A tide table looks intimidating at first glance — a grid of numbers, abbreviations, and times that seems designed to confuse. But once you understand the logic behind it, reading a tide table becomes second nature. This complete guide will teach you everything you need to know, from the basic concepts of tidal movement to reading professional maritime tide predictions.
What Is a Tide Table?
A tide table is a published set of daily predictions showing the times and heights of high and low tides at a specific location. These predictions are calculated from decades of tidal observations combined with astronomical data about the positions of the moon and sun.
Tide tables are published for a full calendar year by government hydrographic offices such as:
- NOAA (USA) — tidesandcurrents.noaa.gov
- UK Hydrographic Office (UKHO) — admiralty.co.uk
- SHOM (France) — shom.fr
- Australian Bureau of Meteorology (BoM) — bom.gov.au
- Japan Meteorological Agency (JMA) — jma.go.jp
- Brazilian Navy (CHM) — marinha.mil.br
Each tide table is location-specific. A table for Sydney will be different from one for Melbourne, even though they're in the same country.
Key Tidal Terms You Must Know
Before reading any tide table, learn these fundamental terms:
| Term | Definition |
|---|---|
| High Water (HW) | The highest point of a tide cycle; also called high tide or preamar (PT) |
| Low Water (LW) | The lowest point of a tide cycle; also called low tide or baixamar (PT) |
| Tidal Range | The vertical difference in height between high and low water |
| Flood Tide | The rising tide — water level is increasing |
| Ebb Tide | The falling tide — water level is decreasing |
| Slack Water | The brief period of minimal tidal current near high or low water |
| Spring Tides | The strongest tides, occurring near new and full moons |
| Neap Tides | The weakest tides, occurring near first and last quarter moons |
| Chart Datum | The reference level (zero) from which tidal heights are measured |
| MLLW | Mean Lower Low Water — the US standard datum |
| LAT | Lowest Astronomical Tide — the Australian/UK standard datum |
Anatomy of a Tide Table: Column by Column
A typical tide table for a given day looks like this:
| Date | Time | Height | High/Low |
|---|---|---|---|
| 15 Jul 2026 | 03:42 | 4.8 m | HIGH |
| 15 Jul 2026 | 09:58 | 0.6 m | LOW |
| 15 Jul 2026 | 16:14 | 4.5 m | HIGH |
| 15 Jul 2026 | 22:27 | 0.9 m | LOW |
Reading Each Column
Date: The day the prediction applies to. Always check this — tides shift by approximately 50 minutes each day.
Time: The predicted time of the high or low water event. Always check whether the table is in local time or UTC/GMT. During daylight saving time, you may need to add 1 hour.
Height: The predicted water level at that moment, measured in metres or feet above the chart datum. A height of 0.0 m means the water is at the lowest possible astronomical level (LAT datum). Negative heights, though rare, indicate the water is below the theoretical minimum.
High/Low (H/L): Whether the event is a high or low tide. Some tables use arrows: ▲ for high, ▼ for low.
Understanding Tidal Range
The tidal range is simply High Water Height minus Low Water Height. For the example above:
- First range: 4.8 m − 0.6 m = 4.2 m (strong spring tide)
- Second range: 4.5 m − 0.9 m = 3.6 m
A large range means dramatic changes in the coastline — beaches may appear and disappear, rocks emerge from the sea, and tidal currents are powerful.
What Is the Tidal Coefficient?
Some European tide tables (particularly French and Portuguese ones) include a tidal coefficient (coeficiente) — a number from 20 to 120 indicating the strength of the tide:
| Coefficient | Type | Characteristics |
|---|---|---|
| 95–120 | Very strong spring | Maximum range, powerful currents |
| 70–95 | Spring | Large range, strong currents |
| 40–70 | Intermediate | Moderate range |
| 20–40 | Neap | Small range, weak currents |
How Tides Work: The Moon and Sun
Tides are caused by the gravitational pull of the moon (and to a lesser extent, the sun) on Earth's oceans.
- New Moon and Full Moon: The sun, Earth, and moon are aligned. Their gravitational forces combine, producing spring tides with the largest ranges.
- First and Last Quarter Moon: The moon and sun are at right angles to Earth. Their gravitational forces partially cancel, producing neap tides with smaller ranges.
- Perigee: When the moon is closest to Earth in its elliptical orbit. Tides are exceptionally strong — called King Tides in Australia and New Zealand.
Practical Examples: Planning Your Activity
Going Surfing
Check the tide table and note whether the tide is rising (flood) or falling (ebb) at your planned surf time. Most surf breaks have a preferred tidal state — usually mid-tide on a flood for beach breaks, or lower tide for reef breaks where more water can cause the wave to not break cleanly.
Going Fishing
Most species are most active during tide changes — the transition from ebb to flood or flood to ebb. Plan to be fishing in the 2 hours before and after high or low water.
Exploring Rock Pools
You want the lowest possible water. Look for days with a spring low tide (large range, low coefficient), and time your visit to arrive 30 minutes before the predicted low water so you can watch the pools emerge.
Boating and Kayaking
Avoid strong tidal currents by paddling during slack water — the 30–60 minute window around high or low water when currents are minimal. Always plan your return journey accounting for the tide direction.
Common Mistakes When Reading Tide Tables
- Ignoring daylight saving time — always verify whether the table is in local time or UTC.
- Using a table for the wrong location — tides can be very different just 20 km apart.
- Confusing height with depth — tidal height is measured from chart datum, not from the actual seabed depth.
- Ignoring weather effects — strong onshore winds and low atmospheric pressure can raise actual sea levels above predicted values by 0.5 m or more.
Check Your Local Tide Table at MaréAgora
Now that you know how to read a tide table, put your knowledge into practice. Check the live tide table for your location at MaréAgora — with predictions for 2026, moon phase data, sunrise/sunset times, and tidal coefficient information all in one place. Bookmark it before your next beach day.
Tidal prediction methodology follows internationally recognised standards from the International Hydrographic Organization (IHO). Actual sea levels may vary due to weather and oceanographic conditions.