Some costs arrive as one lump sum: an annual insurance premium, a six-month membership, a ten-week course. This calculator takes that single amount and spreads it evenly over the period it covers, so you can see what it works out to per day, per week, per month and per year.
It is deliberately simple. It handles one cost at a time and does not build a budget. To add rent, food, bills and subscriptions into one daily figure, use the daily expense calculator or the monthly expenses calculator.
How the calculation works
You enter a total cost, a period length and a period unit (days, weeks, months or years). The calculator first turns the period into calendar days:
- Days are used as entered.
- Weeks are multiplied by 7.
- Months are multiplied by 365 ÷ 12, which is about 30.42 days on average.
- Years are multiplied by 365.
Then it divides:
The other figures are converted from the daily cost using the same conventions: per week = daily cost × 7, per month = daily cost × 365 ÷ 12, per year = daily cost × 365. Because every conversion uses the same day counts, the figures stay consistent with each other. A cost entered as one year always comes back as exactly that amount per year and one twelfth of it per month.
The result panel also shows the formula with your own numbers in it, for example "1,200 ÷ 365 days = 3.29 per day" (formatted in the currency you pick), so you can check the arithmetic yourself.
Worked examples
Example 1 – an annual insurance premium. Total cost 1,200 for 1 year.
Days = 365. Cost per day = 1,200 ÷ 365 ≈ 3.29.
Per week = 3.2877 × 7 ≈ 23.01. Per month = 1,200 ÷ 12 = 100. Per year = 1,200.
Example 2 – a six-month membership. Total cost 270 for 6 months.
Days = 6 × 365 ÷ 12 = 182.5. Cost per day = 270 ÷ 182.5 ≈ 1.48.
Per week ≈ 10.36. Per month = 45. Per year = 540.
Example 3 – a ten-week course. Total cost 450 for 10 weeks.
Days = 10 × 7 = 70. Cost per day = 450 ÷ 70 ≈ 6.43.
Per week = 45. Per month ≈ 195.54. Per year ≈ 2,346.43.
The yearly figure in the last example does not mean the course costs that much in a year. It shows what the same rate would add up to if it continued for a full year. That kind of figure is useful when you want to compare a short commitment with something that is normally priced per year.
Why use average months?
Real months have 28 to 31 days, so a monthly bill does not cost exactly the same per day in February as in March. Using 365 ÷ 12 days for every month smooths that out and keeps weeks, months and years in proportion. The trade-off is that the result will not match one specific calendar month to the cent. Leap years are not modelled either; a year is always 365 days.
A way to look at it
A lump sum is easy to remember as one big number and easy to forget once it is paid. Turning it into a daily amount puts it on the same scale as the small things you pay for every day. Neither scale is more honest than the other. They simply make different costs easier to set side by side.