Why exchange rates change all day — and how Tokyo shops turn that into the number on the board
⚡ 30-Second Answer: FX rates move because of ①the interest-rate gap between the Fed and the Bank of Japan, ②trade balances, ③geopolitical risk, ④speculative and carry-trade flows, and ⑤real demand (travel and trade settlement). USD/JPY moves 0.5-1.5% on a normal day and 1-3% on central-bank days; over a 2-3 month booking window, plan for ±5-10%. Tokyo counters re-price only 1-3 times a day — the board is essentially "this morning's mid-market minus the shop's spread". For a one-week trip, the gap between a good shop and a bad one (1-2.5% downtown, 5-7% airport vs best) is bigger than the rate move during your stay — pick the shop, don't time the market.
Quick Reference
Value
Key drivers
Fed-BoJ rate gap, trade, geopolitics, carry trade
Typical daily move
0.5-1.0%
Big move days
1-3% (BoJ / Fed decisions, 8 meetings a year each)
2-3 month range
±5-10%
Shop re-pricing
1-3 times a day (small shops: once, in the morning)
Downtown spread
~1-2.5% below mid; airport 3-6%
Hedge
Wise/Revolut and Seven Bank ATMs price at the live rate
Last verified
September 2026
✓ Last verified: Sep 2026
📖8 min read
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Contents📖 ~9 min read
Exchange rates change continuously during forex market hours (Sunday evening UTC through Friday afternoon UTC) because the global forex market trades around the clock, with banks and institutions constantly updating bid/ask prices on supply, demand and news. Retail Japanese exchange shops re-price only 1-3 times a day, so the rate on a board can lag the live mid-market by hours. This page explains what moves the rate, why USD/JPY in particular swings so much, how a shop turns the wholesale rate into its board, and what all of that means for a tourist deciding when and where to exchange.
TL;DR
Forex trades 24/5 — Sunday evening through Friday afternoon UTC.
Retail shops update 1-3 times daily — they're not real-time.
The shop rate is "morning's mid-market minus a spread" — pre-built into the displayed number.
For tourists, shop choice beats timing — the daily move is smaller than the spread.
How does the global forex market work?
Three things drive continuous price changes:
1. Supply and demand
Every minute, dozens of major banks make currency trades worth billions of dollars. Those trades shift the bid/ask prices that determine the mid-market rate.
2. News and economic data
Interest-rate announcements (BoJ, Fed, ECB), GDP releases, unemployment numbers, geopolitical events — each causes immediate rate movements.
3. Carry trade and macro positioning
Hedge funds and institutions take long-term currency positions; their entry and exit moves the market.
The result: USD/JPY can move 0.3-1.5% in a single day, with some weeks seeing 3-5% movements.
Why does USD/JPY in particular swing so much?
USD/JPY is one of the most-traded pairs in the world, and its big moves come from a short list of causes.
The interest-rate gap is the main engine. Japan's policy rate remains far below the United States', and that gap feeds the carry trade — borrow yen cheaply, buy dollars, pocket the difference. When the gap widens, money flows out of yen and USD/JPY rises; when markets expect it to narrow, the trade unwinds and the yen strengthens quickly. Expectations move the rate before the central banks actually act.
Central-bank meetings are the biggest single-day events. The Bank of Japan and the Fed each meet eight times a year, roughly every six weeks. On decision days USD/JPY can move 1-3%, occasionally more. The BoJ announces around midday Tokyo time on the second day of its meeting; the Fed announces at 14:00 New York time, which is 03:00-04:00 the next morning in Tokyo.
Geopolitics and intervention. US-China trade headlines, Middle East tension and stress in global markets tend to push money into the yen as a safe haven. Japan's Ministry of Finance also intervenes directly when it judges the move too fast — and even the rumour of intervention can move the pair one or two yen in an afternoon.
US data releases. The monthly US jobs report (first Friday of the month, 21:30 Tokyo time) and CPI prints regularly move USD/JPY one to two yen within half an hour. Rates settle again a few hours later.
How fast do retail shops update?
Shop type
Update frequency
Wise / Revolut
Real-time at transaction
Major Japanese ATM (7-Eleven Seven Bank)
Real-time via card network
Dedicated Tokyo exchange chain (WCS, Dollar Ranger, Travelex)
1-3 times daily
Small pawn-shop / ticket-shop FX windows
Once daily (morning)
Hotel front desks
Once daily or less
The lag means the rate you see at a small Tokyo shop in the afternoon may reflect the morning's mid-market, not the afternoon's. If the rate has moved during the day, the shop rate is slightly stale — in your favour if the yen strengthened, against you if it weakened.
How does a shop actually set the day's rate?
The process behind the board is more mundane than most travellers expect.
Before opening. Staff check the mid-market rate — the big chains use Reuters or Bloomberg terminals, small shops use Yahoo Finance or the bank TTM fix — and take the Tokyo-open level as the day's reference. They add the shop's standard spread to build the WE BUY and WE SELL numbers and post them. The major chains sync the same figures to their websites; WCS and Dollar Ranger publish theirs online, which is why Yen Finder can track them.
Through the day. In dense clusters like Shinjuku West Exit or Ginza, staff watch the rival boards and adjust by a tenth of a percent or two to stay competitive. Inventory matters too: a counter sitting on too many dollars nudges its WE SELL rate to move them; one running short of yuan nudges its WE BUY rate to attract sellers. When the market jumps more than a yen in a day, the board simply falls behind for a while.
The spread is not the same for every currency. USD is thin because volume is huge; EUR and GBP are a little wider; the less a shop trades a currency, the thicker the margin. As a rough guide for a downtown counter:
Currency
Typical spread below mid
USD
~1-2.5%
EUR / GBP
~2-4%
KRW / CNY / TWD
~1.5-3% (tighter at specialist shops such as Shin-Okubo for KRW)
THB, VND, IDR and other exotics
~5-10%
Airport counters and hotel desks sit outside these bands at roughly 3-6% and 4-7% below mid regardless of currency.
Three timing quirks worth knowing. Monday morning boards can still reflect Friday's close, so if the yen weakened over the weekend the morning rate is briefly generous. During long holidays (Golden Week, Obon, New Year) shops run on skeleton staff and update less often. And from about 16:00, when London joins Tokyo, the mid-market tends to move most — late-afternoon boards are the ones most likely to be stale.
What does this mean for a tourist budget?
For a typical 7-day trip exchanging $1,500:
Factor
Size
On $1,500
One day's rate move
0.5-1.5%
¥1,100-¥3,400
Rate move across the whole week
1.5-3%
¥3,400-¥6,800
Gap between the best and worst downtown counter
1-2.5%
¥2,300-¥5,600
Gap between the airport and the best downtown counter
5-7%
¥11,000-¥16,000
Loss from exchanging at your home bank instead
4-6%
¥9,000-¥13,500
Shop choice is worth as much as, and usually more than, the rate move during your stay — and unlike the market, it is entirely under your control.
If you still want to hedge the timing: three rules
Split the exchange. Change part of your cash three or four days before the trip and the rest once you arrive. Two or three tranches give you an average rate and take the sting out of a bad day.
Stay away from the 24 hours before a BoJ or Fed decision. Look up the dates before you fly; if one lands during your trip, exchange before it or wait until the dust settles the next day.
Let the card do the timing. Card payments and Seven Bank ATM withdrawals with a Wise or Revolut card price at the live rate at the moment of the transaction, so they are far less exposed to the board lag than a cash exchange.
What this means for your trip
✅ Exchange in late morning (10:00-12:00) when shops have posted the day's rate and it is still fresh.
✅ For real-time rates, use Wise/Revolut card payments or a 7-Eleven Seven Bank ATM (network rate).
✅ Check the live mid-market before walking in — Yen Finder shows it, and WCS publishes its board online.
⚠️ Don't try to time the market on a one-week trip — the daily move is usually smaller than the spread.
⚠️ Don't re-exchange mid-trip because the rate moved — you pay the spread twice.
Frequently asked questions
Are forex markets really 24/5?
Yes — Sunday evening (UTC) through Friday afternoon (UTC). Individual exchanges have brief breaks, but the global market is continuous.
Why don't shops update in real time?
Operational cost. Real-time pricing needs automated systems; small shops post by hand. Wise, Revolut and Seven Bank ATMs have the infrastructure for it. Smart Exchange machines get one rate pushed from a central server two or three times a day.
When are forex rates most volatile?
Around BoJ/Fed/ECB announcements, during global market stress, and in the first hour after the European and US opens. The US jobs report (first Friday, 21:30 Tokyo time) is a reliable monthly jolt.
The yen is weakening — should I exchange now rather than wait?
Nobody, professionals included, calls short-term USD/JPY reliably. Over a 3-4 week booking window the pair usually moves ±1-3%; the airport-versus-downtown gap is 5-7%. Where you exchange matters two to three times more than when.
Should I time my exchange to a specific market hour?
For a tourist trip, no — the daily move is usually 0.3-1.5%, small relative to the shop spread. Optimise the shop, not the timing.
Can I ask the counter what mid-market rate they used?
At the major chains, yes — staff will usually tell you the day's reference rate if you ask. Shops that publish rates online are the most open about it.
Can I negotiate the posted rate?
Only on large amounts. From roughly $5,000 equivalent, a chain's branch manager may improve the rate by 0.2-0.5%. For everyday sums the board is the price.
Do forward contracts or crypto help a traveller?
No. Bank forward contracts are built for corporate sums (typically $50,000 and up), and routing USD through a stablecoin into yen stacks several fees and usually ends up worse than a decent counter.
What about the credit-card exchange rate?
Visa, Mastercard and JCB apply their network rate plus the issuing bank's foreign-transaction fee (often 2.5-3%); Wise and Revolut charge close to nothing above mid. That is a different mechanism from the shop board — see Wise vs Revolut vs your bank.