Incoming runner speed
| Incoming runner speed | Go Mark Distance |
|---|---|
| 5 | 0.79 m |
| 7.13 | 1.83 m |
| 12 | 11.49 m |
What each input means
- Race type
- Which relay event this exchange is for.
- Incoming runner speed
- Top speed of the incoming baton carrier.
- Outgoing runner top speed
- Top speed of the outgoing runner.
- Outgoing acceleration time
- Time for outgoing runner to reach top speed from standing.
- Exchange number
- Which exchange: 1st, 2nd, or 3rd.
What each result means
- Go Mark Distance
- Where to place check mark — distance before zone that triggers outgoing runner to start.
- Exchange Point in Zone
- Where the actual handoff should occur within the exchange zone.
- Exchange Point %
- Exchange position as percentage through the zone.
- Outgoing Speed at Exchange
- Outgoing runner's speed at the moment of baton exchange.
- Speed Match
- How well the two runners' speeds match at exchange (higher = cleaner).
- Time to Speed Match
- Time from outgoing runner start to speed match point.
- Exchange Window
- Time window where speeds are within 10% of each other.
- Exchange Window Length
- Distance window for clean exchange.
- Incoming Speed at Zone
- Incoming runner speed when entering the zone.
- Total Zone Length
- Total zone length including fly zone.
- Time Saved (fly start)
- Estimated time saved by the flying start exchange.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersRace type = 1, Incoming runner speed = 9.5, Outgoing runner top speed = 9.8, Outgoing acceleration time = 1.5 = 5 input(s) provided
- Calculate Go Mark DistanceGo Mark Distance = distIncoming - distOutgoing4.23 = 4.23
- Calculate Exchange Point in ZoneExchange Point in Zone = distOutgoing - flyZoneLength2.33 = 2.33
- Calculate Exchange Point %Exchange Point % = (exchangePointFromZoneStart / exchangeZoneLength) * 10011.7 = 11.7
Figures and sources
- World Athletics relay takeover zone dimensions (2026) — World Athletics Competition and Technical Rules, Book C – C2.1 (2026 edition), Rule 24 – Relay Races (takeover zone lengths: 30m for 4x100m/4x100m Mixed/4x200m, 20m for 4x400m and longer relays)
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What does the "Go Mark Distance" actually tell me?
It's how far behind the exchange-zone entrance the outgoing runner should start moving so that, by the time the incoming runner arrives, both are traveling at matching speed inside the legal zone. The calculator finds this by modeling the outgoing runner's acceleration curve, solving for when their speed matches the incoming runner's, and working backward from that match point to the required head start.
Why does the calculator treat 4x400 exchanges differently from 4x100 exchanges?
Under World Athletics' Competition and Technical Rules, the 4x100 relay's takeover zone is 30 m long — modeled here as a 20 m exchange zone plus a 10 m "fly" acceleration zone in front of it, letting the outgoing runner already be moving before the legal handoff area begins. The 4x400 relay's takeover zone is only 20 m long with no fly zone, and for the second exchange onward the calculator also derates the incoming runner's speed by 10%, modeling the fatigue and deceleration 400 m runners show by the time they reach the zone.
What makes an exchange come back as "Illegal" in this calculator?
The calculated handoff point has to fall within the legal exchange zone — specifically, the exchange-point-from-zone-start value must land between 0 and 20 metres. If your entered speeds and acceleration time push that calculated point outside the zone, the quality result flags it as "Illegal - outside zone!" no matter how well the runners' speeds otherwise match.
How is "Speed Match %" different from just eyeballing whether the runners look equally fast?
It's the outgoing runner's speed at exchange compared to the incoming runner's speed, expressed as a percentage. A high match (98%+) combined with a legal, well-placed handoff earns an "Excellent" rating; a large gap means either the outgoing runner hasn't accelerated enough or the incoming runner has to slow to avoid overtaking, and both cost time in the exchange.
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