DuckieDai Physics Unit Converter Python Program

physics · MIT License

Overview

Convert physics units both ways across 10 categories, from length, speed, and temperature to force, energy, and pressure, with the work and the conversion factor shown.

Owner-tested on a TI calculator
Most requested
Version 1.0.0
2590 bytes
No imports

Download PHYSUNIT.py Read the source How to install

Before you run it

TI-84 Plus CE Python · No calculator OS or Python App version has been verified.
TI Connect CE .py transfer to the Python App; the owner's transfer details were not recorded
Each conversion uses the exact or standard factor shown on the result screen, such as 1 in = 2.54 cm or 1 cal = 4.184 J.
Temperatures are converted with the Celsius, Fahrenheit, and kelvin formulas, not a single factor.
A value may be a decimal or a fraction a/b; the bottom of a fraction cannot be 0.

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Learn the math

How to convert units in physics

The idea

A measurement is a number and a unit together. Converting changes the unit, so the number has to change the other way: a meter is 100 centimeters, so 3 m is 300 cm. The amount itself stays the same.

Most physics formulas expect SI units: meters, kilograms, seconds, m/s, kelvin, newtons, joules, and pascals. Converting a given value into SI before using a formula is one of the most common steps in a physics problem, and a skipped conversion is one of the most common lost points.

The formula

going to the second unit: value * factor

going back to the first unit: value / factor

C to F: x*9/5+32, F to C: (x-32)*5/9, C to K: x+273.15

factor: how many of the second unit make one of the first, such as 1 mph = 0.44704 m/s
x: the value you typed
SI units: the base units most physics formulas are written for

Using the program

Pick a category from 1 Length to 10 Pressure, then a pair of units.
Choose 1 to convert from the first unit to the second, or 2 for the other way.
Type the value. A fraction such as 3/4 works too.
The program shows the answer, the work as x * factor or x / factor, and the factor itself. A blank entry goes back one screen.

Worked example

A car drives at 60 mph. What is that in m/s? Choose 4 Speed, then 1 mph / m/s, then 1 for mph to m/s, and type 60.

60 * 0.44704 = 26.8224

The program shows 26.8224 m/s with Work: x * 0.44704.

A fever thermometer reads 98.6 F. Choose 5 Temp, then 1 C / F, then 2 for F to C, and type 98.6. The program shows 37 C with Work: (x-32)*5/9.

Room temperature, 25 C, is 298.15 K: choose 5 Temp, then 2 C / K, then 1, and type 25.

Tips and common mistakes

Check the direction before you trust the answer: a smaller unit always needs a bigger number, so 2 km is 2000 m, not 0.002 m.
Area and volume units are squared and cubed, so the factors are too: 1 m2 is 10,000 cm2, not 100 cm2.
Temperatures do not scale by one factor. 0 C is 32 F, not 0 F, so use the formula, and never go below absolute zero, 0 K.
Round only the final answer, using your class's significant figure rules; the program shows up to 6 significant digits.

Where this comes up

Unit conversion is the first skill in nearly every physics and chemistry course, and it comes back in every unit, from kinematics and forces to energy, gases, and pressure.

Exact reviewed bytes

Source code

Download .py

View source below, copy it when JavaScript is available, or download the exact .py bytes.

N=("Length","Mass","Time","Speed","Temp","Area","Volume","Force","Energy","Pressure")
P=((("m","cm",100),("km","m",1000),("ft","m",.3048),("in","cm",2.54)),
(("kg","g",1000),("lb","kg",.45359237),("g","mg",1000)),
(("hr","s",3600),("min","s",60),("day","hr",24)),
(("mph","m/s",.44704),("km/h","m/s",1/3.6),("ft/s","m/s",.3048)),
(("C","F",0),("C","K",1),("F","K",2)),
(("m2","cm2",1e4),("km2","m2",1e6)),
(("L","m3",.001),("mL","L",.001),("cm3","m3",1e-6)),
(("lbf","N",4.4482216152605),("kgf","N",9.80665)),
(("kJ","J",1000),("cal","J",4.184),("kcal","J",4184),("kWh","J",3.6e6)),
(("atm","Pa",101325),("kPa","Pa",1000),("psi","Pa",6894.757293168)))
def clr():print("\n"*11)
def pg():input("[enter]");clr()
def fmt(x):
 if abs(x)<1e15 and abs(x-round(x))<1e-9:return str(int(round(x)))
 return "%.6g"%x
def pick(t,L):
 while 1:
  clr();print(t)
  for i in range(0,len(L),2):print("  ".join(str(j+1)+" "+L[j] for j in range(i,min(i+2,len(L)))))
  s=input("Choice (blank=back)? ").strip()
  if not s:return -1
  try:
   n=int(s)-1
   if 0<=n<len(L):return n
  except ValueError:pass
def num(p):
 while 1:
  s=input(p).strip()
  if not s:return None
  try:
   if "/" in s:a,b=s.split("/");return float(a)/float(b)
   return float(s)
  except (ValueError,ZeroDivisionError):print("Number or a/b")
def tmp(k,f,x):
 if k==0:return (x*9/5+32,"x*9/5+32",x+273.15) if f else ((x-32)*5/9,"(x-32)*5/9",(x-32)*5/9+273.15)
 if k==1:return (x+273.15,"x+273.15",x+273.15) if f else (x-273.15,"x-273.15",x)
 a=(x-32)*5/9+273.15
 return (a,"(x-32)*5/9+273.15",a) if f else ((x-273.15)*9/5+32,"(x-273.15)*9/5+32",x)
def run(g,i):
 l,r,c=P[g][i]
 while 1:
  clr();print("1 "+l+" -> "+r+"\n2 "+r+" -> "+l)
  w=input("Direction (blank=back)? ").strip()
  if not w:return
  if w not in("1","2"):continue
  f=w=="1";a,b=(l,r) if f else (r,l)
  v=num("Value in "+a+"? ")
  if v is None:continue
  if g==4:
   y,h,k=tmp(i,f,v)
   if k<-1e-9:clr();print("Below absolute zero!");pg();continue
  else:y=v*c if f else v/c;h=("x * " if f else "x / ")+fmt(c)
  clr();print("DuckieDai RESULT\n"+fmt(v)+" "+a+" =\n"+fmt(y)+" "+b+"\nWork: "+h)
  if g!=4:print("(1 "+l+" = "+fmt(c)+" "+r+")")
  print("Round per class rules");pg()
def main():
 clr();print("PHYS UNIT CONVERTER\n      __\n  ___(o )>  quack!\n  \\ <_. )\n   `---'\nDuckieDai (TM)\nhiddenwordscanner.com\nBlank entry = back");pg()
 while 1:
  g=pick("PHYSUNIT - DuckieDai",N)
  if g<0:break
  L=[l+" / "+r for l,r,c in P[g]]
  while 1:
   i=pick(N[g],L)
   if i<0:break
   run(g,i)
 clr();print("Quack! Goodbye\nDuckieDai (TM)\nhiddenwordscanner.com")
main()

N=("Length","Mass","Time","Speed","Temp","Area","Volume","Force","Energy","Pressure")
P=((("m","cm",100),("km","m",1000),("ft","m",.3048),("in","cm",2.54)),
(("kg","g",1000),("lb","kg",.45359237),("g","mg",1000)),
(("hr","s",3600),("min","s",60),("day","hr",24)),
(("mph","m/s",.44704),("km/h","m/s",1/3.6),("ft/s","m/s",.3048)),
(("C","F",0),("C","K",1),("F","K",2)),
(("m2","cm2",1e4),("km2","m2",1e6)),
(("L","m3",.001),("mL","L",.001),("cm3","m3",1e-6)),
(("lbf","N",4.4482216152605),("kgf","N",9.80665)),
(("kJ","J",1000),("cal","J",4.184),("kcal","J",4184),("kWh","J",3.6e6)),
(("atm","Pa",101325),("kPa","Pa",1000),("psi","Pa",6894.757293168)))
def clr():print("\n"*11)
def pg():input("[enter]");clr()
def fmt(x):
if abs(x)<1e15 and abs(x-round(x))<1e-9:return str(int(round(x)))
return "%.6g"%x
def pick(t,L):
while 1:
clr();print(t)
for i in range(0,len(L),2):print(" ".join(str(j+1)+" "+L[j] for j in range(i,min(i+2,len(L)))))
s=input("Choice (blank=back)? ").strip()
if not s:return -1
try:
n=int(s)-1
if 0<=n<len(L):return n
except ValueError:pass
def num(p):
while 1:
s=input(p).strip()
if not s:return None
try:
if "/" in s:a,b=s.split("/");return float(a)/float(b)
return float(s)
except (ValueError,ZeroDivisionError):print("Number or a/b")
def tmp(k,f,x):
if k==0:return (x*9/5+32,"x*9/5+32",x+273.15) if f else ((x-32)*5/9,"(x-32)*5/9",(x-32)*5/9+273.15)
if k==1:return (x+273.15,"x+273.15",x+273.15) if f else (x-273.15,"x-273.15",x)
a=(x-32)*5/9+273.15
return (a,"(x-32)*5/9+273.15",a) if f else ((x-273.15)*9/5+32,"(x-273.15)*9/5+32",x)
def run(g,i):
l,r,c=P[g][i]
while 1:
clr();print("1 "+l+" -> "+r+"\n2 "+r+" -> "+l)
w=input("Direction (blank=back)? ").strip()
if not w:return
if w not in("1","2"):continue
f=w=="1";a,b=(l,r) if f else (r,l)
v=num("Value in "+a+"? ")
if v is None:continue
if g==4:
y,h,k=tmp(i,f,v)
if k<-1e-9:clr();print("Below absolute zero!");pg();continue
else:y=v*c if f else v/c;h=("x * " if f else "x / ")+fmt(c)
clr();print("DuckieDai RESULT\n"+fmt(v)+" "+a+" =\n"+fmt(y)+" "+b+"\nWork: "+h)
if g!=4:print("(1 "+l+" = "+fmt(c)+" "+r+")")
print("Round per class rules");pg()
def main():
clr();print("PHYS UNIT CONVERTER\n __\n ___(o )> quack!\n \\ <_. )\n `---'\nDuckieDai (TM)\nhiddenwordscanner.com\nBlank entry = back");pg()
while 1:
g=pick("PHYSUNIT - DuckieDai",N)
if g<0:break
L=[l+" / "+r for l,r,c in P[g]]
while 1:
i=pick(N[g],L)
if i<0:break
run(g,i)
clr();print("Quack! Goodbye\nDuckieDai (TM)\nhiddenwordscanner.com")
main()

Filename: PHYSUNIT.py
Size: 2590 bytes
SHA-256: 6eadd5329608e01f94609385aed38913d224332e157ccc007f0f60953c5dfe24

Usage

Inputs

A category: Length, Mass, Time, Speed, Temp, Area, Volume, Force, Energy, or Pressure
A pair of units and a direction, such as 1 for mph to m/s or 2 for m/s to mph
The value to convert; a blank entry goes back

Outputs

The converted value with its unit, the work as x * factor or x / factor, and the conversion factor
For temperature, the formula used, such as (x-32)*5/9

Units: Metric and US customary units in 10 categories, including m/s, kelvin, newtons, joules, and pascals.

Assumptions and limitations

Assumptions

Each conversion uses the exact or standard factor shown on the result screen, such as 1 in = 2.54 cm or 1 cal = 4.184 J.
Temperatures are converted with the Celsius, Fahrenheit, and kelvin formulas, not a single factor.

Constraints

A value may be a decimal or a fraction a/b; the bottom of a fraction cannot be 0.
A temperature below absolute zero is refused.

Known failures

Answers that are not whole numbers show 6 significant digits, so round them as your class asks.
Only the 30 unit pairs on the menus are included; chain two conversions for others, such as mi to m through km.
inf and nan are accepted as values and shown as inf or nan.

Compatibility and review

Review status: Owner-tested on a TI calculator
Tested on: Owner reports personally running this program on a TI-84 Plus CE Python calculator; the test date, OS version, and Python App version were not recorded
What happened: Owner reported pass on the calculator for this exact file. It is published unchanged.
Dependencies: No imports
Suggested calculator name: PHYSUNIT — you can give it another valid, unique name when you transfer it
Desktop test cases: Not available for this interactive-only source

This exact source auto-launches an interactive calculator session, so compatibility evidence comes from the recorded physical-device review rather than an importable desktop fixture.

Transfer and launch

Download the .py file, send it to your calculator with TI Connect CE as PHYSUNIT or another name, then open the Python App and try the worked example on this page first. This release has no verified calculator OS or Python App version; treat transfer and execution as unverified until independently tested.

Full installation and troubleshooting guide. Check your teacher's or exam's rules before using any program.

Version history

1.0.0 — current version, published 2026-10-27. Download this reviewed version

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