House prices in 'AL5 1', Harpenden

This article reveals price per square foot data and various charts to help you understand current housing market in 'AL5 1' (Harpenden) - statistics were last calculated on 16 October 2024.

Defining 'AL5 1'

This analysis is limited to properties whose postcode starts with "AL5 1", this is also called the postcode sector. There are no official postcode sector names so I've just labelled it AL5 1, Harpenden. It is shown in red on the map below.

Want to change geography?

You can click on the map above to change to a neighbouring sector, or you can use the search form below.

Price per square foot

Knowing the average house price in AL5 1 is not much use. However, knowing average price per square foot can be quite useful. Price per sqft allows some comparison between properties of different size. We define price per square foot as the sold price divided by the internal area of a property:

£ per sqft = price ÷ internal area

For example in July 2024, 34, Ranleigh Walk, Harpenden, AL5 1SR sold for £690,000. Given the internal area of 1,022 square feet recorded on the EPC, the price per sqft is £690,000 ÷ 1,022 sqft = £674.

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 AL5 1 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 sqft for 'AL5 1' vs 'AL5'

The chart above is called a histogram, it helps you see the distribution of house price per sqft in AL5 1 To make this chart we put all the sales data into a series of £ per sqft 'buckets' (e.g. £715 to £743, £743 to £771, £771 to £798 etc...) we then count the number of sales with within in each bucket and plot the results. The histogram is based on 178 sales that took place in AL5 1, Harpenden 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 AL5 1, Harpenden. Notably, only 25% of properties that sold recently were valued at more than £713 sqft. For anything to be valued more than this means it has to be more desireable than the clear majority of AL5 1 homes.

Box plot of £ per sqft for AL5 1

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 foot property price distributions, box plots represent the variation in property prices within a geographic area e.g. Harpenden. The chart above shows a boxplot for 'AL5 1' as well as the 'AL5' postcode district.

  • 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 foot in 'AL5 1' is £638.
  • 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 178 transactions in AL5 1, Harpenden half were sold for between £565 and £713 per square foot.
  • 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; 178 for AL5 1, Harpenden.

    • Property price map for Harpenden

    Have a look at the interactive price map I created for myself. Use it to explore 'AL5 1' house prices all the way down to individual property plots.

    Property price heatmap for Harpenden
    House price map for Harpenden

    Harpenden house price forecasting

    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 AL5 1 (Harpenden) compared with the wider postcode district of AL5. You can extrapolate from this based on your own views on future interest rates, inflation and other factors.

    House price index for AL5 1

    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 'AL5 1' property prices over the last 20 years. The index is calculated from the average price paid per sqft for property in AL5 1 and is set to 100 in 2004. I'm comparing the trends for AL5 1,Harpenden with the wider postcode district of AL5 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 St Albans 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 AL5 1
    AL5 1 sector AL5 district
    Nominal Real Nominal Real
    20 yr per annum 4.4% 1.7% 4.2% 1.5%
    20 yr total 138.8% 41.5% 126.2% 34.0%
    10 yr per annum 3.3% 0.5% 2.7% -0.1%
    10 yr total 37.9% 4.7% 30.1% -1.2%
    5 yr per annum 3.1% -1.0% 2.5% -1.6%
    5 yr total 16.2% -4.9% 12.9% -7.6%
    1 yr per annum -0.2% -4.2% -2.4% -6.3%
    1 yr total -0.2% -4.2% -2.4% -6.3%

    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, AL5 1 sector have seen a 1.7% annual change when adjusted for inflation. This translates to a total change of 41.5% in real terms.
    • Over the past 5 years, AL5 1 sector have seen a -1.0% annual change when adjusted for inflation. This translates to a total change of -4.9% in real terms.

    Most recent AL5 1 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 £sqft Recent sales
    Piggottshill Lane, Harpenden, AL5 1L 121 sqm £629 22
    Cravells Road, Harpenden, AL5 1B 81 sqm £705 21
    Meadway, Harpenden, AL5 1J 149 sqm £677 18
    Coleswood Road, Harpenden, AL5 1E 104 sqm £566 17
    Southdown Road, Harpenden, AL5 1Q 57 sqm £494 16
    Eastmoor Park, Harpenden, AL5 1B 129 sqm £581 13
    Grove Avenue, Harpenden, AL5 1E 118 sqm £680 11
    Gordons Walk, Harpenden, AL5 1L 92 sqm £687 9

    Search for your street here.

    Nearby geographies

    The table below shows how 'AL5 1' compares to the other postcode sectors in AL5.

    Sector Lower quartile Median Upper quartile Sales in last 2yr
    AL5 5 Harpenden £537 sqft £617 sqft £719 sqft 180
    AL5 4 Harpenden £531 sqft £647 sqft £739 sqft 173
    AL5 3 Harpenden £493 sqft £588 sqft £692 sqft 95
    AL5 2 Harpenden £631 sqft £753 sqft £843 sqft 129
    AL5 1 Harpenden £565 sqft £638 sqft £713 sqft 178
    AL4 9 St Albans £529 sqft £622 sqft £703 sqft 268
    AL4 8 Wheathampstead £508 sqft £566 sqft £634 sqft 126
    AL3 6 St Albans £501 sqft £553 sqft £643 sqft 60

    Raw data

    Our analysis of AL5 1 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 sqft £/sqft
    34, Ranleigh Walk, Harpenden £690,000
    Jul-2024
    		 1,022 674
    39, Churchfield, Harpenden £702,500
    Jul-2024
    		 882 795
    4, Queens Rd, Harpenden £695,000
    Jul-2024
    		 957 725

    See the entire list of all sales in AL5 1 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.