Japanese yen to Singapore dollars, in your head
One rule, the error band that comes with it, and the point at which it stops being the right rule. Updated from the live rate feed.
Yen to Singapore dollars. Accurate to within 2.1% at today's rate, which means it reads about 2.1% dearer than the real price.
The ladder
The middle column is what the rule gives you standing in a market. The right column is the real number, so you can see exactly where the shortcut costs you.
| Japanese yen | Rule of thumb | Actual |
|---|---|---|
| ¥50 | S$0.417 | S$0.408 |
| ¥100 | S$0.833 | S$0.816 |
| ¥200 | S$1.67 | S$1.63 |
| ¥500 | S$4.17 | S$4.08 |
| ¥1,000 | S$8.33 | S$8.16 |
| ¥2,000 | S$16.67 | S$16.32 |
| ¥5,000 | S$41.67 | S$40.8 |
| ¥10,000 | S$83.33 | S$81.61 |
| ¥20,000 | S$166.7 | S$163.2 |
Going the other way
Useful at the ATM, where you choose an amount in Singapore dollars and want to know what lands in your hand.
| Singapore dollars | Japanese yen |
|---|---|
| S$1 | ¥122.5 |
| S$5 | ¥612.7 |
| S$10 | ¥1,225 |
| S$20 | ¥2,451 |
| S$50 | ¥6,127 |
| S$100 | ¥12,254 |
What catches people out in Japan
Yen has no subunit in practice, so every price is a whole number and the arithmetic is cleaner than it looks. Cash is still expected in small restaurants and at shrines.
When this rule stops working
Rules of thumb rot quietly. This one holds while the rate stays roughly between 115 and 125 JPY to the Singapore dollar. Outside that band a different divisor becomes the better one to memorise. We regenerate this page from the live rate feed, so the date above tells you how fresh the number is — if you are reading this a long way after August 2026, check it before you rely on it.
Or skip the arithmetic entirely
RoamRate does this conversion with no signal, in one hand, on a number pad built for a thumb. Free for SGD; JPY and 150+ other currencies unlock for $4.99, once.
Download on the App Store