A taximeter is a sealed measuring device that combines two inputs, how far the cab has travelled and how much time has passed, and turns them into a fare using a stored tariff. It starts when the journey is hired, adds charges according to the council's table of fares, and displays a running total that the passenger can see. The seals matter as much as the electronics: they are what allows the council, and you, to trust the number.
What the meter actually measures
A modern meter does not measure the road itself. It counts pulses from a sensor on the vehicle, usually driven by the gearbox or wheel speed system, and converts those pulses to distance using a calibration figure set when the unit is fitted. It also has a clock, so it can charge for time as well as distance. When the cab is moving quickly, distance dominates; when it is stuck in traffic or waiting, the time element does the work. Many meters change over between the two automatically at a set speed.
Because the calculation depends on that calibration figure, anything that changes how far the car travels per wheel turn can throw the reading off. A different tyre size or a change to the final drive are the classic examples.
The main parts
| Part | What it does |
|---|---|
| Display | Shows the fare, plus status words such as "hired". Under the Cannock Chase conditions it must be legible to the passenger and capable of being illuminated |
| Speed or distance signal | Supplies the pulses used to calculate distance |
| Clock and calendar | Times waiting, and switches tariffs by hour, day or holiday on a calendar-controlled meter |
| Tariff memory | Holds the council's rates, which must be the only tariff on the meter |
| Seals | Show whether the unit or its connections have been opened |
| Printer interface | Lets a connected printer produce a receipt or a record of totals |
What the licence conditions require
The Cannock Chase conditions for hackney carriage proprietors set out in some detail what a meter must be. It has to be of an approved, calendar-controlled type, able to show the word "hired" when in use and capable of being rendered inoperable so that no fare is displayed. The word "fare" must be printed on its face so the figure is unambiguous. It has to sit where the person being carried can plainly see it at all times, with illumination available during hirings. And the unit and its fittings must be sealed in such a way that nobody can tamper with them except by breaking, damaging or permanently displacing the seals.
The same policy says the council's tariff is the only tariff permitted on the meter, and it states the maximum fare for journeys within the district. That is the basis of the rule discussed in how taxi fares are worked out.
Sealing and tampering
A seal is a simple device: a wire or tamper-evident tag that has to be broken to open the meter or alter its connection to the vehicle. If a seal is missing or damaged, an inspector can see it. Section 71 of the Local Government (Miscellaneous Provisions) Act 1976 makes it an offence to tamper with any seal on a taximeter without lawful excuse, or to alter a taximeter with intent to mislead; the same section deals with meters fitted in private hire vehicles. Drivers licensed by Cannock Chase are also told in the council's policy not to tamper, or allow anyone else to tamper, with the taximeter, its fittings or any seal.
Where a unit does have to be opened, for example to load a new tariff, it should be resealed afterwards. A broken seal with no record of authorised work is exactly what an inspector looks for.
Inspection and testing
The council can require a hackney carriage proprietor to present the vehicle and its fitted meter for inspection and testing up to three times in any twelve months, and it keeps the right to carry out spot checks as well. The same arrangement is written into private hire vehicle conditions where a meter is fitted. For private hire, the 1976 Act says a vehicle with a meter cannot be used for hire in a controlled district unless the meter has been tested and approved by the council.
Meters and the wider kit in the cab
The meter is often connected to other equipment. A printer can produce receipts and running totals, which is useful because drivers have to give a written receipt on request. Payment terminals, in-car cameras and dispatch systems may also share the vehicle's wiring or power supply. Cameras come with their own licensing rules, set out in CCTV and dashcams in taxis.
What a passenger can reasonably check
- The display is visible from the rear seat and shows a fare, not a blank screen.
- The meter starts only once you are seated and the driver is ready to move.
- The table of fares is displayed in the cab and looks current.
- The figure goes up in small, regular steps. A sudden large jump that is not explained by a tariff change or a listed extra is worth noting.
- You can read the plate and driver badge number in case you need to raise a query.
You are not expected to test the meter yourself, and drivers should not be asked to open or adjust it. If you believe a meter is wrong, record the details and report them; the route is covered in taxi complaints and lost property.
Frequently Asked Questions
Why does a taximeter have seals?
Seals show whether the meter has been opened or its connections altered. Breaking a seal without authority is evidence of interference and can be an offence.
Does a taximeter use GPS?
Traditional taximeters take their distance signal from the vehicle's own speed sensor rather than from satellite positioning. Some drivers also use satellite navigation separately to choose a route, but the legal fare comes from the approved, sealed meter.
Who reprograms and reseals a meter after a fare change?
The vehicle's owner arranges for a meter fitter to load the new tariff and reseal the unit. The council can then ask for the vehicle and meter to be presented for inspection.
Why would a meter need recalibrating?
A change in tyre size or a mechanical alteration can change how many pulses the car produces for each mile, so the meter has to be set again and sealed.
What should I do if the meter display is dark or the fare is not shown?
Ask the driver to explain before the journey continues, note the plate and badge numbers, and report it to the licensing authority. A hackney carriage on an in-district journey is expected to use a working, illuminated meter.