# Tide Table vs. Tide Chart: What Is the Difference?

> A tide table lists predicted times and heights of high and low water, while a tide chart usually plots the predicted water level as a curve through time. Both may be generated from the same harmonic prediction. The table favors exact values;...

Canonical URL: https://www.argo.net/tide-table-vs-tide-chart-what-is-the-difference/
Byline: ARGO.net Editorial Team
Published: 2026-08-25T12:53:21+00:00
Categories: Explainer, Oceans

![Tranquil coastal shoreline at low tide with calm blue ocean and distant horizon](https://www.argo.net/wp-content/uploads/2026/08/tide_chart_and_coastal_water_level.jpg)

A **tide table** lists predicted times and heights of high and low water, while a **tide chart** usually plots the predicted water level as a curve through time. Both may be generated from the same harmonic prediction. The table favors exact values; the chart makes the day's changing pattern easier to see.

Neither product should be confused with a nautical chart, which maps depths and navigation features. Everyday websites sometimes use "tide chart" as a general label for any tide prediction, so readers should check the displayed units, **station** and datum rather than relying on the page title.

## Tide tables organize high and low water

A traditional table gives a date followed by the predicted time and height of each high or low tide. This compact format makes it easy to answer a specific question, such as when the afternoon low occurs or how high the next morning's high tide is expected to reach.

NOAA explains that its [official tide tables](https://oceanservice.noaa.gov/facts/tide-tables.html) contain daily high and low predictions at thousands of locations. Digital services can display the same information for a chosen interval and export it in printable or machine-readable formats.

A table usually omits every intermediate water level. Users can see the turning points but must estimate what happens between them unless an hourly series is included. The format is efficient for trip planning when the critical threshold is near high or low water.

## Tide charts show the curve between extremes

A tide chart places time on the horizontal axis and water level on the vertical axis. Peaks mark high water, while troughs mark low water. The slope gives a visual sense of how quickly predicted water level is changing at each point in the cycle.

The curve makes mixed tidal patterns obvious. Two highs may have unequal heights, or one day may contain only one prominent high and low. A week-long chart also reveals the gradual expansion and contraction associated with spring and neap tides.

Reading a plotted value requires care. A phone screen may compress the axis and the cursor may round times or heights. When a precise clearance or depth calculation depends on a turning point, the accompanying table provides the cleaner numerical value.

Some commercial charts add weather, wave forecasts or fishing indicators. Those layers may come from different models and update schedules. The tide prediction itself should identify the responsible agency and station.

## Station choice controls accuracy

Tidal timing changes along a coast and within an estuary. A prediction for an ocean pier may differ from a marina several miles upstream. Select the station closest to the activity only when it represents the same connected waterway and local tidal behavior.

NOAA's [Tide Predictions station search](https://tidesandcurrents.noaa.gov/tide_predictions.html) accepts a station name, identification number or coordinates. Reference stations have long observations, while subordinate stations use adjustments related to a nearby reference station.

A nearby station can still be misleading across an inlet or on the opposite side of a headland. Narrow channels introduce delays and shallow flats may drain differently from deeper water. Local harbor authorities can identify the prediction convention used for navigation.

## The vertical datum gives heights meaning

Predicted height is measured relative to a stated reference surface called a **tidal datum**. U.S. tide products commonly use **Mean Lower Low Water**, the average of the lower low water of each tidal day over an official 19-year epoch. A value of zero refers to that datum rather than the seafloor.

Other products may use Mean Sea Level, Mean Low Water or a chart datum defined by a national hydrographic office. Comparing numbers from different sources without checking the datum can introduce an error large enough to affect clearance or coastal-flood interpretation.

NOAA's [tidal datum information](https://tidesandcurrents.noaa.gov/datum_options.html) explains the reference levels available at **water-level station**s. Nautical chart depths use chart datum, while bridge clearances may use another reference. The needed conversion depends on the purpose.

Units also require attention. Heights may appear in feet or meters and times may use local standard time, daylight time or UTC. A correctly read value with the wrong time zone can be as hazardous as choosing the wrong station.

## Predictions differ from observations

**Tide predictions** represent the astronomical component derived from recurring motions of Earth, Moon and Sun. Wind, atmospheric pressure, river flow and waves can raise or lower the actual water. The difference is especially important during storms or coastal flooding.

A water-level station records observations that can be compared with the predicted curve. NOAA's [Tides and Currents portal](https://tidesandcurrents.noaa.gov/) presents real-time measurements where instruments are available. Preliminary observations can contain gaps and later undergo quality control.

Argo's [coastal water-level page](https://www.argo.net/tides-and-coastal-water-levels-today/) brings prediction and current-condition context together. A tide table downloaded months earlier cannot account for an approaching storm, so weather information belongs in any safety decision.

## Tide products do not predict tidal currents

A rising tide often accompanies flood current and a falling tide often accompanies ebb, but local timing can be offset. Slack water may occur well before or after high tide. The relationship depends on whether the tidal wave behaves more like a standing wave or a progressive wave in that waterway.

Current predictions list speed, direction and reversal phases for designated current stations. Boaters entering a narrow pass or divers planning a slack-water window should use that product rather than infer flow from a tide curve.

The practical choice is straightforward. Use a table for exact predicted highs and lows and use a chart to visualize the changing water level between them. In both cases, confirm the station, datum, units and time zone before applying the information.

## Common tide-reading mistakes

One frequent mistake is reading tomorrow's column after midnight without noticing that the date has changed. Another is treating a negative **tide height** as a depth below the seafloor. The negative value only places the prediction below the selected vertical datum.

Users also confuse water depth with tide height. Estimated depth equals the charted depth adjusted for the predicted tide, subject to local conditions and the compatibility of the two datums. Shoaling, dredging and survey age introduce additional uncertainty.

A third mistake is assuming the steepest part of a tide curve gives the strongest current. Water-height change and horizontal velocity are related differently in each basin. A current station is needed when flow speed determines safety.

Finally, screenshots become stale. Astronomical predictions remain stable, but observation overlays and weather forecasts update frequently. Saving the station identifier is more reliable than saving an unlabeled image that no longer shows its date or reference information.

## Choosing the format for a real task

Argo's [ocean conditions page](https://www.argo.net/ocean-conditions-today/) can complement a tide product with broader environmental context. Tide height remains only one part of coastal conditions, particularly where swell or wind creates hazardous water despite a favorable predicted level.

Small craft also need to distinguish under-keel clearance from bridge clearance. More water improves depth over a shoal but reduces space beneath a fixed bridge. Each calculation uses the relevant charted reference and the vessel's actual dimensions.

Tide tables printed for an entire year remain valuable where connectivity is poor. Users should confirm that official corrections have not changed the station. Digital tools add convenience, yet the underlying responsibility to check labels and datums is unchanged.

A chart's visual curve is especially helpful for teaching because it shows that high and low tides are turning points within continuous motion. The table complements it with precise entries. Together they explain more than either format alone.

The two formats are therefore complementary views of one prediction, provided their station and reference information match.