The number exists. You should have it first.
Approximate duration · 10 min
An indicative budget range for your property. Not a binding quote.
Twelve-section calculator that returns an indicative cost range for residential renovation projects in London. Inputs cover property type and age, listed status, London zone, floor area, scope of works, fabric, electrical and plumbing, mechanical, kitchen, bathrooms and furniture, finishes, structural, and external works and programme. Floor area accepts 25m² to 1,000m². Output is an indicative low, mid, and high £-range, exclusive of VAT. The range is indicative only, not a quote, not an offer, not a contract.
The calculator covers:
Mayfair runs 20–40% higher than Marylebone on a comparable scope.
Basement, listed building, and estate consent each add a layer the headline rate doesn't show.
BOROUGH BREAKDOWN →Yes. The renovation cost calculator is at myrmexgroup.co.uk/how-much. It runs in twelve sections covering property, scope, specification tier, and structural work. Most users complete it in around ten minutes. Output is an indicative cost range with low, mid, and high figures in pounds, exclusive of VAT. The number is indicative, not a quote.
Q.01The calculator estimates the construction cost range based on property type, age, scope of works, specification tier, and structural complexity. It excludes VAT. It excludes professional fees paid outside Myrmex, including architect, structural engineer, and planning consultant. It excludes client-side furniture and FF&E. Statutory fees beyond what the calculator flags are also excluded.
Q.02No. The calculator returns an indicative range, not a binding figure. The binding number is the cost plan locked at the Pre-Construction Services Agreement (PCSA) stage. The PCSA is a paid four-week pre-construction process where every line item is priced and signed before the main construction contract is entered.
Q.03Residential properties between 25m² and 1,000m². Above 600m², the calculator advises contacting Myrmex directly. Property types: period house, period flat, new-build house, new-build flat. Listed buildings supported, including Grade II, Grade II*, and Grade I. Location input is by London Underground zone: Zone 1, Zone 2, Zone 3, or Zone 4 to 6. The calculator scope is wider than the Myrmex service area by design.
Q.04The calculator is a pre-engagement indicator. It runs on twelve panels of structured input and returns a low, mid, and high range. The PCSA is a paid four-week process where every line item is priced and signed before the main construction contract. The cost plan locked at the end of the PCSA is the binding number. The calculator narrows the gap between indicative and binding; it does not close it.
Q.05Two options. The first is the full email breakdown: enter first name and email, and the calculator sends every line item, the programme timeline, and procurement flags to your inbox. A reference number is issued (format MG-XXXXXX). The second is a fifteen-minute call via Calendly. Neither carries an obligation. The calculator does not require an email to return the indicative range; the breakdown is opt-in.
Q.06The construction cost is calculable. An indicative range can be modelled from GIA, scope, and specification tier. The number is rarely published before engagement. The client receives it after entering the conversation, not before. Myrmex previously ran a different company for two years and did not publish a calculator. The calculator does not know the building; the PCSA is where the building gets known. Publishing it changes the timing: the client arrives with a number rather than waiting for one.
Q.07If the number works, the next move is a conversation.
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