Yen quote conversion: why the pip is $6.70, not $10
1.00 lot is 100,000 USD. A 0.01 yen pip on that notional is 1,000 JPY. Divide 1,000 JPY by USDJPY (about 149) and you get roughly $6.70. At 150.00 the pip is $6.67; at 140.00 it is $7.14. Using $10 will understate lots and overstate dollar risk depending on which way you err, and both errors are common.
Typical spread is 0.2 to 0.7 pips. Daily ATR is 90 to 155 pips, larger than EURUSD, because the US-Japan rate gap and MoF "currency check" headlines are binary. Handles at 149.50, 150.00, 150.50 are intervention conversation magnets, not just round numbers.
Tokyo 00:00, Gotobi 00:55, and the Treasury open
Tokyo 00:00 to 03:00 UTC is a real session for this pair, unlike euro. Gotobi fixing near 00:55 UTC can shove 20 to 40 pips. The second engine is the US Treasury cash open 12:30 to 16:00 UTC, when 10-year yields drag USDJPY tick for tick.
Unscheduled BoJ/MoF intervention is the gap risk that no ATR stop fully contains. connect your MT5 account to Venasri and flatten or hard-reduce when yen headlines hit the economic calendar as "intervention warning" even if the folder is orange, not red.
The $100,000 formula uses 6.70, not 10
lots = risk dollars / (stop pips × 6.70). At $1,000 and 30 pips: 1000 / (30 × 6.70) = 4.98, matching the 4.95 lot reference. At 0.50% that is 2.47 lots. A 12 to 20 pip scalp stop is only sane during Tokyo or NY yield hours, not through an intervention print.
If your calculator still has pip value locked at $10, USDJPY size is wrong. Set pip value to 6.70 in the Half-Kelly Lot Size Calculator & Equity Guard and recompute every time the pair travels a big figure, because $6.40 at 156.00 is not $7.10 at 141.00.
Size the yield session, not the intervention fantasy
Trade Tokyo open or US Treasury hours at 00/50 yen handles, H4 aligned with yields. Intraday stops 28 to 45 pips. Swing 70 to 120. Never use a 12-pip stop when 150.00 is in play and officials are talking.
Gate entries with the Pre-Trade AI Confluence Checklist: yield direction, 150 handle distance, spread under 0.7, and no BoJ window. USDJPY pays the rate differential. It confiscates people who fade MoF with euro lot math.
