3.0 User's Manual
BoardCalc 3.0 is an Android® OS
application, a general-purpose calculator useful for working
with wood. BoardCalc ‘thinks’ in fractions, feet and
inches, yards, board feet, or metric. It does conversions
between metric and imperial units, decimal and fractions, board
feet and areas/volumes. BoardCalc makes it a little more
comfortable to subtract 5 5/8” from 1’ 3 3/32” or add 5mm to
The strength of this calculator is that it works in fractions or
decimal with equal ease, works with dimensions in inches, feet,
yards, cm, mm meters, or board feet, converts between units of
measure or fraction / decimal, can round bizarre fractions to
more sensible values, and calculates board feet from two
dimensions, three dimensions, surface area or volume.
More info is available on the web at: www.boardcalc.com
- Supports Android OS 2.1 (Eclaire) or newer
- Work in any combination of fractions and decimal, convert
back and forth with a button press
- Round any fraction to the nearest half, quarter, eighth,
sixteenth, thirty-second or sixty-fourth
- Work in and convert between inches, feet, yards,
millimeters, centimeters, and meters in length, area or volume
- Calculate board feet from 2 or 3 dimensions, an area, or a
- Enter values as whole / fraction, decimal, or feet / inches
- Ten memory registers, any of which can be locked to keep the
value from being accidentally replaced
- Backspace button: a goof doesn't mean starting over
- Percent button; add or subtract a percentage of any value.
Multiply or divide by a percentage.
- History to show recent calculations
- Input and calculations
- Calculating Board Feet
- Memory registers
- Things to know
- Preferences (settings)
- Trial period
1) Input and
Like most of the
calculators you have used to do simple math, this is an algebraic
input calculator (as opposed to RPN, Reverse Polish Notation). You
enter the first value, then the math operation (such as '+'), the
second value, and then '='. Each value in the calculation can be a
plain number, length, area or volume. The only requirement is that
the operation and the values given be possible: dividing a length
by an area, for example, can't be done. If one value in an
addition or subtraction has units and the other does not, both are
assumed to have the same units: 5 + 5cm = 10cm. For multiplication
or division, what you see is what you get, in order to correctly
keep track of whether the result is an area, length or volume. 5 x
5cm is 25cm, while 5cm x 5cm is 25 sq cm.
Many are the ways to enter values in BoardCalc:
- Fractions 3/4
- Decimal -
- Metric - 3.4mm
.75cm 3 3/4m
- Inches/feet - 3.4" .75'
3' 3 3/4"
- Area - 2 sq
ft 3 1/2 sq
m 45.7 sq in
- Volume - 2 cu ft 3
1/2 cu m 45.7 cu in
Fractions use the (sp) (space) and
/ (fraction) buttons. For example, to enter two and a half, the
buttons 2 (sp) 1 /
2 are pressed.
Dimensions can be entered in
feet/inches/fraction. If a value includes two whole numbers, it
isn't necessary to include the units - the calculator knows
that 2 (sp) 2
can only be feet and inches. A fraction on the end of two whole
numbers works the same way (no units required). The following are
all legal, and all represent the same value:
2' 2 1/2"
2 2 1/2"
2 2 1/2
2' 2 1/2 26 1/2"
Units: m = meters, cm =
centimeters, mm = millimeters, yd = yards, ft = feet, and In =
inches. If the screen is set to Small in Screen Size, only three
of these will be visible at a time, below a button marked "i/m".
This stands for "imperial/metric" (or inches/meters if you
prefer). Pressing this button will swap the three buttons below it
to m/cm/mm or yd/ft/In.
Multiple dimensions can be entered for a single calculation using
the 'by' button. This can be useful to calculate area, volume or
3" by 8' BdFt
2.00 bd ft
3" by 8'
by 2 BdFt ] gives 4.00 bd ft
1 by 2 by
1 by 2 by
0.04 bd ft
1' by 2"
by 3cm = gives
21 44/127 cu in
Converting a value to different
units of measure is just a matter of entering the number, the
original units, and the new units. If you already have a result of
a calculation that has units, just press the new units. To convert
from fraction to decimal or vice versa, either press the /
(fraction) button, or press the same units again (pressing the
'in' button will flip between decimal inches and fractional
inches, for example):
5 cm in
1.97" (converted 5 cm to inches)
gives 1 123/127" (converted
decimal inches to fractional inches)
11' 7 3/4"
11.65' (converted feet/inches/fraction
to decimal feet)
gives 139.75" (converted
decimal feet to decimal inches)
An area in any units can also be
converted to BdFt, even though BdFt is a volume. The third
dimension is assumed to be 1" (4/4).
Calculating Board Feet
A board foot is a measure of volume.
If only two dimensions are entered, the third is assumed to be 4/4
when the BdFt button is pressed, since this is the most commonly
used lumber.. A surface area is converted to board feet the same
way, by assuming a thickness of 4/4. Either the by button or the x
(multiply) button can be used between values when calculating
board feet. Any number entered without units is assumed to be
12" by 8' BdFt
gives 8.00 bd ft
12 by 8'
by 1 BdFt gives 8.00 bd ft
12 x 8'
gives 8.00 bd ft
3cm by 1m
BdFt gives 0.32 bd ft
8" by 8'
by 1" = gives
768 cu in
gives 5.33 bd ft
gives 5 1/3 bd ft
A value like 1 123/127" is difficult
to find on a ruler. You can round this value to something more
sensible by touching
anywhere in the display area where the value lives, and scrolling
(moving) your finger left or right to change the rounding.
Scrolling left will round to smaller and smaller fractions until
64ths are reached. Moving right will round to larger fractions up
to 1/2. Scrolling all the way to the right will turn rounding off
so that the exact fraction is displayed. A fraction can be rounded
to the nearest 1/2, 1/4th, 1/8th, 1/16th, 1/32nd or 1/64th. This
selector only affects how the value is shown, the exact value is
always preserved. If the displayed value is rounded, a '~'
will show up in front of it to warn you, and the rounding value
(such as 1/64th) will show at the lower left side of the display.
There will be no '~' or rounding value if the value shown is
exact, even if rounding is turned on.
The original fraction is not
changed when it is rounded, only the display of the value is
affected. If rounding is turned off again, the exact original
value will be displayed again. All math will come out correctly,
regardless of rounding, but results can look odd. For example, if
you enter 3/16, and round to the nearest half, the result is ~0.
Now press MS, '+' and MR, the display will show ~0 + ~0.
The value 3/16 rounded to the nearest half is 0, which is shown
twice in the display. Now pressing '=' will add 3/16 to 3/16 to
In recent calculations, the last calculation shows ~0 + ~0 = ~1/2,
which is a nice trick if you can work it financially. Any time you
see the '~', remember that the value is rounded.
Note that rounding does not force
the fraction into the rounding chosen - fractions are always
reduced as far as possible. If 1/2 is rounded to the nearest
1/64th, it will still show up as 1/2 (not 32/64, and no '~'
is shown because the value is exact). And if 123/127 is rounded to
the nearest 1/64th, it will show ~31/32.
There are ten memory registers, of
which register 0 is special. The memory keys (MR, MS, M+, MC) in
the calculator use register 0. A normal press on MS saves the
current result to register 0. MR recalls the value from register 0
into the current calculation. M+ adds the current result to
whatever is already in register 0. MC clears register 0. When a
value is saved in memory register 0, an 'M' will show up in the
left side of the calculator display. If you only use these
keys and don't need to save any other values, you need never look
at the memory register page.
On the other hand, if you have calculations, measurements or
values that you would like to refer to later on, there are nine
more registers that you can use to save them. There are two ways
to put a value in them: a long press on MS will bring up the
memory register page. Pressing any of the ten lines will save the
current result in that register and flip back to the calculator
page. You can also fling across any screen or use the menu to
change to the memory page. A long press on any of the ten lines
will bring up a menu from which you can Save, Recall or Lock the
memory register. Save will put the current result in the memory
line (and stay on the memory page).
Recall works the same
way: a value can be recalled from any memory register by a long
press on the MR key and selecting a line, or by a long press on
any line in the memory page and selecting Recall. When you recall
a value from a memory register, BoardCalc will switch from the
memory register page to the calculator page whe
Lock is useful if there
are values in memory registers that you wish to protect from being
accidentally replaced. A long press on the line and selecting Lock
for the memory register will prevent any new value from being
stored there. A locked value can still be recalled, and can be
unlocked any time.
If a calculation is not yet
complete, pressing MS or M+ will
complete it and save/add the result to memory. For example,
+ 3 MS will show 5 in the calculator display and store 5
in memory register 0. The rounding and units of the calculator
value will be saved in the memory value. Again, the accuracy of
the value is not affected, only how it is displayed. But the same
number rounded to two different bases can be saved in two memory
registers, and will look different, even though they are exactly
the same value and will give exactly the same results in any
The memory keeps track of units just as the calculator does. If
you use M+ to add 5" to a value of 3 (no units) already in memory,
the memory result becomes 8". Any math operation that won't work
in the calculator will also fail for M+: trying to add a length to
a volume will beep and do nothing.
If the calculator beeps
when M+ is pressed, the operation is illegal and nothing was done.
This is probably because the values are a mix of length, volume or
area. Adding an area to a volume or length does not make sense. M+
with different units (mm/cm/m/in/ft) will always work as long as
both values are length, both are area or both are volume. A value
with no units can be added to anything. It will be given the units
of the other value.
Things to know
i) Chain calculations
You can do a chain of operations
without pressing the '=' button. Each time a new operation is
pressed, the previous operation is calculated and the result is
used as the first number for the new operation. For example, if
you press 1
+ 2 x 3 =, the result is 9. 1 + 2 becomes 3 when the 'x'
is pressed. Then 3 x 3 = 9.
ii) Board Feet and the NHLA method
BoardCalc figures board feet by
treating board feet as a volume: 144 cubic inches equals 1 board
foot. It does not make corrections for thickness less than an inch
or round thickness to the nearest 1/4. In fact, it does not do any
rounding at all in the calculations. The answer calculated is
therefore not necessarily what you would get using the NHLA method
to calculate board feet, especially for multiple boards where you
tally a surface measure first, rounding up one time and down the
next. It was done this way so that you can always see what you
get, with no hidden rounding to surprise you. If you need to use
the NHLA method to calculate board feet, it is up to you to do the
rounding. There are many discussions (and arguments) available
about this topic on the web and elsewhere.
iii) It beeps at me
Sometimes the machine is smarter
than we are. If BoardCalc beeps, it couldn't do what you asked it
to. This usually means that the dimension of the result is
impossible. Multiplying an area by an area, or adding a volume to
a length, for example, will get you a beep, because these don't
If converting units for an area or
volume, you don't need to press sq or cu, and you will be beeped
if you do. All that is required is inches, feet, etc. BoardCalc
already 'knows' that it is an area or volume.
iv) Overflow & Overrun
If numbers become too large
internally, they can cause an overflow, which means that BoardCalc
does not have enough room in a single number to hold the value or
complete a calculation. If this happens, OVERFLOW
is displayed. Too see this, enter 8888888888 (ten '8's) and press
Internal to the calculator, all
values are stored in inches. Because of this, it is possible for a
large value to be valid in inches, but too large to convert to cm
or mm. If this happens, the display will show Display Overrun.
The value is still valid, but can't be shown in these units. To
see this, enter 888888888" ( nine 8's and inches) and then convert
to cm (press cm).
BoardCalc stores all values as
fractions. This means that values entered as a fraction will
always be exact, as opposed to most calculators that store values
as a decimal mantissa with a power. 1/3 is really 1/3 in
BoardCalc, rather than .333333333.... with some vanishingly small
error. In practical terms, this just means that if rounding is not
turned on, the fraction displayed is the exact value and not an
The accuracy of a value does not change when you round it. The displayed value is all that
changes. This works the same way that decimal places do on this or
any other calculator. You can display any number of decimal places
you like, the value underneath is never affected. This can,
however, lead to some oddness in displayed values (see History
Decimal values and math are
accurate to about 8 significant digits. This is much less than
most scientific calculators, and was done to keep BoardCalc small
and agile. This level of accuracy would not be adequate if
calculating orbital parameters for a satellite shot to Jupiter.
But for an 8-foot board, an error of 1 in the 8th significant
digit amounts to .0244 microns. For comparison, a bacterium is
about 100 times larger (2 microns), and the thickness of a sheet
of paper is roughly 5000 times larger (100 microns). So .0244
microns should be accurate enough for most woodworking. To see
this, enter 200 cu m, and press m again to convert to a fraction.
The metric value is converted to inches internally, which
introduces an error that is cubed because this is a volume. The
total error ends up being 1/10709948.
vi) Recent Calculations History
Every time the general-purpose
calculator completes a calculation, it stores a line of text to
the recent calculations history. The text contains the parts of
the calculation and the result, as they appeared in the calculator
display. The entire calculation appears in the same line, as in:
11" by 11" by 11" = 1331 cu in
2 + 3 = 5
If enabled in preferences (default)
the list is saved when BoardCalc is exited. The list length is one
page at the smallest text size (12). The most recent calculation
is added below the other lines in the list. If the list is full,
all the other lines are bumped up one line and the top line is
thrown off. The list can be displayed in a number of text sizes,
which can be selected from a context menu (long press) or in
BoardCalc's settings. Changing the text size does not change the
length of the list, only how much of it is displayed right now.
After a few sessions, the recent
calculations list will fill up and stay full, putting new
calculations at the bottom. If you would like to see only what
you have done lately, the entire list can be deleted. Bring up
the context menu of the history page (long press) and press Clear History at the bottom
to delete the entire list.
Adding or subtracting a percentage
uses the units of measure of the other value. 20% + 10" is the
same as 10" + 20% (12"). Adding percentages might not do what
you expect. For addition or subtraction with two percentages,
the first number has units of measure which happen to be
percent, and the second value is used to do percentage math. If
you enter 60% + 50%, BoardCalc adds 50% of the first thing (60%)
back into it. 50% of 60% is 30%, so 60% + 50% = 90%.
For multiplication and division, percent values are simple, and
never act like they have units of measure. 50% is just another
way to say .50 or 1/2.
viii) Small screens, and the i/m button
On small devices, used in
landscape mode, there isn't enough room to fit all the buttons
into. You might notice that half the unit of measure buttons are
missing, and an extra button labeled i/m has appeared. This i/m
button swaps the units buttons between metric and imperial
units. Either mm, cm and m are showing, or in, ft and yd are
showing. Press i/m to switch to the other set.
ix) Fraction reduction
If a number is displayed as a
fraction, it is reduced as far as possible. It isn't very useful
to see a number like 8/16 in the display. There are, however,
limits. To reduce a fraction, it is divided by a series of prime
numbers. To keep calculation times reasonable, the primes only
go up through 127. So any number that has factors up through 127
will reduce properly but anything with larger factors will not
reduce completely. For example, if you enter 233/466, it will
not reduce to 1/2.
Preferences (settings) can only be
reached from the menu.
Sets the level of audible feedback
that sounds when a button is pressed. Choices range from none to
100% (full volume)
Sets the level of haptic (tactile)
feedback when a button is pressed. Choices: none, low,
medium, high. What each setting does may vary from one device to
another, and some devices may not support haptic feedback at
Determines whether the history list
will be preserved. Options are Save or Don't Save. If you choose
Don't Save, the history will disappear any time you leave
the program, bring up settings, view the help, or rotate your
device between portrait and landscape.
Controls the orientation of the
display. If Enabled,
rotating your device will also change the calculator
display. Selecting Portrait
will always take the long direction of the screen as
vertical, regardless of any orientation sensor. Landscape will always take
the long edge of the screen as horizontal.
Android devices come in a plethora
of shapes and sizes. On the smallest screens, the buttons in a
normal layout can become so small that it is difficult to press
the correct one, but there are acres of room to spare on a
tablet. Screen size of Auto will
use measurements from the device to pick the best fit. You can
force the display to Small
(intended for 3" screens), Normal
(longer aspect screens), Tab 5 or Tablet.
Small and Normal screens adjust to fill the screen, whatever
size it is. The Small layout has had a row's worth of buttons
removed: the remaining buttons will be larger (and easier to
press accurately on small screens). Any device smaller than a 5"
tablet will come up in Normal layout in Auto. If the buttons are
too small, you can force them to be larger by choosing Small
screen size in settings. For Tablet and Tab 5 settings,
the button sizes are fixed and the display puts all three pages
(memory, calculator and history) up at once. Note that if you
force the screen size to tablet on a small device, you may only
see the memory registers, and appear to be stuck on that screen;
since tablets show all three pages at once, switching between
pages is disabled.
f) Screen timeout
Your android device has a setting
for shutting off after being idle for a selected amount of time.
Screen: Timeout will
follow that setting and shut down. Screen: Keep on will ignore the setting and the
screen will stay on as long as BoardCalc is showing.
g) History text size
The list of recent calculations
can be shown in different sizes. Smaller fonts are harder to
read but show more on the page. Readability and size vary from
one device to another, so the choices range from 12 to 20.
The size selected has no affect on how much history is kept or
stored, it only affects how much is displayed. This text size
can also be set from the History page context menu (long press).
h) Help text size
The help text can be shown in
different sizes. Smaller fonts are harder to read but show more
on the page. Choices range from 12 to 20. This text size can
also be set from the Help page context menu (long press).
i) Number format
Set this to the format you usually
work in, either fraction or decimal. Any whole number you enter
(with no fraction or decimal point) will take this format. Any
math done with the number will then keep the default format. For
example, with the default of Fraction, entering 2 + 1/2 = will
yield 2 1/2. If the number format is changed to decimal,
entering 2 + 1/2 = will yield 2.5 in the display: the '2' is
taken as a decimal value, since it is ambiguous (not
specifically either a fraction or decimal value). The '1/2'
added to it does not change it's display format, it remains a
You can try this software out for
60 minutes after downloading. During the trial, everything
will be visible and fully functional. After the hour expires,
everything will still be visible, but no button presses will be
9) Requirements for BoardCalc 3.0
- Android OS 2.1 or above
- ~240K Bytes of memory for the application BoardCalc.apk
- Screen size of at least 2.8" diagonal