Use the policy that actually applies
Letter-grade and pass/fail thresholds vary between courses and institutions. The toolkit starts with percentage-only results and offers editable examples. An A–F scale with A beginning at 90% is an example, not a universal standard.
Locate the policy for the assessment you are marking, including any rounding or extra-credit rules. Give the custom scale a descriptive name that you will recognize later, without including student information.
Translate ranges into lower cutoffs
The builder stores the inclusive minimum for each band. If A begins at 90 and B begins at 80, then 90% is A and 89.999% is B under an unrounded classification policy. The top band has no further cutoff, which allows explicitly enabled extra credit.
Every non-percentage scale needs a lowest band beginning at zero. Cutoffs and grade labels must be unique. The ranges between adjacent lower bounds are implicit, so you do not have to type potentially inconsistent upper limits.
Check the boundaries, not just a typical score
Preview a score exactly at each cutoff and a score just below it. Then test whether the display rounds across that boundary. With an A cutoff of 90, 89.995 displays as 90.00 at two decimals but remains below A when classification uses the unrounded result.
If the course rounds before assigning letters, enable that policy explicitly. Display precision alone should not silently establish the grading rule.
Apply, duplicate and back up
Save and apply the scale to make it available across calculators in this browser. Duplicate a scale when you need a variation, so the original can still be selected. Saved workspaces retain a snapshot of their scale and grading policy.
Export the scale as JSON to transfer it manually to another device. Importing opens a copy for review; it does not publish anything or alter another device’s settings. Browser storage can be cleared, so keep a backup of scales you rely on.
These examples explain the tools. Your course policy determines how grades should be recorded. See the calculation methodology.