EC3A: 6.5 m clear of the highest tide in the London Bridge ledgers

The lowest postcode in EC3A, EC3A 8AQ, stands 6.5 m above the highest tide in the London Bridge ledgers (5.41 m, 1 February 1953). The highest, EC3A 3AA, stands 12 m above it.
- Ground at eight in ten of its postcodes: between 14 m and 16 m, measured from Ordnance Datum; the middle one stands at 15 m.
- None lies in the Environment Agency's Flood Zone 3 from the sea.
- Mostly in City of London; partly in Islington.