Understanding script page eighths
Why pages are measured in eighths, how to add them without drift, and the one mistake spreadsheets make every time.
Checked against sources
A script page is divided into eight parts. A scene that fills a third of a page is 3/8; one that runs a page and a half is 1 4/8. The convention exists because eighths are easy to eyeball against a marked-up page, and because they add up without anybody reaching for a calculator.
Eighths are not an approximation of a decimal. They are the unit. A scene is 3/8 of a page, not 0.375 of a page that happens to round nicely.
Why they are not written as decimals
Because decimals drift. Eighths convert to numbers a computer cannot hold exactly, and adding them repeatedly accumulates error.
What a spreadsheet does
0.375 + 0.375 + 0.25
= 1.0000000000000002
Three scenes that plainly total one page. The spreadsheet disagrees, quietly, in the sixteenth decimal place. Add forty scenes and the error is large enough to change a rounded total.
This calculator never holds a decimal. Every value is stored as a whole number of eighths — 3/8 is the integer 3 — and the decimal only appears at the end, for display. The same three scenes come to exactly 1, because 3 + 3 + 2 = 8.
Reading and writing them
A page count has two parts: whole pages, then eighths. Both are written together, largest first.
The same amount, four ways
2 3/8 pages
19/8
2.375
2 pages and 3 eighths
The fraction is always less than a whole page. You would not write 1 9/8; that is 2 1/8. And a scene shorter than a page has no whole part at all — just 5/8.
Where the mistakes happen
Mixing units mid-list. Adding 2 3/8 to 1.5 to 7/8 by hand invites an error. The calculator accepts all three forms and converts them itself, so you can type whatever the paperwork gave you.
Halves and quarters. People write 1/2 when they mean 4/8. That is accepted — halves and quarters divide into eighths cleanly. Thirds do not, so 1/3 is rejected rather than rounded to something that looks close.
Decimals that are not eighths. 2.3 is not a page count. It sits between 2 2/8 and 2 3/8, and the calculator says so rather than picking one.
Nothing here is rounded, at any stage. If a total comes out at 12 4/8, that is what was entered — the tool has not nudged it to 12 1/2 or to 12.5 behind your back.
Subtracting
Days get cut. The calculator subtracts as well as adds, and if the total goes below zero it says so rather than showing a tidy-looking answer — a negative page count almost always means a line was marked subtract when it should have been add.