A tide table is only useful if you can trust it at the slipway. This page explains where every number on TideTimes.ie comes from, what has to be true before a nightly update goes live, and how our times compare with an independent official table.
Where the numbers come from
Every time and height is an astronomical tide prediction published by the Marine Institute, the state agency that runs the Irish National Tide Gauge Network. Most predictions come from the Institute’s analysis of years of measurements at its gauges; a few are for points covered by its ocean model. They are published under a CC BY 4.0 licence. We do not change, smooth or estimate them.
What we add, and work out ourselves:
- Conversion to Irish local time, including the switch to and from summer time.
- Grouping into calendar days, the 30-day calendar and the daily range.
- Spring and neap dates, picked from the turning points of that range.
- Sunrise and sunset for each place, from the standard solar equations, accurate to about a minute.
- Daylight windows: one hour either side of each high and low water, cut to sunrise and sunset. Arithmetic on the numbers above, nothing more.
- For beaches and harbours without their own gauge, the nearest gauge on the same coast, named on the page with its distance.
Checks before every update
The site rebuilds every night just after midnight Irish time with the latest predictions. Before anything is published, a set of automatic tests runs. If any test fails, nothing is published, the version from the night before stays live, and we get an alert the same day. The tests check that:
- every gauge on the site has predictions, running at least 60 days ahead;
- times are in order, with no duplicates, and high and low water alternate;
- every height is within the physical range for the Irish coast, and every high is above the low before it;
- UTC times convert to the right Irish day and hour on both sides of the clock change;
- days that have passed drop off the top of every table, and today stays even after its first tide;
- spring and neap detection and the daylight windows give the expected answers on worked examples.
Pages also hide any day that has passed as soon as they load, so a page saved on your phone yesterday never shows yesterday at the top.
Comparison with Dublin Port’s own tables
Dublin Port Company publishes its own tide tables for North Wall, computed independently and measured from chart datum. We set our Dublin Port predictions beside them for 1 and 2 November 2026. To compare heights we add 2.4 m to ours (see the chart datum guide for why).
| Day | Tide | TideTimes.ie | Dublin Port table | Difference |
|---|---|---|---|---|
| Sun 1 Nov | High | 03:55, 1.22 m | 03:47, 3.62 m | +8 min, 0 cm |
| Sun 1 Nov | Low | 09:20, -1.01 m | 09:24, 1.43 m | -4 min, -4 cm |
| Sun 1 Nov | High | 16:20, 1.40 m | 16:10, 3.78 m | +10 min, +2 cm |
| Sun 1 Nov | Low | 22:15, -1.34 m | 22:14, 1.09 m | +1 min, -3 cm |
| Mon 2 Nov | High | 05:15, 1.10 m | 05:08, 3.49 m | +7 min, +1 cm |
| Mon 2 Nov | Low | 10:40, -0.84 m | 10:40, 1.58 m | 0 min, -2 cm |
| Mon 2 Nov | High | 17:35, 1.37 m | 17:27, 3.72 m | +8 min, +5 cm |
| Mon 2 Nov | Low | 23:40, -1.33 m | 23:31, 1.13 m | +9 min, -6 cm |
Times agree within 10 minutes and heights within 6 cm. Our times run a few minutes later, which fits the Marine Institute gauge and North Wall being at different spots in the port. Both are good predictions of the same tide. Neither knows about the weather, which on a stormy day moves the real level far more than this.
What we do not do
- We do not forecast storm surge. Tide predictions in Ireland, from any source, leave it out.
- We are not a navigation service. For navigation use current Admiralty or Irish charts and official notices.
- We do not say a beach or a crossing is safe. Windows on our pages are planning aids. Lifeguards, the Coast Guard and local signs come first.
Safety and guide content
Safety advice on the site follows Water Safety Ireland, the RNLI and the Irish Coast Guard. Guides cite the public pages they rely on and show the date they were last checked. Fishing rules come from Inland Fisheries Ireland and the Irish Statute Book.
Found a mistake?
Email hello@tidetimes.ie with the page and what looks wrong. If a local time difference for a beach is off, tell us what you see on the ground; local knowledge is the best check there is. See contact.
Change log
- 25 October 2026. Six new guides: reading a tide table, chart datum and OD Malin, sea swimming, tidal walks and cut-off, shore fishing, and why the tide at a beach differs from the port. Every beach and gauge page now has a “Best times this week” table with the daylight windows around high and low water, and flags the week’s spring or neap tide. Open
- 25 October 2026. Dublin predictions compared with Dublin Port Company’s 2026 tables: times within 1 to 10 minutes, heights within a few centimetres after the datum is converted. Method and results on How we check. Open
- 5 October 2026. The nightly update now tries again when it fails at the first attempt. On 4 and 5 October it had stopped early and the pages kept the previous night’s version.
- 22 September 2026. New spring and neap tide page with the next dates for Ireland, worked out from the Dublin Port predictions. Pages now rebuild just after Irish midnight so “today” is always today. Open
- 5 September 2026. 106 beach and harbour pages added, each linked to its nearest gauge, with a 30-day calendar, sunrise and sunset, and local safety notes. Open
- 28 August 2026. County pages added, with every gauge in the county side by side. Open
- 21 August 2026. TideTimes.ie launched with tide times for the Marine Institute gauges around the Irish coast.