House prices in SG15 (Arlesey)

This article shows price per square metre data and various charts to help you understand the housing market in SG15 - stats were last calculated on 01 November 2024.

Defining 'SG15'

This analysis is limited to properties whose postcode starts with "SG15", this is also called the postcode district. There are no official postcode district names so I've just labelled it SG15, Arlesey. It is shown in red on the map below.

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Price per square metre

Knowing the average house price in SG15 is not much use. However, knowing average price per square metre can be quite useful. Price per sqm allows some comparison between properties of different size. We define price per square metre as the sold price divided by the internal area of a property:

£ per sqm = price ÷ internal area

For example in September 2024, 2, Wesley Close, Arlesey, SG15 6SQ sold for £185,000. Given the internal area of 47 square metres recorded on the EPC, the price per sqm is £185,000 ÷ 47 sqm = £3,936.

England & Wales have been officially metric since 1965. However house price per square foot is prefered by some estate agents and those of sufficiently advanced age ;-). It is a huge pain to code the automatic conversion for square meters to square feet for all the graphs and charts on SG15 and elsewhere. All the conditionals turn my tidy code for into spaghetti. I will get around to it at some point, but for now you can just divide everything by 10 in your head, move a decimal place and you'll be close enough. If you want to be more precise 1 sqm = 10.76391 sqft.

Distribution of £ per sqm for houses vs flats in SG15

The chart above is called a histogram, it helps you see the distribution of house price per sqm in SG15 To make this chart we put all the sales data into a series of £ per sqm 'buckets' (e.g. £3,350 to £3,500, £3,500 to £3,650, £3,650 to £3,800 etc...) we then count the number of sales with within in each bucket and plot the results. The histogram is based on 124 sales that took place in SG15, in the last 24 months.

Generate a custom histogram like the one above but based on your own criteria.

You can see the spread of prices above. This is because although internal area is a key factor in determining valuation, it is not the only factor. Many factors other than size affect desirability; these factors could be condition, aspect, garden size, negotiating power of the vendor etc.

The spread of prices will give you a feel of the typical range to expect in SG15, Arlesey. Notably, only 25% of properties that sold recently were valued at more than £4,550 sqm. For anything to be valued more than this means it has to be more desireable than the clear majority of SG15 homes.

Box plot of £ per sqm for SG15

Tip: click on the chart to see the values.

The chart above is called a boxplot (or a box-and-whisker plot). Box plots, like histograms, are used to graphically represent the distribution of data, showing the central tendency, spread of the distribution. In the context of £ per square metre property price distributions, box plots represent the variation in property prices within a geographic area e.g. Arlesey. The chart above shows a boxplot for 'SG15' as well as the 'SG' postcode area.

  • Median: The horizontal line inside the box represents the median (£ per square meter). This is the midpoint of the data, meaning 50% of the prices are below this value, and 50% are above. The middle price per square metre in 'SG15' is £4,140.
  • Interquartile Range (IQR): The box spans from the 25th percentile (Q1) to the 75th percentile (Q3). This is the range where the middle 50% of the data lies, giving a good indication of the typical price spread. Of the 124 transactions in SG15, Arlesey half were sold for between £3,610 and £4,550 per square metre.
  • Whiskers: In our case, the whiskers extend from the 9th percentile (at the lower end) to the 91st percentile (at the upper end), This provides a slightly broader view of the distribution by including the middle 82% of records. The whiskers capture most of the variation but exclude extreme outliers caused by data errors in recording sold house prices or internal area.
  • 'n=' is the number of property transactions the box plot is based on; 124 for SG15, Arlesey.

    • Property price map for Arlesey

    Have a look at the interactive price map I created for myself. Use it to explore 'SG15' house prices all the way down to individual property plots.

    Property price heatmap for Arlesey
    House price map for Arlesey

    Will SG15 house prices drop in 2025?

    I cannot tell what house prices will do in the future and don't believe anyone who says they can. However we can plot price trends, I have done this in the chart below for SG15 (Arlesey) compared with the wider postcode area 'SG'. You can extrapolate from this based on your own views on future interest rates, inflation and other factors.

    House price index for SG15

    Tip: click on the legend items to show/hide different lines

    Download house price index as CSV (premium users only).

    The chart above shows changes in 'SG15' property prices over the last 20 years. The index is calculated from the average price paid per sqm for property in SG15 and is set to 100 in 2004. The chart compares trends for SG15, Arlesey against those of the broader postcode area 'SG'. What is more interesting is to look at the difference between flats and houses, even those in the same area follow a very different trend, to get a robust enough sample size to see this we need to zoom out and look at house price trends for the entire Central Bedfordshire local authority.

    The dashed lines show nominal house price changes, the solid lines show the same data adjusted for inflation. Economists call this the 'real' price change. You have to take inflation into account when comparing prices over time. It's calculated using the formula:

    Real Rate of Return = (1 + Nominal Rate) ÷ (1 + Inflation Rate) – 1
    In this formula, the nominal rate is the rate of change before any adjustments, and the inflation rate is taken from the Consumer Price Index. The real rate of return is a more accurate measure of change in value, because £1 today does not have the same buying power as £1 in the past. For example, if a savings account pays an interest rate of 3% per year and the inflation rate is 5% per year, the real rate of return is -2%. This means that the investment's value is shrinking by 2% each year.

    Historic returns for SG15
    SG area SG15 district
    Nominal Real Nominal Real
    20 yr per annum 3.4% 0.7% 3.4% 0.7%
    20 yr total 95.4% 15.7% 95.2% 15.6%
    10 yr per annum 4.0% 1.2% 4.8% 1.9%
    10 yr total 48.2% 12.5% 59.5% 21.1%
    5 yr per annum 2.6% -1.4% 3.7% -0.3%
    5 yr total 13.8% -6.9% 20.1% -1.7%
    1 yr per annum -0.3% -4.3% 5.0% 0.8%
    1 yr total -0.3% -4.3% 5.0% 0.8%

    This table complements the house price index chart above, presenting the data in a more detailed format. It breaks down the information into 20-year, 10-year, 5-year, and 1-year periods, further categorized by property type. For each period, we display both a per annum rate of change and a total rate of change.

    The total rate of change represents the overall change over the entire period. The formula for total return is:

    Total return = (Index at end of period ÷ Index at start of period) - 1

    The per annum rate of change is the annualized rate of change over the period. This is equivalent to the annual bank savings rate you would need to achieve the same total return over the given period. This annualized return is also known as the Compound Annual Growth Rate (CAGR). The formula for CAGR is:

    CAGR = (1 + Total return) ^ (1 ÷ Number of years) - 1

    Some specific examples:

    • Over the past 20 years, SG area have seen a 0.7% annual change when adjusted for inflation. This translates to a total change of 15.7% in real terms.
    • Over the past 5 years, SG area have seen a -1.4% annual change when adjusted for inflation. This translates to a total change of -6.9% in real terms.

    Most recent SG15 sales

    For the most recent sales activity, rather than a summarized average, it is better to see the underlying data. This is shown in the chart below, where blue dots represent individual sales, click on them to see details. If there is an obvious trend you should be able to spot it here amid the noise from outliers.

    Tip: hover over dots to see details

    Street level data

    Street Avg size Avg £sqm Recent sales
    High Street, , SG15 6S 75 sqm £4,255 29
    Ramerick Gardens, , SG15 6X 66 sqm £4,479 17
    Hospital Road, , SG15 6R 61 sqm £4,148 16
    Chase Hill Road, , SG15 6U 78 sqm £4,278 16
    Hitchin Road, , SG15 6R 81 sqm £3,596 13
    House Lane, , SG15 6X 102 sqm £4,037 13
    Hitchin Road, , SG15 6S 85 sqm £3,929 12
    Lamb Meadow, , SG15 6R 50 sqm £4,786 12

    Search for your street here.

    Nearby geographies

    The table below shows how 'SG15' compares to the other postcode districts nearby 'SG15'.

    District Lower quartile Median Upper quartile Sales in last 2yr
    SG9 Buntingford £4,300 sqm £4,830 sqm £5,320 sqm 259
    SG8 Royston £3,790 sqm £4,350 sqm £4,960 sqm 959
    SG7 Baldock £4,040 sqm £4,620 sqm £5,310 sqm 281
    SG6 Letchworth Garden City £3,800 sqm £4,510 sqm £5,250 sqm 656
    SG5 Stotfold £4,020 sqm £4,640 sqm £5,470 sqm 905
    SG4 Hitchin £4,410 sqm £5,150 sqm £5,920 sqm 658
    SG3 Knebworth £4,440 sqm £5,250 sqm £5,770 sqm 138
    SG2 Stevenage £3,690 sqm £4,110 sqm £4,730 sqm 753
    SG19 Sandy £3,350 sqm £3,790 sqm £4,310 sqm 552
    SG18 Biggleswade £3,570 sqm £4,070 sqm £4,650 sqm 807

    Raw data

    Our analysis of SG15 is derived from what is essentially a big table of sold prices from Land Registry with added property size information. Below are three rows from this table to give you an idea.

    Address Paid sqm £/sqm
    2, Wesley Close, £185,000
    Sep-2024
    		 47 3,936
    1, Lynton Avenue, £430,000
    Sep-2024
    		 99 4,343
    6, Chancellors, £460,000
    Aug-2024
    		 171 2,690

    See the entire list of all sales in SG15 here.

    About

    I created HouseMetric because I wanted to see this data and analysis myself, I also wanted to teach myself to build a website. Please give me feedback or spread the word about it. I'm constantly tinkering and adding more stuff to it.