HOW THE TOOLS WORK
How our planners work
Every planner works from what you enter. The method is shown on each tool page, so you can follow how a result was reached.
Your numbers, not ours
The planners calculate from your own figures: your date, your guest count, your budget, your rates. We do not fill in typical costs or averages for you.
Where a planner offers a starting list, such as checklist tasks or group photos, you choose what to keep, and you can add your own.
Facts from official sources
When a planner relies on a fact from outside, such as the official service for changing your name or how the sunset time is worked out, its page lists the official source and the date we last checked it.
Sources are governments, regulators, recognised professional bodies or the maker's own published sheet. If no official source exists, the planner does not guess a value.
Rounding and dates
Each tool page explains how it rounds. Things you buy are rounded up so you do not run short, such as whole bottles; things you share out are rounded down, such as whole cake slices. Money is kept to the cent.
Dates are worked out in whole calendar days, so a plan does not shift with your time zone or a change to daylight saving time.
How we test the tools
Every planner has a worked example, written before the tool was built, and automatic tests check that the tool still gives exactly that answer after every change.
The tests also cover edge cases such as leap years, the end of a month, the clocks changing, empty or invalid entries, and printing.
This page describes the site as it works today. It changes when the site does.