Tide times approximation

How this tide estimate works

This page gives a quick, low-precision tide rhythm for selected coastal cities. It is built for casual planning questions such as “is the tide roughly rising or falling later today?” rather than marine operations. The model uses a simplified semidiurnal lunar tide with a cycle of about 12 hours 25 minutes between alternating highs and lows. For each city, the timing starts from an estimated local lunar transit based on longitude, then applies a rounded phase lag for the local harbour or waterfront.

Real tide prediction is much more detailed. Official predictions combine many harmonic constituents, station datums, shallow-water effects, weather, river flow, pressure, wind setup, bathymetry, and local harbour geometry. This tool intentionally does not attempt that level of precision. The timing should be treated as approximate to about ±60 minutes, and the displayed height is only a rough range-based shape around mean sea level.

The 20 city reference ranges are rounded from public tide tables and station datum material, including NOAA CO-OPS for United States stations and UK Hydrographic Office Admiralty tide table material where applicable. For boating, anchoring, coastal walks, swimming, flood risk, port work, or any safety-critical use, check the official national hydrographic service, harbour authority, or local tide gauge before acting.

Need daylight as well as water level? Pair this with the sunrise and sunset table.