Why Tide Times and Heights Differ Between Websites

Different tide sites can agree on the shape of the tide but still show different-looking numbers.

The height zero is different

The largest difference is usually height. Tide Checking shows gauge levels in metres above Ordnance Datum, or mAOD. Many tide tables use chart datum. Those two zero levels are not the same, so a low water shown as -0.6 mAOD here can appear as a positive tide-table height elsewhere.

The times can differ by a few minutes

A few minutes of difference is normal between independent predictions, official tables and observed gauge-based fits. Tide Checking fits harmonic constituents from Environment Agency observations; other services may use a different model, smoothing method, or reference port.

Use the live gauge check

Each station page compares the latest gauge reading with the prediction for the same minute. That difference is mostly weather surge, and it is the best quick check of how closely the astronomical prediction matches the water on the day.