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GPS Tracker Mileage Accuracy Planner

Your tracker draws straight lines between its records. On a road with bends those lines cut every corner, so GPS mileage reads short. Enter your route and the reporting rule. See the gap, where it comes from and the setting that closes it.

  • Runs in your browser
  • Time, distance and heading triggers
  • Records and data per month
Your route
km

Road distance one vehicle drives on a normal day.

km/h

Typical cruising speed on the straight parts of the route.

km/h

How fast the vehicle takes the bends.

per km

Bends worth counting on an average km. City delivery: 1 to 3. Highway: under 0.3. Between 0 and 20.

°

Heading change of a typical bend. A street corner is about 90°. Between 15 and 150.

m

Radius of the bend. Street corner: 10 to 20 m. Highway curve: hundreds of metres. Between 3 and 1000.

Device reporting rule
s

Time between records on the move. Use 0 only if a distance trigger is set. Between 0 and 3600.

m

A record every N metres. Enter 0 if the rule does not use it.

°

A record when the heading changes by N degrees. Enter 0 if off. Use 0 or 5 to 180.

s

Time between records when the vehicle stands with the ignition on. Between 1 and 86400.

min

Minutes a day the vehicle stands with the ignition on. Between 0 and 1440.

m

Mean distance between two records while the vehicle does not move. Between 0 and 100.

Ignition, speed or movement filter that freezes the position when the vehicle stands.

B

Record size with protocol and network overhead. Between 1 and 2000.

Your tolerance
%

Largest difference you accept, for example in a customer contract. Between 0.1 and 50.

Typical values. Replace the interval, stopped interval, parked jump and record size with the values from your device configuration and datasheet.

Tracker distance against the roadPlanning estimate

Keep this check with the device configuration

A report with the gap, the rule comparison and the parked drift.

Mileage accuracy report

Agree the reporting rule before the customer sees the kilometres

  • The gap between tracker distance and the road
  • Corner cutting and parked drift, per day and per month
  • Reporting rules compared by error and records
  • The widest heading angle that meets your tolerance
  • The values you entered and the method

Why does a GPS tracker read fewer kilometres than the road?

A tracker does not measure distance along the road. The platform joins the records with straight lines and adds them up. On a straight road that sum is exact. When a bend falls between two records, the straight line cuts the corner and the kilometres are lost for good.

The longer the gap between records, the more each corner costs. A 30-second interval on a city route with one street corner per kilometre can lose around 6 % of the distance. A long, gentle highway loses almost nothing with the same rule.

How does the planner calculate the gap?

It drives a repeating road of straights and bends, logs a record whenever one of your triggers fires, and compares the sum of straight lines with the road. It repeats this for 24 evenly spread start points and averages them.

Records: one when time >= T, distance >= D or heading change >= H (whichever comes first)Corner cutting = 1 - (sum of straight lines between records) / (road between the same records)Arc check: records s metres apart on radius R lose 1 - sin(phi/2) / (phi/2), phi = s / RExample: R = 100 m, s = 100 m -> 1 - sin(0.5) / 0.5 = 4.1 %Sharp 90° corner, records 200 m apart: 200 x 0.188 = 37.7 m, minus 1.0 m for a 3 m radius = 36.6 m per turnParked drift = (stopped minutes x 60 / stopped interval) x jumpData per month = records per day x bytes per record x 30 / 1,000,000
  • The corner factor 0.188 for 90° is the exact average of the cut corner when the bend falls anywhere between two records. The tests of this page check the simulation against it and against the arc formula.
  • Speeds set the spacing of time-based records: cruise speed on straights, turn speed in the bend.
  • All device values are inputs or page settings that Tracom staff can update.

Which trigger closes the gap for the fewest records?

A shorter interval adds records everywhere, including on straight road where they change nothing. A heading-change trigger adds records only in the bends, where the distance is lost.

Time only

Rule A

Corner cutting
High on city routes
Records
Same on every km
Set by
Interval
Simple. Accurate only on straight routes.
Recommended

Time and heading

Rule B

Corner cutting
Small
Records
Extra only in bends
Set by
Interval and angle
Highest accuracy for each record sent.

Distance

Rule C

Corner cutting
Low at short spacing
Records
Same on every km
Set by
Metres
Steady spacing, more records on long trips.
Ask for the triggers, not only the interval

When you order or configure trackers, ask which reporting triggers the model supports and their ranges: time, distance, heading change and the stopped interval. The interval alone does not decide the mileage.

Can the tracker read more than the road?

Yes, when it stands with the ignition on and nothing freezes the position. Each parked record lands a few metres from the last one, and the platform adds those jumps as distance. Generators, pumps and vehicles that idle for hours collect the most.

A stop filter in the device or platform holds the position when the ignition is off, the speed is near zero or the motion sensor is still. With it, parked records add no distance.

How do you test the setting on a known route?

  1. Pick a measured route

    Use a loop with known length and real bends, for example a site road or a city block.

  2. Drive it with the current rule

    Note the tracker distance from the platform report for the trip.

  3. Change one trigger

    Send the new heading or interval setting and drive the same loop again.

  4. Compare and keep the record

    Write both results in the configuration sheet with the date and firmware.

Assumptions and limits

  • The road is modelled as equal bends spread evenly. Real routes mix bends, so treat the result as a planning estimate.
  • Speed is constant on straights and in bends. Braking before a bend is not modelled.
  • Satellite position error while moving is not added. On open roads it changes the sum far less than corner cutting.
  • Data volume counts records only, not heartbeats, events or video.
  • Odometers have their own tolerance. Compare with a measured route, not only with the dashboard.
A planning estimate, not a calibration

This page does not certify the distance a device records. For a contract or a dispute, test the configured device on a measured route and keep the log.

Related Tracom solution

Set the reporting rule with the device, not after the complaint

Reporting triggers and their ranges differ by model and firmware. Ask Tracom which triggers the device you plan to fit supports, then set the interval and heading angle with this planner before the rollout.

  • Triggers time, distance and heading change.
  • Stopped interval and the filter for parked records.
  • Configuration file keeps the same rule on every unit.
  • Test loop confirms the setting on your roads.
Questions

Questions about tracker mileage

Choosing a reporting rule for a new fleet? Contact Tracom.

Why is GPS tracker mileage lower than the road distance?

Mostly corner cutting. The platform joins records with straight lines, so each bend between two records shortens the trip. Longer intervals and routes with many turns lose the most.

Does a shorter reporting interval fix it?

Yes, but at a cost. It adds records on every kilometre, including straight road. A heading-change trigger usually reaches the same accuracy with far fewer records.

What is a heading-change trigger?

A device setting that sends a record when the direction of travel changes by a set angle, for example 30°. It puts records inside the bends, where distance is lost.

Can GPS mileage be higher than the real distance?

Yes. Records taken while the vehicle stands with the ignition on jump a few metres each time. Without a stop filter those jumps add up, mainly on vehicles that idle for hours.

Should I compare the tracker with the odometer?

Not on its own. Odometers have their own tolerance and tyre wear changes them. Drive a measured route and compare both with it.

What is Tracom's role here?

Tracom supplies the device, its datasheet and its configuration. This planner gives an estimate from your inputs. It does not certify the distance a device records or replace a test on your routes.

Related tools and templates

Set up the rest of the reporting rule

Get the report

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Tracom is an advanced GPS tracking device designed to enhance fleet visibility, safety, and efficiency through real-time data, intelligent alerts, and remote monitoring.

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