Units of measurement in the Asphalt series

Every game in the Asphalt series uses some kind of units of measurement. Some of them are real-world units like km/h (kilometers per hour) or mph (miles per hour) for a vehicle's speed; some of them are game-specific, such as vehicle ranks or a player's progress level, often measured in "stars".
Most of the real-world units are not explained in-game, as the developers probably assume that players know them from their everyday experience. This may be the case for general speed and time units, but not every player is familiar with units like N⋅m (newton-metre) or lbf⋅ft (pound-foot) for an engine's torque or the omnipresent "G" that the games use for measuring a vehicle's handling.
Sometimes the games omit units completely which leads to confusion. Asphalt Street Storm Racing, for example, always lists a vehicle's power in the imperial hp (horsepower), but torque in the metric N⋅m (newton-meter) without providing units of measurement, regardless if a player has chosen metric or imperial units in the game settings. Asphalt 9: Legends also lists pure numbers for vehicle stats so that players can guess if these are fantasy numbers or have any relation to real-world values.
== Definition ==
A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement.
For example, length is a physical quantity. The meter is a unit of length that represents a definite predetermined length. When we say 10 meters (or 10 m), we actually mean 10 times the definite predetermined length called "meter". Measurement is a process of determining how large or small a physical quantity is as compared to a basic reference quantity of the same kind.
== Systems of measurement ==
=== Overview ===
The Asphalt games usually offer the choice between the two most common systems of measurement: the metric and the imperial system.
==== Metric system ====
In the metric system, multiples and submultiples of units are related by powers of ten and their names are formed with prefixes like kilo- or centi-. This relationship is compatible with the decimal system of numbers which contributes greatly to the convenience of metric units. The name was derived from the Greek μέτρον (métron) for "measure".
The current international standard for the metric system is the International System of Units (French: Système international d'unités, hence the abbreviation SI). It is a system in which all units can be expressed in terms of seven base units: meter, kilogram, second, ampere, kelvin, mole, and candela.
==== Imperial system ====
Both imperial units and US customary units derive from earlier English units. Imperial units were mostly used in the former British Empire and the British Commonwealth, but in all these countries they have been largely supplanted by the metric system. US customary units, however, are still the main system of measurement in the United States. When a game refers to the "imperial system", it usually means the US customary system. As imperial and US customary system only differ in units that are not used in-game, these differences are of no consequence. The only exception would be the which is different in imperial and US customary systems but has been replaced with in Asphalt 4: Elite Racing.
The imperial system is based on foot, pound and second instead of meter, kilogram and second.
=== Implementation ===
==== Asphalt 9: Legends ====
* Settings: Players can set the speed unit (km/h or mph) in Settings → Sound & Display → Speed Unit. This only affects the speed display during races.
* Distances are always provided in meters, regardless of the player's personal settings.
* Vehicle stats are given in fictitious numbers without any units at all. These values are always the same, independent of personal settings. Even the value for the top speed of a vehicle does not correspond with the speed displayed in the HUD during races, neither in km/h nor in mph.
==== Asphalt Street Storm Racing ====
* Settings: Players can choose between "imperial" or "metric" directly in Options (gearwheels). This pretends to cause a complete switch between metric and imperial units everywhere in the game, but not all values are converted: Engine power is always displayed in imperial values, and torque is always displayed in metric values, regardless of the player's settings. As the upgrade section does not add units to the numbers, this can be misleading.
* Distances: The typical drag racing distance of ¼ mile (which would be 402.336 meters) is rounded to 400 meters. The game also offers ½ mi races (804.672 m) which are displayed as 800 m. The actual in-game track lengths, however, are exactly the same—the 400 and 800 meters are only chosen for a simpler display.
* Vehicle stats in the upgrade section are listed without units. They change and are recalculated according to the player's personal settings, except for the engine power (BHP) and torque values.
** The engine power (listed as BHP for brake horsepower) is always displayed in the imperial horsepower (hp) instead of the metric kilowatt (kW).
** Torque values are always displayed in the metric newton-meter (N⋅m) instead of the imperial pound-foot (lbf⋅ft).
** As weight values for stock-level cars are always integers, it can be assumed that the game was developed in metric units and converts them to imperial units on the fly. However, neither the weight nor the speed conversions seem to use the official constants of 1 lb = kg and 1 mph = km/h. Instead, calculations without rounding with wrong factors of 0.453597 for weight and 1.60926 for speed come close to the displayed in-game values.
==== Asphalt Xtreme ====
* Settings: Players can set the speed unit (km/h or mph) in Options (gearwheel) → Sound & Display → Speed Unit. This causes a complete switch between metric and imperial units everywhere in the game.
* Distances in imperial mode are displayed in yards instead of meters, but the numbers do not change. For example, a goal like "Drift distance: 600 m" will be "Drift distance: 600 yd" without any recalculations or distance changes, so length units are mere labels for the player's convenience and have no actual importance.
* Vehicle stats change and are recalculated according to the player's personal settings, except for the acceleration value.
** As the performance measure for automotive acceleration is 0 to 60 mph in imperial and 0 to 100 km/h in metric units, and as 60 mph ≠ 100 km/h, the values should be different, but they are not. It is unclear if acceleration values are provided according to metric or imperial standard.
** The conversion between km/h and mph seems to use the offical factor of 1 mph = km/h; minor differences can be explained with rounding errors.
==== Asphalt Nitro ====
* Settings: Players can set the speed unit (km/h or mph) in Settings (gearwheels) → Sound & Display → Speed Unit. This causes a complete switch between metric and imperial units everywhere in the game. All values are displayed as integers without digits.
* Distances in imperial mode are displayed in yards instead of meters, but the numbers do not change. For example, a goal like "Drift Distance: 4,000 m" will be "Drift Distance: 4,000 yd" without any any recalculations or distance changes, so length units are mere labels for the player's convenience and have no actual importance.
* Vehicle stats change and are recalculated according to the player's personal settings, except for the acceleration value.
** As the performance measure for automotive acceleration is 0 to 60 mph in imperial and 0 to 100 km/h in metric units, and as 60 mph ≠ 100 km/h, the values should be different, but they are not. As the game only displays integers, it is difficult to say whether it shows the metric or imperial acceleration.
** The conversion between km/h and mph seems to use the offical factor of 1 mph = km/h, displayed in integers with digits cut off and not rounded. A few test calculations delivered exactly the values displayed in-game if km/h was converted to mph and the digits cut off.
==== Asphalt Overdrive ====
* Settings: Players can set the speed unit (km/h or mph) in Options → Settings → Speed Settings. This causes a complete switch between metric and imperial units everywhere in the game.
* Distances in imperial mode are displayed in yards instead of meters and converted exactly. A mission like "Outrun the cops for 3,300 meters" will be "Outrun the cops for 3,608 yards". Imperial values are not rounded; the digits are simply cut off. As the metric values in missions are always multiples of 100 while the imperial ones are not, it is probable that the game was completely developed in metric units and converts them to imperial units on the fly.
* Vehicle stats change and are recalculated according to the player's personal settings, except for the acceleration value.
** As the game is apparently based on metric units, it is probable that the acceleration value denotes the 0 to 100 km/h time which is not converted to 0 to 60 mph.
** All speed values are based on metric units and are converted to imperial mph according to the player's settings. As with length units, only integers are shown, with the digits being cut instead of being rounded.
==== Asphalt 8: Airborne ====
* Settings: Players can set the speed unit (km/h or mph) in Settings (gearwheel) → Sound & Display → Speed Unit. This causes a complete switch between metric and imperial units everywhere in the game.
* Distances in imperial mode are displayed in yards instead of meters, but the numbers do not change. For example, a quest like "Drive 1,000 meters using nitro!" will be "Drive 1,000 yards using nitro!" without any any recalculations or distance changes, so length units are mere labels for the player's convenience and have no actual importance.
* Vehicle stats change and are recalculated according to the player's personal settings, except for the acceleration value.
** As the performance measure for automotive acceleration is 0 to 60 mph in imperial and 0 to 100 km/h in metric units, and as 60 mph ≠ 100 km/h, the values should be different, but they are not. The acceleration times of in-game vehicles at stock level often correspond with the metric values of their real-world counterpart, so it is probable that the game provides the metric acceleration value for both settings.
** Nearly all imperial or all metric in-game values of speed and nitro are wrong. They almost never correspond with the official factor of 1 mph = km/h but differ by 0.1 to 0.5 km/h. The game does not even use a constant conversion factor, and the differences cannot be reproduced with rounding errors either. It seems that the game uses fixed tables for metric and imperial speeds that were once (wrongly) stored and never recalculated.
==== Asphalt 3: Street Rules ====
* The vehicle stats show a mixture of metric and imperial units.
** Metric: Speed is given in km/h, acceleration and braking time are named 0–100/100–0 and given in seconds.
** Imperial: Weight is given in pounds, and power in horsepower.
** A property named control is given in "bps". This may be an early equivalent of handling, but the meaning of "bps" remains unclear.
== Units ==
The following table gives an overview of the units of measurement used in the Asphalt games, along with their corresponding units in the metric or imperial system, also if only one system is used in-game. Base units like the gram (g) are listed as well if derived units like the kilogram (kg) are used.
* Bold numbers are exact; others are rounded to 3 digits.
* Numbers greater than 999 are written without decimal separator (,) to avoid confusion with the point (.).
* The unit g for the g-force (acceleration due to gravity) is written in italics to avoid confusion with the gram (g).
* In case of different spellings in American and British English, the American spelling is used, namely for liter (litre), meter (metre) and their derivations.
Name 	Symbol 	System 	Unit of 	Conversion 	Usage
Foot 	ft 	Imperial	Length 	1 ft = 0.3048 m 	Only indirectly as part of for torque in Asphalt Streetstorm.
g-force 	g 	Both 	Acceleration	1 g = 9.80665 m/s²1 g = 32.174 ft/s² 	Used as G's, Gs, G and g in almost all games that measure handling. "G's" and "Gs" are always meant as plurals (multiples of G), not as "G times second" (G⋅s). Besides, the upper case usage "G" is wrong (see handling for details).
Gallon (imperial) 	gal 	Imperial	Volume 	1 gal = 4.54609 l 	Unused, would be the imperial equivalent to in Asphalt 4 which measures Nitro by volume instead of speed gain.
Gallon (US customary)	gal 	US 	Volume 	1 gal = 3.785411784 l 	Unused, would be the US customary equivalent to in Asphalt 4 which measures Nitro by volume instead of speed gain.
Gram 	g 	Metric 	Mass 	(Base) 	Only indirectly as part of for weight in Asphalt Streetstorm, 3, 2 and 1.
Horsepower 	hp 	Imperial	Power 	1 hp = kW1 hp = PS 	Used for engine power as BHP (brake horsepower) in Asphalt Streetstorm (without unit), Engine in Asphalt 4 and 2 (with unit) and Power in Asphalt 3 (with unit).
Hour 	h 	Both 	Time 	1 h = 60 s 	Timers in most Asphalt games.
Kilogram 	kg 	Metric 	Mass 	1 kg = 1000 g1 kg= lb 	Metric vehicle weight in Asphalt Streetstorm, 3, 2 and 1.
Kilometer 	km 	Metric 	Length 	1 km = 1000 m1 km = 0.621 mi1 km = 1093.613 yd	Only indirectly as part of for metric speed in most Asphalt games.
 	km/h 	Metric 	Speed 	1 km/h = mph 	Metric unit for speed in most Asphalt games.
Kilowatt 	kW 	Metric 	Power 	1 kW = 1000 W1 kW = hp1 kW = PS 	Unused, would be the metric equivalent to in Asphalt Streetstorm, 4, 3 and 2 which all use horsepower, regardless of personal settings.
Liter 	l, L 	Metric 	Volume 	1 l = 0,220 gal (imp)1 l = 0,264 gal (US) 	Used in Asphalt 4 which measures Nitro by volume instead of speed gain.
Meter 	m 	Metric 	Length 	1 m = 1.094 yd1 m = 3.281 ft 	Metric unit for distances in most Asphalt games.
 	m/s² 	Metric 	Acceleration	1 m/s² = 0.102 g 	Only indirectly as part of the unit in almost all games that measure handling.
Mile 	mi 	Imperial	Length 	1 mi = 5280 ft1 mi = 1760 yd1 mi = 1.609344 km	Only indirectly as part of for imperial speed in most Asphalt games.
Miles per hour 	mph 	Imperial	Speed 	1 mph = km/h 	Imperial unit for speed in most Asphalt games.
Newton 	N 	Metric 	Force 	1 N = 0.225 lbf 	Only indirectly as part of for torque in Asphalt Streetstorm.
Newton-meter 	N⋅m 	Metric 	Torque 	1 N⋅m = lbf⋅ft 	Used for torque in both metric and imperial mode of Asphalt Streetstorm, regardless of personal settings. Displayed without unit.
Pferdestärke 	PS 	Metric 	Power 	1 PS = kW1 PS = hp 	Unused, would be an alternative for the metric which is also unused by Asphalt Streetstorm, 4, 3 and 2 in favor of the imperial .
Pound (avoirdupois) 	lb 	Imperial	Mass 	1 lb = kg 	Imperial vehicle weight in Asphalt Streetstorm. Asphalt 3, 2 and 1 use instead.
Pound-foot 	lbf⋅ft	Imperial	Torque 	1 lbf⋅ft = N⋅m 	Unused, would be the imperial equivalent to for torque in Asphalt Streetstorm.
Pound-force 	lbf 	Imperial	Force 	1 lbf = 4.448 N 	Unused, would be part of for imperial torque in Asphalt Streetstorm.
Second 	s 	Both 	Time 	(Base) 	Acceleration times for 0–100 km/h and 0–60 mph in most Asphalt games, brake time 100–0 in Asphalt 3 as well as timers in most Asphalt games.
Watt 	W 	Metric 	Power 	(Base) 	Unused, would be part of for metric engine power in Asphalt Streetstorm, 4, 3 and 2.
Yard 	yd 	Imperial	Length 	1 yd = 3 ft1 yd = 0.9144 m 	Imperial unit for distances in most Asphalt games.
== References ==
Category:Measurement