Nepali tool

BS ↔ AD date converter

Bikram Sambat is not a fixed offset from AD, so this uses a verified lookup table rather than a formula that quietly drifts.

Nothing you type is sent anywhere. This runs entirely in your browser — no upload, no server round-trip.

BS → AD AD → BS

Enter a Gregorian date

Year (AD)

Month

Day

Sharing the URL after converting a date shares that exact conversion — the link encodes the date and the direction, not just the tool.

How to use it

1

Pick a direction

Choose "BS to AD" or "AD to BS" at the top.
2

Choose year, month and day

Each dropdown only offers real dates — the day list adjusts automatically to the month you pick, so an invalid date can't be selected.
3

Read the result

The converted date appears immediately, with the day of the week and the Nepali month name in both Devanagari and romanised form.

Questions people ask

What years does this cover?

Bikram Sambat 1975 to 2099 (roughly 1918 to 2043 in the Gregorian calendar). That comfortably covers anyone alive today plus a couple of decades in each direction.

Why not just use a formula?

Because there isn't one that works. Unlike the Gregorian calendar, where every month's length is fixed and leap years follow a simple rule, Bikram Sambat month lengths are set from astronomical calculations and don't follow a fixed pattern — the only way to convert correctly is a verified lookup table, which is what this tool uses.

How was the data verified?

Cross-checked month-by-month against a second, independently maintained dataset, then verified against real published calendar dates at three separate checkpoints. Full details are in the tool's source code comments, including the one discrepancy that was found and how it was resolved.

What happens if I pick a date outside the supported range?

You can't — the year dropdown only lists years the underlying data actually covers, so there's no way to submit an unsupported date by accident.

Why Bikram Sambat can't be converted with a formula

The Gregorian calendar most of the world uses is simple to convert by rule: every month has a fixed length except February, and February's length follows one clean exception (divisible by 4, except centuries, except centuries divisible by 400). Bikram Sambat doesn't work that way. Its month lengths come from lunisolar astronomical calculations — the actual position of the sun — and range from 29 to 32 days without a fixed pattern from year to year. There is no formula that reproduces this correctly, which is exactly why a lookup table verified against real published calendars is the only trustworthy approach, and why so many quick BS↔AD converters online are quietly wrong for at least some dates.

When you'd use this

Converting a birth date, citizenship document or land record between the calendar it was recorded in and the one a form or system expects. Working out what a Nepali holiday or anniversary date falls on this Gregorian year. Checking a deadline or appointment given in the other calendar. Anywhere a mistaken date genuinely matters — paperwork, travel, legal documents — rather than a rough estimate.

Limitations

Supported years are Bikram Sambat 1975 to 2099 (roughly 1918 to 2043 AD). Dates outside that range aren't offered in the dropdowns at all, rather than being accepted and silently converted wrong.