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How Reclaim checks its own mileage figures

A mileage app that records the wrong number is worse than one that crashes. The wrong number gets signed off and submitted. These are the four checks Reclaim runs on every recorded trip.

Why this exists

On 14 August 2026 a change to how the app promoted a buffered trip under-recorded a real commute. Twenty-one miles were driven. 17.7 were stored, split across two trips whose endpoints were motorway junctions rather than places.

Nothing noticed. Crash reporting catches crashes, not arithmetic, and the tests passed. It surfaced because the driver scrolled their own trip list that evening.

An app falling over is obvious. An app that is quietly wrong is not, and that is what these checks are for.

Miles missing between two trips

This is the shape of the August failure, and the reason the obvious check is not enough. The first trip recorded 14.2 miles between the endpoints it believed it had. For those two points, 14.2 is about right. Nothing about that trip on its own looks wrong.

What was wrong is where it ended. It stopped at a junction on the A38, and the next trip began miles away on the A380. No car teleports. The unaccounted space between consecutive trips is the lost mileage.

Reclaim measures that space and asks about it when the two trips are between half a mile and sixty miles apart, and less than four hours have passed. Outside those bounds it says nothing. Driving home from another county and starting a new trip there is not a tracking failure, and offering to add the missing 180 miles would be nonsense.

A trip that never went anywhere

A phone left in a parked car can accumulate distance without the car moving. Summed step by step, GPS noise looks like slow driving.

So this check ignores the summed distance. It uses displacement, meaning how far the trip got from its own starting point, because noise cannot inflate that. A trip that covered a mile and a half while never getting more than a few dozen yards away did not happen.

The thresholds come from real recorded trips rather than guesswork. A 1.6 mile town trip can finish less than half a mile from where it started. Short urban driving with one-way systems looks like that. Jitter looks nothing like it, and the line sits in the empty space between the two.

That gap matters here more than anywhere else. This is the check that says your trip did not happen, and a driver who believes it wrongly deletes a real journey.

Less than the shortest road route

You cannot drive less far than the shortest way between two points. A recorded distance below the road route between the trip's own endpoints is not a suspicion. It is a physical impossibility, and it means distance was lost.

It is the only check that costs a network call. It leaves slack for endpoints being a little off, and for the router picking a slightly different road than the one you drove.

Well over the shortest road route

The opposite case, and the one that used to have no verdict at all. Trips were coming in well above the road distance between their own endpoints and being stored as fine, because the other three look at something else. Jitter needs the trip to have gone almost nowhere. The route check only fires below the route. The gap check is about the space between trips.

This one asks a question rather than making a statement. A road route is a lower bound on what was driven, and three ordinary things exceed it: a detour, a one-way system, and a stop partway that you made without splitting the trip.

None of them changes your figure

Reclaim never edits a trip to make it agree with a check. Each one puts a question on the Inbox card, with the figure that prompted it, and you decide.

That is a limit we chose. A mileage claim is a tax document, and the person signing it has to be the person who chose the number. An app that silently corrects your mileage has put a figure you never saw in front of your employer or HMRC.

It also avoids a specific way of being wrong. On a trip recorded well over the road route, offering to use the road distance instead would look helpful. It would be harmful. The route is a floor, so accepting it could turn an over-claim into an under-claim in one tap.

Why the last one asks rather than tells

Coming in above the road route is ordinary, because the route is a floor. The threshold sits where measured GPS scatter sat on real driving, and no tighter. Set it tighter and it fires on honest detours. A prompt people learn to ignore is no use to anyone.

There is no clean line. A detour and a GPS wobble overlap, and a trip confirmed as a real detour can sit well above the threshold. So this check asks rather than accuses, never changes the figure, and is the one verdict that does not hold up a claim while a trip sits in your Inbox.

What is not checked

Only trips recorded by GPS are judged. A trip you typed in yourself is your own account of a journey you made. Second-guessing it would be both rude and wrong, because you may be claiming a route Reclaim would not have picked, for reasons Reclaim does not know.

For everything else the resting state is no opinion, which is not the same as fine. Reclaim tells you it checked something only when it could.