Blockpad supports units, and assigning a unit to a number is as easy as typing the unit after it. Blockpad has a set list of built-in units, all of which are listed below.
To assign a unit to a number, type the unit text after it. For example,
57 kg, or
The unit text must match the built-in unit stored in the Blockpad library, but Blockpad will often auto correct to what's intended. The dropdown selection will also help.
Composite units can be formed using built-in units and regular operators (*, /, and ^). For example,
12 kg*m/s^2, or
To convert a value to a different unit, the to key word is used. In a formula, type in "to desired unit" after the value you wish to convert. For example,
12 kg*m/s^2 to lbf,
20 F to C, or
25000 lbf to kN.
The compatible function checks if two numbers have compatible units. In a sense, it checks if two numbers with units can be added together or if the units of one number could be converted to the units of the other. You can also think of it as checking if the fundamental dimensions are the same (length, mass/length^3, etc).
If you need to strip units from a number for a calculation, it is best practice to divide that number by the units you want the number to represent.
For example, the effective seating width of a gasket is calculated with this equation
0.5*sqrt(b_0), where b_0 is in inches and the result is in inches as well. In Blockpad, the result of this formula as-is will have units of in^0.5.
To correct for this, the Blockpad formula should be
0.5*sqrt(b_0/(1 in))*(1 in). This way, any length unit can be used for b_0, and that unit will be converted to inches and cancelled. Then the result is multiplied by 1 inch so that the result is in inches.
In Blockpad, some units take a multi-level form using multiple units that are successively smaller. Ft-in units are the primary example of this.
4 ft 5 in + 10 in,
(4 ft 5 in)*(3 ft 8 in), and
(12 ft 7.5 in)/3 are all legitimate formulas in Blockpad.
Time units are another example of this, including day-hr-min, hr-min, and min-sec, which are useful for date calculations.
To convert to this kind of unit, type the units with a space between them after the "to" keyword. For example,
10 m to ft in,
2.2 day to day hr min, or
2.7 hr to hr min.
Because conventional temperature scales have different starting points (0 C ≠ 0 F), converting between temperatures and converting between temperature differences require different approaches. So in Blockpad, differences in temperature have units of ΔF or ΔC.
Because psia and psig have a similar problem (0 psia ≠ 0 psig), differences in psig are represented with Δpsig units. Note this only applies when psig is explicitly used. Regular psi is a unit and is the typical US customary unit for force/length^2.
There is a challenge with converting rpm (revolutions per minute), because it can be considered a unit of frequency (like Hz) or of angular velocity (deg/min or rad/min). This is further complicated by radians, because numbers with radians as a unit can also be considered unitless.
Blockpad handles this problem using context dependent conversions. So converting from rpm, "1 rpm to rad/min" = 2*pi rad/min (angular velocity) and "1 rpm to min^-1" = 1 min^-1 (frequency).
Converting from rad/min, "2*pi rad/min to rpm" = 1 rpm (angular velocity) and "2*pi rad/min to min^-1" = 2*pi min^-1 (frequency).
Note that this means the original value will be lost if converted between different interpretations. In the example below, x is in rpm; y equals x converted to rad/min; and z equals y converted to min^-1. x ≠ z, even though if you wrote out the equations they would be x = y = z.
The simple pounds unit (lb) is flexible with conversions to mass or force units.
1 lb to kg gives 0.454 kg as the result, and
1 lb to N returns 4.448 N.
Pounds force (lbf) and pounds mass (lbm) are not flexible. Pounds force is only compatible with force units and pounds mass is only compatible with mass units.
1 lbf to kg will give an error.
Putting a $ sign in front of a number and putting "usd" behind a number do the same thing. So,
|lb||pound (general use)|
|oz||ounce (1/16 lb)|
|kip||kip (1000 lbf)|
|psi||pound per square inch (lbf/in^2)|
|ksi||kip per square inch (kip/in^2)|
|ft in||foot-inch (see section above)|
|pcf||pound per cubic foot (lbf/ft^3)|
|kcf||kip per cubic foot (kip/ft^3)|
|psf||pound per square foot (lbf/ft^2)|
|ksf||kip per square foot (kip/ft^2)|
|plf||pound per linear foot (lbf/ft)|
|klf||kip per linear foot (kip/ft)|
|sy||square yard (yd^2)|
|cy||cubic yard (yd^3)|
|cfs||cubic foot per second (ft^3/s)|
|psia||absolute pound per square inch (pressure)|
|psig||gauge pound per square inch (pressure)|
|Δpsig||difference gauge pound per square inch|
|sf||square foot (ft^2)|
|cf||cubic foot (ft^3)|
|nautical mile||nautical mile|
|mph||mile per hour|
|ton||US customary ton (2000 lbf)|
|gal||US gallon (231 in^3)|
|gpm||US gallon per minute|
|Btu||British thermal unit (thermochemical definition, 1054.3503 J)|
|slug||slug mass unit (1 lbf*s^2/ft)|
|hp||mechanical horsepower (550 ft*lbf/s)|
|quart||quart (1/4 gal)|
|pint||pint (1/2 quart)|
|cup||cup (1/4 quart)|
|fl oz||fluid ounce (1/8 cup)|
|fl oz FDA||FDA fluid ounce (30 mL)|
|Tbsp||tablespoon (1/2 fl oz)|
|tsp||teaspoon (1/6 fl oz)|
|bar||bar (100,000 Pa)|
|mm Hg||millimeters mercury (pressure)|
|cc||cubic centimeter (cm^3)|
|g0||gravity/ "g's" (1 g0 = 9.807 m/s^2)|
|gravity||gravity/ "g's" (1 gravity = 9.807 m/s^2)|
|coulomb||Coulomb (electric charge)|
|ohm||Ohm (same as Ω)|
|cal||"small" calorie (4.184 J)|
|kcal||"large" calorie (1000 cal or 4184 J)|
|ppm||parts per million|
|ppb||parts per billion|
|day hr min sec||day-hour-minute-second|
|day hr min||day-hour-minute|
|hr min sec||hour-minute-second|
|rpm||rotation per minute|
|deg min sec||degree-minute-second|
|rev||One revolution (rpm*min)|
|px||virtual pixel (1/96 inch)|
|pt||point (1/72 inch)|
Note that terms i and j for complex number are inputed like units, as shown, but they define an imaginary number, rather than a literal number with a unit.
|i||the imaginary unit|
|j||the imaginary unit (same as i)|
Note that conversion between currencies is not supported right now.
|usd||United States Dollar|
|nzd||New Zealand Dollar|