GPS Speedometer FAQ

A1: A speedometer that runs in your browser and reads your phone's GPS. It shows your speed on a dial with a speed limit warning, big digits and a mirrored windscreen view, and a camera view with your speed on the picture. It records trips with distance, time, average and top speed, climb and laps, draws each trip's route by speed, and has a performance timer, a speedometer check, an average speed check, a g-meter and your position as a Plus Code.

A2: Nothing. It is free, with no registration and no limit. Like every page on ZeroDataUpload, it is supported by advertising.

A3: No. Open the page in a modern browser (Chrome, Edge, Firefox, Safari or Opera) on a phone, tablet or computer. Trips, results and settings are kept in that browser, so there is nothing to sign in to.

A4: No. Your position is read only after you press Show my speed, or another button that needs your speed (Start trip, Big digits, Windscreen, Camera, Get ready and Start at the camera), and it is worked out in your browser and never sent to a server. Trips stay in this browser on this device. The page itself loads the site's ads and analytics, as every page on the site does; the Privacy Policy explains those, and your position and trips are never part of them.

A5: A speedometer needs your position, second by second, so this is the one page of zerodataupload.com that may ask for it. The rest of the site, the tool's FAQ and help pages, and anything embedded in this page, such as the ads, cannot. Your browser asks you before the first reading. If you say no, the demo drive, GPX files, saved trips and the motion-sensor g-meter still work.

A6: The page needs a connection to load; it keeps no offline copy. Once it is open, the speedometer, trips and tools keep working when mobile data drops, because the position comes from the phone's own receiver, though a first fix can take longer without data.

A7: Under an open sky a phone's GPS usually follows your speed closely, a second or so behind. Tall buildings, tunnels, car parks and a phone deep in a bag weaken the signal: the lamp above the dial turns amber, and readings the phone marks as vague are kept out of the distance and the top speed. The dial shows each reading as it comes, and Steady the dial (Settings) smooths small jumps.

A8: Car speedometers may read high but never low. The international rule for them, UN Regulation No. 39, says the speed shown must never be less than the true speed and may be up to 10 percent plus 4 km/h more. That is why the dashboard often shows a little more than the GPS. The Speedometer check, under Tools, measures your own car's difference.

A9: Grey: GPS is off. Blinking amber: the phone is still finding your position, or no reading has come for a few seconds. Amber: the latest reading is less accurate than your limit in Settings. Green: a good reading, with its accuracy in metres. Red: the browser gave no location (for example, it was not allowed). Blue: the demo drive or a replay is running.

A10: Each GPS reading comes with the phone's own estimate of its accuracy. Readings vaguer than your choice (15, 30, 60 or 150 m) are kept out of the distance and the top speed. Steady the dial blends each new speed with the last: Off shows every reading as it is, Light smooths small jumps and Strong smooths more but reacts later.

A11: Browsers give the GPS height above the WGS84 ellipsoid, a mathematical model of the Earth's shape, not above sea level, so it can differ from the height on a map. GPS height also wobbles more than position, so a climb is counted only once it rises clearly above the wobble.

A12: Laptops usually find their position from nearby Wi-Fi networks and often report no speed at all. The tool then works the speed out from the change of position over a few seconds, which reacts later and says so in a message. On a phone with GPS this is rarely needed. Try the demo drive to see the tool with real-looking readings.

A13: Tap the round sign at the top left of the dial and pick a limit, or use Settings, Speed limit warning. Above the limit, plus the margin you choose (Warn when over by), the dial turns red and you hear a chime or beeps, feel a vibration on Android phones or hear "Slow down", each as you choose; the warning repeats every 12 seconds while you stay above it. The limit is one you set yourself: road signs always apply.

A14: Like a car's meters, they count distance whenever real GPS shows you moving, with or without a recorded trip; the demo drive and replays do not count. Reset sets Trip A or Trip B back to zero, and the total can be reset under Settings, Your data. Tap the odometer under the speed to show this trip, Trip A, Trip B or the total on the dial.

A15: Distance, time since the start (with the time on the move under it), average speed while moving (with the average including stops under it), top speed and when it happened, climb and descent, the current GPS height, the acceleration in g, and how long you spent above the speed limit. Height and acceleration show even without a trip.

A16: Press Lap during a trip to close a lap and start the next; each lap shows its time, distance, average and top speed, with the fastest marked. Settings, Trips and GPS can start a new lap by itself every 1, 5 or 10 kilometres (or miles). When you save a trip with laps, a last part lap is added so the laps add up to the whole trip.

A17: Both fill the screen with your speed in large figures, a bar and your limit. Big digits is for a phone in a holder. Windscreen mirrors the figures: at night, lay the phone flat on the dashboard under the windscreen, top edge towards the glass, and read the reflection. Tap the screen for the controls (mirror direction, colour, brightness and close); the screen stays on while either is open.

A18: It shows the camera picture with your speed, the date and time, your heading and your limit on top, and can record a video or take a photo with them burned in. Position adds your coordinates to the picture. Files are saved straight to your device; nothing is uploaded, and recording stops when you close the view or the page.

A19: Show your speed, then press Start trip before you set off. Pause stops the clock at a stop and Carry on starts it again. Finish shows a summary with a name made from the time of day (you can change it); Save trip keeps it under Trips, Discard throws it away after you confirm, and Keep going returns to the trip.

A20: A trip recorded from real GPS is kept in this browser every few seconds and whenever the page is hidden. The next time you open the page it asks whether to carry on with it (the time the page was closed counts as a pause), save it as it is, or discard it.

A21: Open it under Trips to see its distance, times, averages, top speed, climb, highest and lowest points, stops and time over the limit; the route coloured by speed (with a scale and north, but no map underneath); the speed and height along the trip by distance or by time; the time at each speed; splits for each kilometre or mile; and its laps. Point at the route or a chart to see the speed and time at that spot. Replay plays it back on the dial.

A22: Yes. Under Trips, Open a GPX file reads tracks, routes or waypoints with times, up to 30 MB a file, several at once. Speed comes from the file when it has it, otherwise from the track itself. The kind of trip (on foot, bicycle, car or plane) is guessed from the speeds.

A23: From any trip: GPX (with the speed at each point, for most mapping and sports apps), KML (for Google Earth and similar), CSV (a table for spreadsheets, with the speed in km/h, mph and m/s) and GeoJSON (for mapping software). Names are written without characters those formats refuse.

A24: Under Trips, Back up all trips saves one file with every trip and your timer results. On the other device, Restore a backup reads it (up to 300 MB); trips already there are skipped. Every value in the file is checked before anything is added.

A25: Choose a test, press Get ready and follow the line above the clock: stop completely for a standing start, slow below the start speed for a rolling one, or get above the start speed for braking. The clock starts on its own and the time is worked out between GPS readings, so it is not limited to whole readings. Tick the one-foot rollout to leave out the first 30 cm, as some published times do. Use it only on a closed road or a track, never in traffic.

A26: The timer reads the speed between readings in a straight line, so with steady acceleration it finds the exact moment; in the check behind this page it matched the exact answer for steady acceleration at 1 to 10 readings a second. Real launches are less even, and a phone giving one reading a second is less exact for short times than one giving five or ten; the line under the clock says how many readings a second your phone gives. The braking test ends when the speed falls below about 1 km/h.

A27: With a passenger: hold a steady speed above 20 km/h (20 mph or 20 knots in those units) until the GPS figure says Steady, have the passenger type what the car's speedometer shows and press Compare. With each reading the tool says how far your speedometer reads high or low on average. Reading low can mean you are going faster than you think; worn or different-sized tyres can cause it.

A28: For roads with average speed cameras: press Start at the camera as you pass the first one. It shows your average so far and the distance. If you type the zone length, Keep under shows the speed that keeps your average under the limit for the rest of the zone, and never more than the limit itself, because the limit applies at every point of the road.

A29: Speeding up moves the dot up, braking down and bends left and right, with the strongest pull kept. From GPS, it is worked out from changes in speed and heading, about once a second. Motion sensor uses the phone's accelerometer for a smoother dot: hold the phone still in a mount, press Set level here while stopped, and if the dot moves the wrong way, drive a little and the tool learns the direction from GPS.

A30: It shows your position as a Plus Code, as latitude and longitude, and in degrees, minutes and seconds, with the height and accuracy, to read out on a phone call, for example to a breakdown service. A Plus Code is a short code for a spot that map apps such as Google Maps can find without a street address. Copy and Share send it only where you choose.

A31: The vehicle (it sets how far the dial goes and when you count as stopped), the speed unit (km/h, mph, knots or m/s) and height unit, how far the dial goes, the top speed needle, the limit warning (limit, margin, sound, vibration and a spoken "Slow down"), spoken updates and the voice, starting a trip when you move off, laps by distance, the accuracy limit and steadiness, keeping the screen on, and the colour of the big digits. The light or dark look follows the site's theme button.

A32: On the Drive screen, while you use the tool and are not typing: Space starts or pauses a trip once your speed is shown, L marks a lap, B shows big digits and W the windscreen view; Esc closes them. Space never asks for your location: press Show my speed for that. Elsewhere on the page these keys do what they always do.

A33: Settings, the meters and timer results are kept in this browser's storage, and trips in its own database on this device; nothing is saved on a first visit until you change something or record a trip. Delete, under Settings, Your data, removes every trip, timer result and speedometer reading after you confirm; the settings stay. Browsers can clear a site's data when a device runs low on space, so back up trips you want to keep.