Prorated Rent (Hiwari) Calculator
＋More features: total your initial move-in costs
Get the total upfront payment including shikikin and reikin
Enter the deposit and fees as “months of rent”, as written in your contract or quote (the rent and move-in date come from the form above; proration uses the actual-days method).
When you move into or out of a rental in Japan partway through a month, that month’s rent is prorated — hiwari in Japanese. This tool shows the two methods commonly used in Japanese leases side by side (dividing by the actual days of the month, or by a fixed 30 days), and can also total your initial move-in costs including Japan-specific fees such as shikikin (security deposit) and reikin (key money). Use it to check the figures on your contract or quote.
How to use
- Enter the monthly rent (add the common-service fee if it is prorated too).
- Choose move-in or move-out and pick the date (today’s date is preset).
- The prorated amounts by both methods appear side by side the moment you choose. No button needed.
How it is calculated
- Actual-days method: prorated rent = monthly rent × days charged ÷ days in that month (28–31)
- Fixed 30-day method: prorated rent = monthly rent × days charged ÷ 30 (always divided by 30 regardless of the month’s length)
- For a move-in, the days charged run from the move-in date to the end of the month; for a move-out, from the 1st to the move-out date.
- Example: rent 80,000 yen, moving in on July 20 (July has 31 days) → 12 days charged. Actual-days method: 80,000 × 12 ÷ 31 = 30,967 yen / 30-day method: 80,000 × 12 ÷ 30 = 32,000 yen
- If the 30-day method would exceed the monthly rent, it is capped at the monthly rent.
Sources and assumptions
- This is plain arithmetic. The proration method and rounding are not standardized by law in Japan — they follow the individual lease agreement.
Assumptions and notes
- February (28/29 days) shows the biggest gap between the methods. With the actual-days method the per-day price is higher in February and lower in 31-day months.
- On top of the move-in month’s prorated rent, you are usually asked to pay the following month’s rent in advance as part of the initial costs. Plan your budget with both together.
- For move-outs, some contracts do not prorate at all and charge the full month (for example with a one-month-notice clause).
Frequently asked questions
Which is more common, the actual-days method or the 30-day method?
Both are widely used in Japan. The rent-proration clause in your lease takes priority; if there is no such clause, ask the management company.
Are common-service and management fees prorated too?
It depends on the contract. Many leases prorate them the same way as rent, but some charge the full amount. If they are prorated, calculate with the rent and fees combined.
Which move-in date works out cheapest?
With a prorating contract, the closer your move-in date is to the start of the month, the more “prorated rent + advance rent” you pay up front; the closer to the end, the less. To be sure, compare including any free-rent period and the overlap with rent on the place you are leaving.