9 categories (length, mass, temp, volume, speed, area, pressure, energy, time), shows both result and conversion factor

# Unit Converter - NumWorks
# Created by Alvar Laigna - https://alvarlaigna.com
# Arrows:select OK:choose Back:back
from kandinsky import fill_rect as F, draw_string as D
from ion import keydown as K
from time import sleep as Z
SW,SH=320,222
BK=(0,)*3;WH=(255,)*3
BL=(50,110,230);TL=(0,190,190)
YL=(220,200,60);GN=(60,190,60)
DG=(120,)*3
okv=1 if K(4)or K(52) else 0
def okd(): return K(4)or K(52)
def okp():
 global okv
 d=okd()
 if d and not okv:
  okv=1
  return True
 if not d:okv=0
 return False
def wup():
 while okd():Z(0.02)
 Z(0.12)
def menu(title,items,sub=False):
 sel=0;n=len(items)
 while True:
  F(0,0,SW,SH,BK)
  D(title,SW//2-len(title)*5,6,TL,BK)
  F(0,24,SW,2,(40,)*3)
  for i in range(n):
   y=34+i*22
   if i==sel:
    F(8,y,SW-16,20,BL)
    D("> "+items[i],14,y+2,WH,BL)
   else:
    D("  "+items[i],14,y+2,DG,BK)
  if sub:D("Back=return",100,SH-16,(60,)*3,BK)
  else:D("Back=quit",115,SH-16,(60,)*3,BK)
  while True:
   if K(1):sel=(sel-1)%n;Z(0.15);break
   if K(2):sel=(sel+1)%n;Z(0.15);break
   if okp():wup();return sel
   if K(17):return-1
   Z(0.04)
def inp(prompt):
 try:return float(input(prompt))
 except:return None
def show(lines):
 F(0,0,SW,SH,BK)
 D("RESULT",130,6,TL,BK)
 F(0,24,SW,2,(40,)*3)
 for i,ln in enumerate(lines):
  c=YL if i==len(lines)-1 else WH
  D(str(ln),14,34+i*20,c,BK)
 D("OK=back",130,SH-16,DG,BK)
 while True:
  if okp()or K(17):wup();return
  Z(0.04)
# Categories: (name, [(unit_name, factor_to_base)])
# Length base=m
LEN=("Length",[
 ("mm",0.001),("cm",0.01),("m",1.0),
 ("km",1000.0),("in",0.0254),("ft",0.3048),
 ("yd",0.9144),("mi",1609.344)])
# Mass base=kg
MAS=("Mass",[
 ("mg",0.000001),("g",0.001),("kg",1.0),
 ("oz",0.028349523125),("lb",0.45359237)])
# Volume base=L
VOL=("Volume",[
 ("mL",0.001),("L",1.0),("gal(US)",3.785411784),
 ("fl oz",0.0295735296),("cup",0.2365882368)])
# Speed base=m/s
SPD=("Speed",[
 ("m/s",1.0),("km/h",0.27777778),
 ("mph",0.44704),("knots",0.51444444)])
# Area base=m2
ARE=("Area",[
 ("mm2",0.000001),("cm2",0.0001),("m2",1.0),
 ("km2",1000000.0),("in2",0.00064516),
 ("ft2",0.09290304),("acre",4046.8564224)])
# Pressure base=Pa
PRS=("Pressure",[
 ("Pa",1.0),("kPa",1000.0),("atm",101325.0),
 ("bar",100000.0),("psi",6894.757293168),
 ("mmHg",133.322387415)])
# Energy base=J
ENR=("Energy",[
 ("J",1.0),("kJ",1000.0),("cal",4.184),
 ("kcal",4184.0),("Wh",3600.0),
 ("kWh",3600000.0),("eV",1.602176634e-19)])
# Time base=s
TIM=("Time",[
 ("s",1.0),("min",60.0),("h",3600.0),
 ("day",86400.0),("week",604800.0),
 ("year",31557600.0)])
CATS=[LEN,MAS,VOL,SPD,ARE,PRS,ENR,TIM]
TEMP_NAMES=["C","F","K"]
def fmt(v):
 if abs(v)<0.0001 and v!=0:
  return "%.6e" % v
 if abs(v)>=1000000:
  return "%.6e" % v
 if v==int(v) and abs(v)<1e15:
  return str(int(v))
 s="%.6f" % v
 s=s.rstrip("0").rstrip(".")
 return s
def to_c(v,u):
 if u==0:return v
 if u==1:return (v-32)*5.0/9.0
 return v-273.15
def from_c(v,u):
 if u==0:return v
 if u==1:return v*9.0/5.0+32
 return v+273.15
def conv_temp(fi,ti,val):
 c=to_c(val,fi)
 return from_c(c,ti)
def do_temp():
 while True:
  fi=menu("Temp: From?",TEMP_NAMES,True)
  if fi<0:return
  ti=menu("Temp: To?",TEMP_NAMES,True)
  if ti<0:continue
  while True:
   v=inp("Value in "+TEMP_NAMES[fi]+": ")
   if v is None:break
   r=conv_temp(fi,ti,v)
   r1=conv_temp(fi,ti,1.0)
   fn=TEMP_NAMES[fi];tn=TEMP_NAMES[ti]
   lines=[
    "Temperature",
    "",
    fmt(v)+" "+fn+" = "+fmt(r)+" "+tn,
    "",
    "1 "+fn+" = "+fmt(r1)+" "+tn
   ]
   show(lines)
def do_cat(cat):
 name,units=cat
 unames=[u[0] for u in units]
 while True:
  fi=menu(name+": From?",unames,True)
  if fi<0:return
  ti=menu(name+": To?",unames,True)
  if ti<0:continue
  while True:
   fn=units[fi][0];tn=units[ti][0]
   v=inp("Value in "+fn+": ")
   if v is None:break
   ff=units[fi][1];tf=units[ti][1]
   r=v*ff/tf
   r1=ff/tf
   lines=[
    name,
    "",
    fmt(v)+" "+fn+" = "+fmt(r)+" "+tn,
    "",
    "1 "+fn+" = "+fmt(r1)+" "+tn
   ]
   show(lines)
def run():
 cats=["Length","Mass","Temperature",
  "Volume","Speed","Area",
  "Pressure","Energy","Time"]
 while True:
  s=menu("Unit Converter",cats)
  if s<0:return
  if s==2:
   do_temp()
  else:
   idx=s if s<2 else s-1
   do_cat(CATS[idx])
run()