A starting amount, a monthly deposit, a rate and years in; the balance out, split into deposits and interest.
The sum behind a savings calculator is short, and any bank's website will do it for you. What a bank's version won't do is start on the numbers of the person you're helping, or ask them a question afterward. This page has one a teacher sent to her tenth-grade class, with three things to try before the next lesson. It teaches how saving works and promises nothing about a real account.
Who it's for
A parent with a teenager's first paycheck to talk about, a teacher covering compound interest, a financial coach between sessions. You're showing one person, or one class, what a habit is worth over time.
The page keeps nothing. Numbers typed in are gone on reload and answers to the questions aren't recorded, so the sample tells students to write theirs down and bring them. For choosing between real accounts, send people to the banks' own figures.
What a good one contains
- A start they recognize. $200 in the account and $50 a month is a tenth-grader's scale. The headline, "What $50 a month turns into", is the deposit the page opens on.
- Four inputs. Starting amount, monthly deposit, yearly rate, years.
- The balance, split in two. $7,660.66 after ten years is $6,200.00 put in and $1,460.66 of interest, on one bar in two colors. The split is the lesson.
- A sentence that sizes the interest. "Out of every $100 at the end, $19 is interest." It changes with the inputs.
- Bars that grow year by year. Deposits rise in even steps while the interest on top gets thicker each year. That widening band is compounding, drawn.
- How it's worked out. Interest added once a month at a twelfth of the yearly rate, deposits at the end of each month. Two calculators that disagree usually differ here.
- A warning about the rate. The page holds 4% still for ten years. No bank will, and the page says so, next to what it leaves out: tax, fees and rising prices.
- Something to try. Three questions that can only be answered by changing the numbers.
Questions do the teaching
A calculator on its own gets one glance. Give the reader a reason to move the inputs. Set the rate to 0 and they see how much was theirs all along. Double the sample's years and the money put in roughly doubles, from $6,200 to $12,200, while the interest goes from $1,460.66 to $6,583.25.
Pick a starting rate you can defend, and say where it came from. A page that opens on 10% teaches the wrong lesson about a savings account.
How to send it
As an open link. A class handout holds nobody's real money, and thirty students will open a link that asks for nothing. Add a password if it starts on someone's actual savings.
Every page you publish gets one link that opens in any browser. You choose who can open it: anyone with the link, anyone with the password, or only the people and company domains you name, who sign in with Google or Microsoft. Change the page later and the link stays the same.
