Last updated: March 2026
TideCheck provides free tide predictions for over 6,400 stations in >175 countries worldwide. Our predictions are calculated using harmonic constituent analysis — the same proven mathematical method used by national hydrographic offices and maritime agencies around the world.
Each station's tidal signature is decomposed into astronomical components (solar, lunar, and their interactions), which are then recombined to produce tide height predictions at any point in time. This is supplemented by sunrise/sunset, moon phase, and solunar activity data.
TideCheck's harmonic constituent data comes from three sources:
Harmonic constituents for US coastal stations are sourced from the NOAA Center for Operational Oceanographic Products and Services (CO-OPS). This data is in the public domain as a product of the US federal government.
Includes both reference stations (direct harmonic prediction) and subordinate stations (time/height corrections applied to a nearby reference station).
International tidal constituents are sourced from the TICON-4 (Tidal Constituents from Observations and Numerical models) database, published by SHOM (Service Hydrographique et Océanographique de la Marine).
TICON-4 data is released under the Creative Commons Attribution 4.0 International (CC-BY-4.0) license. DOI: 10.17882/109129.
Citation: Lefèvre F., Carre H., Faucher C. (2025). TICON-4 Tidal Constituents from observations and numerical models. SEANOE.
Additional stations in underserved regions are derived from the FES2022 (Finite Element Solution) global ocean tide atlas, distributed by AVISO+ / CNES.
FES2022 is produced by Noveltis, Legos, and CLS and provides harmonic constituents on a 1/30° global grid. We extract constituents at specific coastal locations using bilinear interpolation. Used under the AVISO+ Standard License, which permits commercial derivative works with attribution.
Generated using AVISO+ Products. FES2022 was produced by Noveltis, Legos and CLS and distributed by AVISO+.
TideCheck uses harmonic constituent analysis — the internationally recognized standard method for tidal prediction, as specified by the International Hydrographic Organization (IHO). This is the same fundamental approach used by national hydrographic offices worldwide, including NOAA (United States), SHOM (France), UKHO (United Kingdom), and AHS (Australia).
At its core, the method decomposes the complex rhythm of the tides into individual periodic components — each driven by specific gravitational interactions between the Earth, Moon, and Sun. These components (called harmonic constituents) are combined with high-precision astronomical calculations, including nodal modulation corrections on an 18.6-year lunar cycle, to reconstruct the full tidal signal at any point in time.
Our proprietary prediction engine implements a comprehensive set of tidal constituents — covering semi-diurnal, diurnal, long-period, and shallow-water harmonics — with full astronomical correction pipelines for solar and lunar orbital mechanics. The engine is purpose-built and has zero external dependencies, giving us complete control over accuracy and performance.
TideCheck maintains two categories of tide stations:
We continuously validate our predictions against official sources. For US stations, TideCheck predictions typically agree with NOAA's official published predictions to within ±3 minutes in timing and ±2 cm in height — well within the variability caused by weather and atmospheric conditions on any given day.
It's worth understanding what tidal predictions represent: they model the astronomical tide — the predictable, gravitationally-driven component of water level. On a calm day, this is remarkably accurate. However, actual water levels are also influenced by:
No harmonic prediction — including those from official government agencies — accounts for these real-time variables. For this reason, our predictions are designed for planning coastal activities (surfing, fishing, diving, beach visits) and are not intended for navigation. See our Disclaimer for full details.
Because harmonic analysis is based on astronomy — which is deterministic and predictable — tidal predictions maintain their accuracy years into the future. The astronomical forces driving the tides follow precise, known cycles. A prediction for next week is essentially as accurate as one for a year from now, assuming stable local conditions.
The main source of long-term drift is gradual sea level change and shifts in local bathymetry, which occur over decades rather than days. For practical planning purposes, our predictions are reliable for any date within the current year and well beyond.
Tide heights are meaningless without a reference level. TideCheck supports three internationally recognized vertical datums:
You can switch between datums on any station page using the datum selector. All times are displayed in each station's local timezone.
Beyond tide predictions, TideCheck computes a range of supplementary data for each station:
TideCheck is built on modern edge infrastructure for fast global performance. Every prediction is computed in real-time on demand — we do not serve pre-generated tables or cached results. This means you always get fresh calculations based on the latest constituent data in our system.
Our prediction engine is a standalone, purpose-built computation library with zero runtime dependencies. It runs entirely on edge servers close to you, with typical response times under 50ms worldwide.
For questions, corrections, or data source inquiries, please visit our Contact page.