Tide Time Offset Calculator
Apply published time corrections from a NOAA primary tide station to estimate high/low tide times at a secondary station.
Result
- Primary HIGH time14:30
- Primary LOW time08:00
- HIGH time correction+25 min
- LOW time correction+20 min
- Secondary HIGH time14:55
- Secondary LOW time08:20
- Primary HIGH height5.2 ft
- Primary LOW height0.4 ft
- Height ratio0.850
- Secondary HIGH height4.42 ft
- Secondary LOW height0.34 ft
- Primary tide range4.80 ft
- Secondary tide range4.08 ft
Step-by-step
- Secondary HIGH = primary HIGH + 25 min = 14:55.
- Secondary LOW = primary LOW + 20 min = 08:20.
- Secondary heights = primary × ratio (0.850): HIGH 4.42 ft, LOW 0.34 ft.
How to use this calculator
- Look up the next high and low tide at your nearest NOAA primary station (tidesandcurrents.noaa.gov).
- Get the time and height corrections for your secondary station from the NOAA Tide Tables Table 2 or your chart's tidal-station data.
- Enter primary times in 24-hour HH:MM and corrections in minutes (positive = later, negative = earlier).
- Height ratio < 1 means smaller tides at your station; > 1 means larger range.
About this calculator
NOAA / CO-OPS publishes a primary network of ~210 US tide stations with continuously-measured water levels. Thousands of "secondary" stations exist as published time-and-height corrections relative to the nearest primary — typical corrections are ±5-90 minutes in time and a height ratio between 0.5 and 1.5. This calculator applies those corrections to predict secondary-station tides from a known primary prediction. Limitations: time/height corrections are themselves long-period averages and may be off by 5-15 minutes during extreme weather, near solstices, or in shallow estuarine waters where the tide propagation is more dispersive. For navigation, always cross-check NOAA Tide Tables and your chart-correction supplement.