Tide times and heights for any coastal place
High and low water times, the level right now and a tide curve two weeks ahead for the place you choose. Computed in your browser, so it keeps working without a connection.
How to read it
A port, town or village on the coast.
Level now and the next waters.
Draught and depth give the gate.
Pick a place and see when the water comes in and goes out
Tides are computed from a global model, not from tide-gauge observations. In narrows, estuaries and rivers the real water differs: it arrives later and rises higher. Heights are relative to mean sea level; chart datum is estimated and is not official. For navigation use corrected tide tables and hydrographic office charts.
Tidal model: GOT4.10c, R. Ray, NASA Goddard Space Flight Center — public domain. The arithmetic is verified against published NOAA CO-OPS predictions.
Features
What you can do
- Find high and low water times for today and two weeks ahead
- See the level at this moment
- Tell whether it is springs or neaps
- Work out under-keel clearance and the tidal gate
- Export the waters to a calendar or a table
- Solve a tidal problem from almanac figures
How this differs from a tide website
In where the arithmetic happens. Tide sites keep the constants on their server, so the page is blank without a connection — and the tide matters exactly where the connection is not: in a cove, on the grounds, near a bar. Here the constants ship with the tool and the sum runs in your browser, so a page opened once keeps answering. The second difference is that the tool does not abandon you at the table: the same waters flow straight into under-keel clearance and the tidal gate. And the third, usually left unsaid: this is a MODEL, not station observations, and in narrows, estuaries and rivers it departs from reality. We say so plainly and show which point was used and how far it is from yours.
Frequently asked questions
How close is the predicted water to the real water?
The arithmetic itself is checked against somebody else's data: across six NOAA stations with different tidal forms it differs from their own prediction by 1 to 9 centimetres RMS. But that is the accuracy of the CALCULATION for given constants. The constants themselves are coarser: they come from a global model on a half-degree grid, roughly 55 kilometres, and in narrow bays, estuaries and rivers the real tide differs more — the water arrives later and rises higher than in the open sea nearby.
What are the heights measured from?
Mean sea level, because that is how the model is built. Tide tables and charts give heights from chart datum (LAT), which is a different number. In the clearance mode the tool converts to chart datum itself, estimating that datum by sweeping the full 18.6-year nodal cycle. The estimate is approximate: an official chart datum is set by a hydrographic office, not derived from a model.
Why does almost nothing move on the Black Sea?
Because the tide there really is close to nothing — about ten centimetres. Levels on the Black and Baltic coasts are driven mainly by wind and pressure rather than the Moon, and a tide table explains little there. The tool shows what is there and does not invent a range that does not exist.
Can I navigate on this?
As a reference and for planning, yes. As grounds for crossing a bar or passing under a bridge, no. Corrected tide tables and hydrographic office charts exist for that and remain the only admissible source. The navigation part of the tool does what you would otherwise do with a pencil, and it is happy to be fed figures from the book.
What does "nearest model point, N km" mean?
The model is a grid and its nodes do not sit on your berth. The tool takes the nearest node and shows the distance, so you can judge how much the answer is about your place. A few kilometres along an open coast change almost nothing; the same few kilometres up a river or into a narrow inlet change a great deal.
What are springs and neaps?
Springs are new and full moon, when the Moon and the Sun pull together and the range is largest; neaps are the quarters, when it is smallest. The tool decides this from the day's range against the place's own span rather than from the lunar phase: where the tide is diurnal, phase and range disagree, and an answer by phase would be confidently wrong.
Why keep the manual-entry modes?
Because that is work from the book: height at a time, the inverse problem, reducing a standard port to a secondary one, prediction from your own constants. It is set in examinations and done at sea, and a model must not replace it. What changed is that the figures now have a source — today's waters for the chosen place drop into the fields with one button.
We can! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.
