The Finance Algorithm
§ Tool · tier 1 · independent

Interest-Free Period Calculator.

Understand and maximize your credit card's interest-free period

CalculatorFree, no signupOn-deviceupd May 2026
Inputs
Your numbers
15

Day your statement closes (1-28)

21

Usually 21-25 days after statement

16

When you make the purchase

$
$1k
%
20%

For comparison if you miss payment

Math updates live as you change inputs · AI runs on submit

Awaiting inputs

Move the sliders or type in the form on the left — the math updates live as you go. Click Get AI verdict when you want a written analysis.

Credit cards offer up to 55 interest-free days - but only if you pay in full. This calculator shows your actual interest-free period based on when you make purchases.

§ Worked examples

Real-world scenarios

Maximizing Interest-Free Days

Statement closes on 15th. Due date 21 days later (6th). $1,000 purchase made on 16th vs 14th.

Inputs

statement:15dueDays:21purchase1:16purchase2:14

Purchase on 16th: 51 days interest-free (appears on next statement). Purchase on 14th: only 22 days! For $1,000 at 20%, that 29 days difference saves $15.89.

§ FAQ

Questions Australians ask

§ Glossary

Plain-English definitions

Interest-Free Period
Time between purchase and due date when no interest is charged if paid in full.
Statement Closing Date
When your monthly statement is generated - purchases after this go on next statement.
Due Date
Deadline to pay your statement balance to avoid interest and late fees.