JST vs PST time zone comparison

How JST and PST compare

Japan Standard Time runs seventeen hours ahead of Pacific Standard Time during the US winter and sixteen hours ahead during US daylight saving (PDT). San Francisco to Tokyo is one of the heavily-trafficked trans-Pacific tech corridors and one of the easier wide-gap pairs to coordinate, because the 17-hour difference creates a clean morning-Pacific-to-morning-Tokyo-next-day overlap. When San Francisco is at 5 PM, Tokyo is at 10 AM the next day. When Tokyo is starting at 9 AM, San Francisco is at 4 PM the previous day. The pragmatic shared window is the late-afternoon Pacific to mid-morning Tokyo slot: 4-6 PM Pacific is 9-11 AM Tokyo the next day. This is a clean handoff: California writes up the day's work at end-of-day, Tokyo picks it up at office open the next morning. Japan does not observe daylight saving, so the gap shifts from 17 hours in California winter to 16 hours in California summer. Tokyo's traditionally long working culture historically allowed late-evening calls (9 PM JST and later), but the modern post-pandemic workplace has tightened up on after-hours work. The corridor is well-traveled by gaming (Nintendo, Sony PlayStation, Square Enix), semiconductors (TSMC, Samsung via Tokyo HQs, Sony Semiconductor), and venture capital (SoftBank Vision Fund Tokyo HQ).

Working-hour overlap

Clean overlap from 4-6 PM Pacific (9-11 AM JST next day), with 4 PM Pacific the typical anchor for SF-Tokyo coordination.

When to schedule

Default to 4 PM Pacific (9 AM JST next day in winter, 8 AM JST next day in summer) for synchronous calls. Tokyo gets the meeting at their morning, California gets it at end-of-day. For asynchronous workflows, the standard is California end-of-day to Tokyo office-open: write up at 5 PM Pacific, Tokyo picks up at 10 AM next day. For one-off urgent calls, 5 PM Pacific (10 AM JST next day) is widely accepted. Avoid morning-Pacific calls; they always land in Tokyo's evening or middle-of-night.

Notable context

The gaming industry is the most visible SF-Tokyo corridor: PlayStation, Nintendo, Square Enix, and Capcom all run California publishing operations that coordinate with Tokyo development. The standard cadence is a weekly 4 PM Pacific (9 AM Tokyo next day) status sync, with major milestone calls running 5-6 PM Pacific for the Tokyo morning. Semiconductor companies (Sony Semiconductor, Renesas, Tokyo Electron) coordinate with Silicon Valley firms on a similar cadence, often with quarterly in-person travel because the technical depth of the conversations exceeds what asynchronous handoffs can sustain.