What is the GMT to PST Converter?
This tool converts a time given in Greenwich Mean Time (GMT/UTC) to Pacific Standard Time (PST). PST is the standard winter time zone for the US and Canadian Pacific coast (e.g. Los Angeles, Vancouver), and it sits 8 hours behind GMT. Note: during summer, the Pacific coast observes Pacific Daylight Time (PDT = GMT − 7); this calculator computes the standard PST offset of −8 hours.
How to use it
Enter the GMT hour (0–23) and minute (0–59). The calculator subtracts 8 hours and automatically handles cases where the result falls on the previous day. The answer is shown on a 24-hour clock plus a decimal-hour value for spreadsheets.
The formula explained
The conversion is simply PST = GMT − 8 hours. To keep the result within a 24-hour range, we add 24 and take the remainder when dividing by 24:
$$\text{PST} = \left(\left(\text{GMT Hour} \times 60 + \text{GMT Minute}\right) - 8 \times 60 \bmod 1440 + 1440\right) \bmod 1440$$Minutes never change because the offset is a whole number of hours. Equivalently, working in minutes:
$$\begin{gathered} \text{PST}_{\min} = \Big(\big(M - 480\big) \bmod 1440 + 1440\Big) \bmod 1440 \\[1.5em] \text{where}\quad \left\{ \begin{aligned} M &= \text{GMT Hour} \times 60 + \text{GMT Minute} \\ \text{PST Hour} &= \left\lfloor \tfrac{\text{PST}_{\min}}{60} \right\rfloor \\ \text{PST Minute} &= \text{PST}_{\min} \bmod 60 \end{aligned} \right. \end{gathered}$$
Worked example
Suppose it is 15:00 GMT. Subtract 8 hours: \(15 - 8 = 7\), so it is 07:00 PST the same day. Now take 04:30 GMT: \(4 - 8 = -4\), which wraps to 20 (i.e. \(-4 + 24\)), giving 20:30 PST on the previous day.
FAQ
Is PST the same as PDT? No. PST (winter) is GMT − 8; PDT (summer daylight saving) is GMT − 7. This tool uses the fixed PST offset.
Why does the date sometimes change? Because PST is behind GMT, early-morning GMT times can fall on the previous calendar day in PST.
Is GMT the same as UTC? For everyday conversions, yes — they are effectively identical.
