Tax, Time & Days Calculator
Three calculations you need at work, in one place: Japanese consumption tax, hours and dates. Answers appear as you type — no calculate button.
Enter an amount to get the pre-tax price, the tax, and the tax-inclusive total. This uses Japan's consumption tax (a sales tax / VAT) — 10% standard, 8% reduced rate for food and newspapers. Go from pre-tax to tax-inclusive or work backwards. Invoices that mix 10% and 8% can be totaled in the table below.
Calculate consumption tax
In Japan the law does not fix how to round the tax — each business chooses (rounding down is most common).
Total an invoice with mixed tax rates
| Item (optional) | Amount | Rate |
|---|
| Rate | Taxable amount (pre-tax) | Tax | Tax incl. |
|---|
Work out hours worked from clock-in and clock-out times. You can also add or subtract time ("what time is 7 h 30 min after 9:00?") and total a month of hours. Enter durations as "7:30", "7.5", "7h30m" or "45m".
Calculate hours worked
If clock-out is earlier than clock-in, it is treated as an overnight shift.
Add or subtract time"What time is 7 h 30 min after 9:00?"
Enter the duration as "7:30", "7.5", "7h30m" or "90m".
Add up hoursPaste a spreadsheet column straight in
Count the days between two dates. You can also find the date N days from now. Days can be counted as business days excluding weekends and Japanese public holidays, which is handy for deadlines and delivery dates in Japan.
Days between two dates
Date before or afterFind a deadline or due date
Business days apply only when the unit is "days". The base date itself is not counted; the next business day is day 1.
"Months" and "years" keep the same day of the month. If that day does not exist, the last day of the month is used (1 month after Jan 31 is Feb 28).
Japanese public holidaysThe holidays used for the business-day calculations above
What this tool can do
HANEKeisan is a free calculator for three things you often need at work in Japan: consumption tax, hours and dates. No install and no sign-up required. All calculations run inside your browser, so the amounts and dates you enter are never sent to or stored on a server.
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💰Consumption tax both ways
Add tax to a pre-tax price, or work back from a tax-inclusive price to the net price. Supports Japan's 10% standard rate and 8% reduced rate, plus past rates of 5% and 3%.
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🧾Invoice totals by tax rate
Invoices that mix 10% and 8% items are totaled per rate to get the tax. As required for qualified invoices under Japan's invoice system, tax is rounded only once per rate.
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⏱Work hours and time math
Get hours worked from clock-in, clock-out and break times, including overnight shifts. Add or subtract time ("7 h 30 min after 9:00"), total hours and convert to decimal.
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📅Days and business days
See the time between two dates in days, years/months/days, weeks and business days. Business days exclude weekends and Japanese public holidays — useful for deadlines and delivery dates.
How to use it (3 steps)
- Choose what to calculateSwitch between "Tax", "Time" and "Days" with the tabs at the top.
- Fill in the highlighted boxesInput areas are marked with a colored line on the left. There is no button to press — results update as you type.
- Check the "Answer"The answer appears in large type right below the inputs. Use the copy button to paste it into documents or emails.
When it comes in handy
Checking the tax on quotes and invoices
Calculate from either the pre-tax or the tax-inclusive amount. For invoices with mixed rates, use the totals table.
Working out the net price from a tax-inclusive price by simply dividing by 1.1 on a calculator can leave rounding errors. This tool fixes the tax-inclusive amount first, works back to the net price, and treats the difference as the tax, so the totals always add up.
Also, on qualified invoices in Japan, tax must be rounded only once per tax rate per invoice. Rounding each item and adding them up is not allowed. The totals table follows this rule.
Totaling work hours
Enter clock-in, clock-out and break times to get hours worked — overnight shifts included.
Hours worked are shown both as h:mm and in decimal hours for payroll — 7 h 30 min is 7.5 hours. Enter an hourly wage to see the pay for that time.
To add up a month of hours, use "Add up hours". You can paste a spreadsheet column directly; each line is read and totaled.
Note that under Japanese labor rules working time is in principle counted to the minute, and rounding down each day is not allowed. Use the rounding option only for internal estimates.
Counting days to a deadline
Find the date N days from now and the number of business days excluding weekends and holidays.
Use it to check how many days remain until a filing deadline, a payment due date or a vehicle inspection expiry. Counting business days (excluding weekends and holidays) shows how much time you really have — "only 3 business days left". You can also choose whether the Japanese New Year break (Dec 29 – Jan 3) counts as days off.
Holidays are calculated under Japan's Act on National Holidays, including substitute holidays when a holiday falls on a Sunday and "citizens' holidays" (a weekday sandwiched between two holidays). Vernal and Autumnal Equinox Days depend on astronomy, so calculated dates are shown; they are officially announced in the government gazette in February of the previous year, so dates for future years may change.
We make no guarantee as to the accuracy or completeness of the explanations on this page or the results of this tool. Tax rounding methods, the treatment of working hours and holiday dates may differ due to changes in law or agreements with business partners; the equinox days in particular are calculated estimates. For tax filings, payroll, contracts and other formal procedures, always check the latest laws and official gazette, or consult a professional such as a tax accountant or labor and social security attorney. See our Terms of Use and Privacy Policy for details.