What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Yes. A GPS receiver can determine its position from satellite signals without cellular service, but offline positioning, offline maps, and route guidance are separate capabilities. To measure the straight-line distance between two coordinate pairs, use the Haversine formula; it estimates distance over a spherical Earth, not distance along roads or terrain.
Does GPS work without cell service?
GPS positioning and cellular internet do different jobs. A receiver that can access satellite signals can calculate a location without a mobile-data connection. Whether it gets a usable fix depends on signal reception and receiver conditions. GPS.gov lists satellite geometry, blocked signals, atmospheric conditions, and receiver design among the factors that affect accuracy: GPS accuracy.
Offline maps are a separate matter. A location can still be determined while a map fails to appear if the map data has not been saved on the device. Download the relevant map area before going offline; Garmin describes offline map downloads for its Explore ecosystem and notes that compatible-device requirements apply: Garmin Explore.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minutePC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Position, map, and route are different capabilities
- Positioning: The receiver calculates coordinates from satellite signals.
- Map display: The device needs map data stored locally or fetched over a network.
- Routing: Turn-by-turn guidance needs route and map data; having a GPS position alone does not create an offline route.
A handheld GPS receiver or GPS device with downloadable maps may suit field use where you need a location and map without a phone connection. The distance formula below only needs coordinates; it does not require a special device.
#1 Best Overall
- Explore confidently with the reliable handheld GPS
- 2.2” sunlight-readable color display with 240 x 320 display pixels for improved readability
- Preloaded with Topo Active maps with routable roads and trails for cycling and hiking
- Support for GPS and GLONASS satellite systems allows for tracking in more challenging environments than GPS alone
- 8 GB of internal memory for map downloads plus a micro SD card slot
How do I calculate the distance between two GPS coordinates?
Haversine estimates the great-circle distance between two latitude-and-longitude points: the shortest path across a sphere’s surface. It is useful for approximate straight-line distance, but it does not calculate road distance, a planned route, or terrain-adjusted travel distance. The formula reference is secondary; for Android-specific behavior, use the platform API described below.
Haversine formula
Let the start point be latitude φ₁ and longitude λ₁, and the destination be latitude φ₂ and longitude λ₂. Convert all four angles from degrees to radians first. Then calculate:
Rank #2
- The 2.2” high-resolution display is easy to read, even in bright sunlight
- Get long battery life of up to 168 hours in standard mode and up to 1,800 hours in expedition mode with 2 field-replaceable AA batteries (not included)
- Pair with the Garmin Explore app on your compatible smartphone for wireless software updates, trip planning, Active Weather, smart notifications and additional mapping
- Get automatic cache updates from Geocaching Live, including descriptions, logs and hints when paired to the Garmin Explore app on your compatible smartphone
- Multi-GNSS support gives access to multiple global navigation satellite systems (GPS, GLONASS, Galileo, BeiDou and QZSS) to track in more challenging environments than GPS alone
a = sin²((φ₂ − φ₁) / 2) + cos(φ₁) × cos(φ₂) × sin²((λ₂ − λ₁) / 2)
c = 2 × asin(√a)
d = R × c
R is the sphere radius chosen by the implementation, and d is expressed in the same unit as R. For example, use a radius in kilometers to get a distance in kilometers. State the radius and output unit in any implementation or result you share; otherwise, the number is ambiguous.
Rank #3
- Large 2.6” sunlight-readable color display for easy viewing
- Expanded global navigation satellite systems (GNSS) and multi-band technology allow you to get optimal accuracy in challenging locations, including steep country, urban canyons and forests with dense trees
- Includes routable TopoActive mapping and federal public land map (U.S. only)
- Compatible with the Garmin Explore website and app (compatible smartphone required) to help you manage tracks, routes and waypoints and review statistics from the field
Validate inputs and interpret the result
- Keep coordinate order consistent: latitude first, longitude second.
- For Android’s documented distance method, latitude must be from −90 to 90 degrees and longitude from −180 to 180 degrees: Android Location distanceBetween API.
- Remember that a spherical Haversine result is an approximation. Android’s built-in distance method instead defines its approximate distance using the WGS84 ellipsoid, so it can differ from a spherical calculation: Android Location distanceBetween API.
- Do not infer precision from decimal places. Coordinate fixes have uncertainty, and a series of noisy fixes can overstate traveled distance if every point-to-point segment is added without considering accuracy or filtering.
How accurate is an offline GPS location?
Offline does not mean inaccurate by itself, but a displayed coordinate is still an estimate. Android describes horizontal accuracy as a radius with a 68th-percentile interpretation: it characterizes uncertainty around the reported position, not a guarantee that every fix falls within that radius. See Android’s getAccuracy() documentation.
GPS.gov gives an example of GPS-enabled smartphones typically accurate within a 4.9 m (16 ft.) radius under open sky, attributing the example to an external source. Treat it as a conditional example, not a universal result or a promise for a particular device: GPS accuracy.
Rank #4
- Compact and lightweight GPS handheld navigator boasts an anti-slip design offering a bright 3.2" screen that is sunlight readable, even in bright sunlight, plus, physical buttons provide more versatility in any conditions
- Get multi-GNSS support(GPS+GALILEO+BEIDOU+QZSS) for superior positional accuracy,so you know exactly where you are,location precision within 6 ft
- The handheld GPS navigator uses GPS technology to capture your trip or waypoint so you can guide back to your starting position
- Equip with 3-axis compass and barometric altimeter,follow your bearing on the digital compass, which provides an accurate heading even when stationary
- Hike in any weather with the water-resistant design (rated to IP66) ,Rechargeable battery can provide up to 36 hours of battery life in full charge, recharge easily with a standard USB-C cable
Should I use a last-known location or request a current fix?
On Android, getLastLocation() can return a cached position, which may be stale. Android notes that a last-known fix is quicker and minimizes app-attributed power use; when freshness matters, request a current location instead. Active location requests can require ongoing computation, so end updates when they are no longer needed and choose a frequency that fits the task. See Retrieve the current location and Optimize location use for battery.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Quick Recap
Best Value
- Rugged handheld navigator with preloaded worldwide basemap and 2.2 inch monochrome display
- WAAS enabled GPS receiver with HotFix and GLONASS support for fast positioning and a reliable signal
- Waterproof to IPX7 standards for protection against splashes, rain, etc.
- Support for paperless geocaching and Garmin spine mounting accessories. Power with two AA batteries for up to 20 hours of use (best with Polaroid AA batteries)
- See high and low elevation points or store waypoints along a track (start, finish and high/low altitude) to estimate time and distance between points
What to check before relying on GPS offline
- Satellite reception: A compatible receiver needs access to satellite signals; conditions such as blockage can affect the fix.
- Map availability: Save map data locally before losing connectivity if you need a visual map.
- Distance meaning: Haversine gives spherical straight-line distance; it is not a route or travel-distance calculation.
- Model and uncertainty: Check whether your software uses a sphere or an ellipsoid, and account for the reported accuracy rather than trusting displayed decimal places.
- Freshness and battery: Use a cached fix when speed and power matter more than freshness; request current fixes only as frequently as the task requires.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
