1. Why construction costs vary geographically
A site does not cost the same in Bordeaux, Paris and Fort-de-France, even for an identical programme with the same drawings and the same materials. The geographic differences have several structural origins.
- Labour cost, directly tied to the local cost of living. A mason in Paris must house, feed and transport themselves in a city where everything costs more; those living costs feed into their wage expectations and therefore into contractors' prices.
- Pressure on the contractor market. In the Paris region and the major cities, construction firms' order books are structurally fuller than in rural areas. A contractor who does not need your project to fill its programme will not price it aggressively.
- Logistical constraints. Delivering materials into inner Paris costs more than on the periphery: delivery windows, urban convoys, low-emission zones, the cost of parking lorries. Those costs reappear in the tenders.
- Climatic and seismic requirements. Seismic zones, the Alps, the Caribbean, and cyclone zones in the overseas territories require strengthened structures. Mountain areas impose greater snow and wind loads. These regulatory premiums add to the base regional factor.
2. The reference factors
The table gives the reference factors for the principal French areas. A factor of 1.00 corresponds to standard provincial conditions, the larger provincial cities outside the tightest markets. Every ratio published by Quostra is expressed on that base.
| Area | Factor | Representative cities or territories | Principal drivers |
|---|---|---|---|
| Remote rural | 0.88 – 0.93 | Sparsely populated inland departments, towns under 10,000 | Cheaper local labour, cheaper materials in some cases, strong competition between contractors |
| Standard provincial | 1.00 | The reference: Bordeaux, Nantes, Rennes, Strasbourg, Toulouse | The benchmark on which every pillar ratio is expressed |
| Regional cities | 1.05 – 1.12 | Lyon, Marseille, Lille, Nice, Montpellier, Grenoble | Market pressure, cost of living, indirect land effects, urban constraints |
| Outer Paris region | 1.15 – 1.22 | The outer departments of the Paris region | Cost of housing workers, material transport, competition for skilled labour |
| Inner Paris region | 1.25 – 1.38 | Paris and the inner suburbs | Logistical constraints, night working, difficult access, contractor pricing in a tight market |
| Mediterranean coast | 1.15 – 1.25 | Nice, Cannes, Antibes | Seasonality, recruitment difficulty, a very tight market in high season |
| Alps and mountain areas | 1.10 – 1.20 | Chamonix, Megève, Courchevel, above 1,000 m | Difficult access, seasonal working, extra provision against snow and wind, material haulage |
| Corsica | 1.20 – 1.35 | Ajaccio, Bastia, Porto-Vecchio | Insularity, sea freight for materials, a limited island workforce |
| Caribbean territories | 1.40 – 1.60 | Martinique, Guadeloupe, Saint-Martin | Sea freight, seismic and cyclone standards, partly imported labour |
| Indian Ocean territories | 1.35 – 1.55 | Réunion, Mayotte | Remoteness, seismic standards, a narrow contractor market, imported materials |
How to read the table
To obtain the ratio applicable to your area, multiply the standard provincial ratio by your area's factor.
For example: standard provincial apartments at 2,000 €/m² of floor area. In inner Paris, factor 1.30: 2,000 × 1.30 = 2,600 €/m². In Martinique, factor 1.50: 2,000 × 1.50 = 3,000 €/m².
These factors are market averages over a recent period. They reflect general market conditions, not the specifics of a particular site such as difficult ground or an atypical brief.
3. Practical application: the same programme in six areas
To illustrate the effect concretely, here is the same reference programme, standard apartments, 50 dwellings, 3,500 m² of floor area, provincial base ratio 2,000 €/m².
| Area | Factor | Ratio applied | Works budget excl. VAT, 3,500 m² | Difference against provincial |
|---|---|---|---|---|
| Rural | 0.90 | 1,800 €/m² | 6,300,000 € | − 700,000 € |
| Standard provincial | 1.00 | 2,000 €/m² | 7,000,000 € | The reference |
| Regional city | 1.08 | 2,160 €/m² | 7,560,000 € | + 560,000 € |
| Outer Paris region | 1.18 | 2,360 €/m² | 8,260,000 € | + 1,260,000 € |
| Inner Paris | 1.32 | 2,640 €/m² | 9,240,000 € | + 2,240,000 € |
| Martinique | 1.50 | 3,000 €/m² | 10,500,000 € | + 3,500,000 € |
The gap between a rural area and inner Paris reaches 2,940,000 € on this reference programme, that is 47 % above standard provincial. On a Martinique programme the gap exceeds 3,500,000 €. Those figures illustrate why applying the right regional factor is a non-negotiable step in any estimate.
4. What the factor does not cover
The regional factor is a general correction; it does not replace close analysis of a project's specifics. Several premiums must be handled separately.
| Parameter | Covered by the regional factor? | Explanation |
|---|---|---|
| Local labour | Yes | The local contractor market reflects regional living costs |
| Standard materials such as concrete and steel | Yes | Regional market prices are built into local contractors' tenders |
| Urban logistical constraints | Partly | Built in for inner Paris; check case by case on atypical sites |
| Seismic requirements in the higher zones | No | A distinct structural premium of 5 to 15 % according to zone, to be added separately |
| Cyclone requirements overseas | No | Partly built into the overseas factor, but variable |
| Site slope above 10 % | No | Earthworks and retaining to be priced specifically |
| Difficult ground such as made ground or clay | No | Special foundations; a ground survey is indispensable |
| Speciality materials such as cross-laminated timber or local brick | No | Specific material prices to be sourced locally |
| Current sector inflation | No | The factors are historic averages; in a period of strong inflation the price revision clauses apply |
Seismic zones: a distinct structural premium
Mainland France is divided into five seismic zones, from very low to strong. The upper zones, the Alps, the Pyrenees, the Caribbean, impose seismic design rules that generate a structural premium of 5 to 20 % according to zone and building type.
That premium is distinct from the general regional factor and adds to it. A building in a high seismic zone in the Alps carries both the mountain factor of 1.15 and the seismic premium of 8 to 12 %, giving a corrected ratio of 1.24 to 1.29 times the standard provincial price.
5. How the factors move over time
Convergence after the 2020–2022 crisis
The materials crisis of 2021–2022 temporarily narrowed the geographic gaps: material inflation in steel, timber and insulation hit the whole country uniformly, while labour inflation was more marked in the tight markets. Since 2023 the gaps have been returning to their historic levels.
Durable pressure in the Paris region
The Paris region maintains structurally high factors for two durable reasons: the Grand Paris Express, with 300 simultaneous sites mobilising a substantial share of the regional construction workforce through to 2030, and the chronic housing deficit that sustains a high flow of orders. Neither should reverse in the short term.
Rising pressure in the regional cities
Lyon, Bordeaux, Nantes and Toulouse have seen their factors rise by 0.03 to 0.05 points between 2018 and 2024, under strong demographic growth and sustained economic attractiveness. Economists who worked with factors of 1.03 to 1.05 for these cities should revise them to 1.07 to 1.12.
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In summary
Regional factors range from 0.88 in remote rural areas to 1.60 in the overseas territories. The standard provincial reference of 1.00 corresponds to the larger provincial cities outside the tightest markets. On a 3,500 m² programme, the gap between rural and inner Paris exceeds 2.9 M€, that is 47 % of the budget. The factor covers labour, standard materials and general logistical constraints, but not seismic premiums, difficult ground or speciality materials, which are analysed separately. In the Paris region and overseas, the combination of the general factor and the specific regulatory premiums can take the corrected ratio to 1.30 to 1.70 times the standard provincial price.
Reference basis of the figures
These bands are orders of magnitude for framing, and their reference market is the Paris region. They serve to place a budget at the earliest stages and to compare building types with one another. They replace neither a tender exercise nor an estimate prepared on drawings, and they are not a record of prices actually charged.
The ratios per square metre and per item on this page are stated in January 2026 values. They were updated from January 2025 values, the basis adopted for the whole cocoon, using the BT01 all-trades index published monthly by INSEE on its 2010 base: 132.0 in January 2025, 134.7 in January 2026, a rise of about 2 %.
The global amounts quoted as examples, and any rents, charges or receipts expressed per year or per night, remain on their own basis: a building cost index does not apply to them.
To bring the ratios forward, apply the usual revision formula: updated value = page value × (BT01 for the month in question / 134.7). The index has kept rising since: it stood at 138,3 in June 2026, the last value published when this page was checked, that is 2,7 % above the reference base. BT01 measures contractors' input costs, wages and social charges, materials, plant and energy, not the prices actually tendered.
Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.