Here's a simple one so you can get used to how this works. You enter a value on the left and click the "Convert To" button.

Inches: Feet: Inches:

If you entered 63, it should show 5 feet and 3 inches.

The calculators are specifically designed for builders using ordinary measuring tapes. All measurements are based on 1/16th of an inch.

Fraction: / Decimal:

When you enter a fraction there is always a field to type a number (filled in as "7" above, the numerator, or top number) and a popup with choices 2, 4, 8, and 16 (the denominator or bottom number). 16 is always selected as the default. If you enter 7/16, it should convert to 0.4375.

You can enter fractions like 1/2 by entering 1 in the field and selecting 2 from the popup, or you can enter it as 8/16. Both ways work fine.

It's also okay to enter improper fractions into any fraction box. You can enter 24/16 in the box above and it will convert to 1.5.

These calculators always approximate to useful measurements for a tape measure.

Decimal: Fraction: /

If you use the example of .333 above it will convert to 5/16, which is the closest approximation on the 16ths scale (5/16 = 0.3125).

You will use the foot/inch/fraction method of entering values all the time. It looks like this:

' and / " Inches:

You enter feet into the first box, inches into the second, and the the numerator and denominator, like you did before. In this example, it's preset to 2 feet, 1 3/4", which should convert to 25.75.

You don't actually have to enter feet and inches. You can enter 0' and any number of inches into any of these boxes.

' and / " Inches:

In this example 32 1/8" will convert to 32.125.

You don't even need to use the fraction. You can enter decimal numbers for feet and inches.

' and / " Inches:

For this calculator this isn't very useful but in some of the more complicated calculators it can come in handy. If you enter a non-integer into the inches field the numerator and denominator fields will be ignored. Also this only works for feet and inches. The numerator must be an integer.

And there's the reverse version:

Inches: ' / "

128.125" is 10'-8 1/8"

Here's where we get to the fun stuff. This looks really complicated, but it's not that bad.

Add: ' and / " + ' and / " ' / "

In this example, you'd adding 1'-3 1/2" and 7 9/16". Hit the = button and it should display 1'-11 1/16"!

And remember, you can skip the feet, enter decimals in the feet and inch fields, and improper fractions are okay.

The multiplication and division calculators should be fairly obvious by now:

Divide: ' and / " ÷ ' / "

In this example dividing 36 3/4" by 3 results in 1'-0 1/4" (12 1/4"). The factor you multiply or divide by can be a decimal number, too.

Angle calculator. This is the most complicated one, but it's very powerful.

A=adjacent, B=opposite, C=hypotenuse

A: ' and / " ("run")

B: ' and / " ("rise")

C: ' and / " ("hypotenuse")

Angle: °

The idea is that you enter two pieces of information that you know and it will figure out the other two.

Say you have a 4/12 pitch roof. Enter A=12" and B=4" and kit the Calculate button. It should come back with C=1'-0 5/8" which is the distance across the surface of your roof. And the angle is 18.43°.

Make sure you hit the Clear button before reusing the calculator.

If you enter A=3' and B=4' it should come back with C=5' and Angle=53.13°.

Say I have a slope. I've measured that I have a 96" run and a 78" rise. What's the angle?

adjacent=96, opposite=78

A: ' and / " ("run")

B: ' and / " ("rise")

C: ' and / " ("hypotenuse")

Angle: °


Furthermore, I have a piece that I want to intersect it. It's a 2x6 (1 1/2" x 5 1/2"). How far from the edge do I have to measure back to make my cut?

2x6 intersecting 39° slope

A: ' and / " ("run")

B: ' and / " ("rise")

C: ' and / " ("hypotenuse")

Angle: °

I have to cut off 6 13/16".

Ready? Go to the real calculator now.

Copyright 2010 Rick Kaseguma. All rights reserved.