SG3 postcode district: Knebworth and around, Hertfordshire

SG3 is a postcode district in Hertfordshire, with 206 postcodes in use in 1 sector. It has postcodes in Knebworth and Woolmer Green. It is split between 3 councils: North Hertfordshire (119 postcodes), Welwyn Hatfield (49) and East Hertfordshire (38).

Postcodes in use
206
Sectors
1
Councils
3 councils
Places
2 places

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026. See all our data sources

Every postcode in SG3, by flood risk

Map of every postcode in SG3, by flood risk Of the 206 postcodes in SG3 that ONS places, 206 are not on the Environment Agency's at-risk list. 2 postcodes lie beyond the edge and are listed under the map. Places named: Knebworth, Woolmer Green. Drawn over roads, rivers and built-up areas. North is up; the scale bar is 1 km. A1(M)A602 SG3 6AA: not on the flood risk listSG3 6AB: not on the flood risk listSG3 6AD: not on the flood risk listSG3 6AE: not on the flood risk listSG3 6AF: not on the flood risk listSG3 6AG: not on the flood risk listSG3 6AH: not on the flood risk listSG3 6AJ: not on the flood risk listSG3 6AL: not on the flood risk listSG3 6AN: not on the flood risk listSG3 6AP: not on the flood risk listSG3 6AQ: not on the flood risk listSG3 6AR: not on the flood risk listSG3 6AS: not on the flood risk listSG3 6AT: not on the flood risk listSG3 6AU: not on the flood risk listSG3 6AW: not on the flood risk listSG3 6AX: not on the flood risk listSG3 6AY: not on the flood risk listSG3 6AZ: not on the flood risk listSG3 6BA: not on the flood risk listSG3 6BB: not on the flood risk listSG3 6BD: not on the flood risk listSG3 6BE: not on the flood risk listSG3 6BG: not on the flood risk listSG3 6BH: not on the flood risk listSG3 6BJ: not on the flood risk listSG3 6BL: not on the flood risk listSG3 6BN: not on the flood risk listSG3 6BP: not on the flood risk listSG3 6BQ: not on the flood risk listSG3 6BS: not on the flood risk listSG3 6BT: not on the flood risk listSG3 6BU: not on the flood risk listSG3 6BW: not on the flood risk listSG3 6BX: not on the flood risk listSG3 6BY: not on the flood risk listSG3 6DA: not on the flood risk listSG3 6DB: not on the flood risk listSG3 6DD: not on the flood risk listSG3 6DE: not on the flood risk listSG3 6DF: not on the flood risk listSG3 6DG: not on the flood risk listSG3 6DH: not on the flood risk listSG3 6DJ: not on the flood risk listSG3 6DN: not on the flood risk listSG3 6DP: not on the flood risk listSG3 6DQ: not on the flood risk listSG3 6DR: not on the flood risk listSG3 6DS: not on the flood risk listSG3 6DT: not on the flood risk listSG3 6DU: not on the flood risk listSG3 6DX: not on the flood risk listSG3 6DY: not on the flood risk listSG3 6DZ: not on the flood risk listSG3 6EA: not on the flood risk listSG3 6EB: not on the flood risk listSG3 6ED: not on the flood risk listSG3 6EE: not on the flood risk listSG3 6EH: not on the flood risk listSG3 6EL: not on the flood risk listSG3 6EN: not on the flood risk listSG3 6EP: not on the flood risk listSG3 6EQ: not on the flood risk listSG3 6ER: not on the flood risk listSG3 6EU: not on the flood risk listSG3 6EW: not on the flood risk listSG3 6EX: not on the flood risk listSG3 6EY: not on the flood risk listSG3 6FA: not on the flood risk listSG3 6FB: not on the flood risk listSG3 6FD: not on the flood risk listSG3 6FE: not on the flood risk listSG3 6FF: not on the flood risk listSG3 6FG: not on the flood risk listSG3 6FH: not on the flood risk listSG3 6FN: not on the flood risk listSG3 6FP: not on the flood risk listSG3 6FS: not on the flood risk listSG3 6GL: not on the flood risk listSG3 6HB: not on the flood risk listSG3 6HE: not on the flood risk listSG3 6HF: not on the flood risk listSG3 6HG: not on the flood risk listSG3 6HH: not on the flood risk listSG3 6HJ: not on the flood risk listSG3 6HL: not on the flood risk listSG3 6HP: not on the flood risk listSG3 6HS: not on the flood risk listSG3 6HW: not on the flood risk listSG3 6HY: not on the flood risk listSG3 6JD: not on the flood risk listSG3 6JE: not on the flood risk listSG3 6JF: not on the flood risk listSG3 6JG: not on the flood risk listSG3 6JJ: not on the flood risk listSG3 6JL: not on the flood risk listSG3 6JN: not on the flood risk listSG3 6JP: not on the flood risk listSG3 6JS: not on the flood risk listSG3 6JU: not on the flood risk listSG3 6JW: not on the flood risk listSG3 6JX: not on the flood risk listSG3 6JY: not on the flood risk listSG3 6JZ: not on the flood risk listSG3 6LA: not on the flood risk listSG3 6LB: not on the flood risk listSG3 6LD: not on the flood risk listSG3 6LE: not on the flood risk listSG3 6LG: not on the flood risk listSG3 6LJ: not on the flood risk listSG3 6LL: not on the flood risk listSG3 6LN: not on the flood risk listSG3 6LP: not on the flood risk listSG3 6LR: not on the flood risk listSG3 6LS: not on the flood risk listSG3 6LT: not on the flood risk listSG3 6LU: not on the flood risk listSG3 6LW: not on the flood risk listSG3 6LX: not on the flood risk listSG3 6LZ: not on the flood risk listSG3 6NA: not on the flood risk listSG3 6NB: not on the flood risk listSG3 6ND: not on the flood risk listSG3 6NL: not on the flood risk listSG3 6NN: not on the flood risk listSG3 6NP: not on the flood risk listSG3 6NS: not on the flood risk listSG3 6NU: not on the flood risk listSG3 6NX: not on the flood risk listSG3 6PB: not on the flood risk listSG3 6PD: not on the flood risk listSG3 6PE: not on the flood risk listSG3 6PF: not on the flood risk listSG3 6PG: not on the flood risk listSG3 6PH: not on the flood risk listSG3 6PL: not on the flood risk listSG3 6PP: not on the flood risk listSG3 6PR: not on the flood risk listSG3 6PS: not on the flood risk listSG3 6PT: not on the flood risk listSG3 6PU: not on the flood risk listSG3 6PW: not on the flood risk listSG3 6PY: not on the flood risk listSG3 6QA: not on the flood risk listSG3 6QB: not on the flood risk listSG3 6QD: not on the flood risk listSG3 6QE: not on the flood risk listSG3 6QF: not on the flood risk listSG3 6QG: not on the flood risk listSG3 6QH: not on the flood risk listSG3 6QJ: not on the flood risk listSG3 6QL: not on the flood risk listSG3 6QN: not on the flood risk listSG3 6QT: not on the flood risk listSG3 6QX: not on the flood risk listSG3 6QZ: not on the flood risk listSG3 6RA: not on the flood risk listSG3 6RB: not on the flood risk listSG3 6RD: not on the flood risk listSG3 6RE: not on the flood risk listSG3 6RF: not on the flood risk listSG3 6RG: not on the flood risk listSG3 6RH: not on the flood risk listSG3 6RJ: not on the flood risk listSG3 6RL: not on the flood risk listSG3 6RN: not on the flood risk listSG3 6RP: not on the flood risk listSG3 6RR: not on the flood risk listSG3 6RS: not on the flood risk listSG3 6RU: not on the flood risk listSG3 6RX: not on the flood risk listSG3 6RZ: not on the flood risk listSG3 6SA: not on the flood risk listSG3 6SB: not on the flood risk listSG3 6SE: not on the flood risk listSG3 6SG: not on the flood risk listSG3 6SL: not on the flood risk listSG3 6SP: not on the flood risk listSG3 6SR: not on the flood risk listSG3 6SS: not on the flood risk listSG3 6ST: not on the flood risk listSG3 6SU: not on the flood risk listSG3 6SX: not on the flood risk listSG3 6SZ: not on the flood risk listSG3 6TA: not on the flood risk listSG3 6TB: not on the flood risk listSG3 6TD: not on the flood risk listSG3 6TE: not on the flood risk listSG3 6TF: not on the flood risk listSG3 6TG: not on the flood risk listSG3 6TL: not on the flood risk listSG3 6TN: not on the flood risk listSG3 6TP: not on the flood risk listSG3 6TQ: not on the flood risk list KnebworthWoolmer Green Map of every postcode in SG3, by flood risk Of the 206 postcodes in SG3 that ONS places, 206 are not on the Environment Agency's at-risk list. 2 postcodes lie beyond the edge and are listed under the map. Places named: Knebworth, Woolmer Green. Drawn over roads, rivers and built-up areas. North is up; the scale bar is 1 km. A1(M) KnebworthWoolmer Green
  • A home or business at high risk: 0
  • At medium risk at worst: 0
  • At low risk at worst: 0
  • At very low risk only: 0
  • Not on the at-risk list: 206

Of the 206 postcodes in SG3 that ONS places, 206 are not on the Environment Agency's at-risk list.

Each mark is a postcode's centre point as ONS gives it, not a building. Press one to see its postcode and open its page. No boundary is drawn. Where marks overlap, the one first in the key is drawn; the counts include every postcode.

The middle of its postcodes: latitude 51.8603, longitude -0.1825. Open this area on OpenStreetMap

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026, the centre point of each postcode; flood risk: Environment Agency, published 6 July 2026; roads, rivers and built-up areas: Contains OS data © Crown copyright and database right 2026. Drawn by us. Street map: Ordnance Survey, OS Open Zoomstack, Open Government Licence v3.0, drawn with MapLibre. How we use them

2 further out, not drawn

These postcodes lie well apart from the rest, so the map is drawn without them to show the rest closer; they are in every count.

SG3 6FRSG3 6PX

What broadband can you get in SG3?

Ofcom reports on 203 of the 206 postcodes in SG3. At 142 of them every home and business can get gigabit broadband.

Postcodes where every home can get gigabit142 of 203
Postcodes where every home can get superfast190 of 203

Ofcom gives each postcode's share of homes and businesses, not how many there are, so these count postcodes. Each postcode page has its own figures. A provider's checker answers for one address.

Check one address on Ofcom's checker

Source: Ofcom, Connected Nations, Spring 2026, data for January 2026, Open Government Licence v3.0. How we use it

Is SG3 at risk of flooding?

None of the 206 postcodes in SG3 is on the Environment Agency's list of postcodes with a home or business in an area at risk of flooding from rivers or the sea.

Homes and businesses in an area at risk of flooding from rivers or the sea, as the Environment Agency counts them, added up over the postcodes. It is for the land, not each building, and leaves out surface water, groundwater and sewers. Each postcode page has its own figures and its flood warning areas.

Source: Environment Agency, Risk of Flooding from Rivers and Sea (postcodes in areas at risk), published 6 July 2026, Open Government Licence v3.0. How we use it

What do homes sell for in SG3?

Homes in SG3 sold for a typical £452,000 in the 12 months to August 2026, across 95 sales, down 6.8% on the 12 months before, HM Land Registry's figures show.

£452,000 typical price, the 12 months to August 2026
12 months to August 2025
£485,000
12 months to August 2026
£452,000

▼ down 6.8% on the 12 months before

Detached£750,000 19 sales
Semi-detached£507,500 24 sales
Terraced£400,000 30 sales
Flat or maisonette£263,500 22 sales

Standard sales of homes at market value. A typical price is the median, the middle sale. Sales take weeks to be registered, so the last month or two are incomplete. Each postcode page gives the figure for its own postcode sector.

Source: HM Land Registry Price Paid Data, files dated 28 September 2026. Contains HM Land Registry data © Crown copyright and database right 2021. This data is licensed under the Open Government Licence v3.0. How we use it

Postcodes in SG3

Pick a sector, then a postcode. A sector is the district plus the next digit.

SG3 6206 postcodes
UK postcode format explained

Places in SG3

Towns and villages with postcodes in SG3, and how many each has here.

Knebworth postcodes,98Woolmer Green postcodes,48

Who covers SG3

How many of the district's postcodes in use fall under each council, constituency and police force area.

Councils

What council am I in?

Constituencies

  • Stevenage156
  • Welwyn Hatfield49
  • North East Hertfordshire1

Police force areas

  • Hertfordshire206

Next to SG3

SG2 postcode district SG4 postcode district All SG districts Knebworth postcodes

"Next to" is by number: the districts before and after SG3 in the SG area.

Check a postcode

Something wrong on this page? Report an error and we will check it against the source.