“How much does a 9×4 Gym Box cost?” — that’s the question Google rarely answers properly. Most websites only list the catalogue 8×3 and 9×3 models. Yet the majority of our clients order bespoke dimensions that don’t appear on any standard spec sheet.
Below is pricing based on real 2026 enquiries from Poland, priced with our current UK price list — not figures spat out by a calculator.
Prices are in GBP, ex-VAT, for the unit built in our Polish factory and installed on your UK site. Delivery is quoted separately by postcode (typically around £1,200–2,500 across the UK, with a quote within 1 business day). The 20% standard VAT rate applies on top for most private buyers; if you’re buying through a limited company, ask your accountant about reclaiming it.
Why do clients choose bespoke dimensions?
Three reasons:
➜ The usable space in the garden is irregular — there’s no room for 11 m of length, but there is for 7×5
➜ The function needs a different proportion — a gym with a shower and WC needs more width than depth
➜ Budget vs. floor area — 7×5 = 35 m² costs differently to a long, narrow layout of similar area
How we price a custom Gym Box
The cost of the module depends on:
➜ Total floor area — the baseline for material cost
➜ Wall perimeter — mineral wool, cladding, flashing
➜ Number and type of openings — every window and door is a separate component
➜ Module height — 2,700 mm as standard; taller costs more
➜ Finish level — Basic, Standard, Premium
A module wider than 3 m (say 5 m) needs a different structural design to a narrow container — and that feeds into the price. The build itself (steel frame, 80–100 mm sandwich panel, U-values) is identical to our catalogue units; only the geometry changes.
Bespoke dimension pricing (GBP, ex-VAT, 2026)
Models up to 30 m²
| Size | Floor area | Module only (no equipment) | With Standard equipment |
|---|---|---|---|
| 6×4 m | 24 m² | from £28,800 | from £39,200 |
| 6×5 m | 30 m² | from £36,000 | from £47,000 |
| 7×4 m | 28 m² | from £33,600 | from £44,800 |
Models 30–45 m²
| Size | Floor area | Module only (no equipment) | With Standard equipment |
|---|---|---|---|
| 7×5 m | 35 m² | from £42,000 | from £53,700 |
| 8×4 m | 32 m² | from £38,000 | from £49,700 |
| 8×3.5 m | 28 m² | from £33,600 | from £44,000 |
| 9×4 m | 36 m² | from £43,200 | from £54,900 |
| 9×5 m | 45 m² | from £54,000 | from £68,300 |
Models 40 m²+
| Size | Floor area | Module only (no equipment) | With Standard equipment |
|---|---|---|---|
| 10×4 m | 40 m² | from £48,000 | from £61,000 |
| 10×5 m | 50 m² | from £60,000 | from £75,600 |
| 12×4 m | 48 m² | from £58,000 | from £73,600 |
| 12×5 m | 60 m² | from £72,000 | from £90,200 |
Indicative prices. The final quote follows once you confirm dimensions, finish level and specification. Installation on your UK site is included; delivery is quoted separately by postcode, and the foundation (a simple ground screw or slab base) is priced per site.
What pushes the price above the table?
The figures above are the lower end for a standard specification. Your project will cost more if you add:
| Option | Effect on price |
|---|---|
| Shower + WC fit-out | +£6,000–16,000 |
| Folding / sliding glass wall | +£4,000–10,000 |
| Slatted cladding (WPC or aluminium) | +£2,000–7,200 |
| Finnish sauna inside the module | +£8,000–16,000 |
| Wet underfloor heating | +£4,800–8,000 |
| Premium equipment (commercial machines) | +£5,200–13,000 |
| Extra ceiling height (> 3 m) | +£4,000–8,000 |
Real examples from 2026 enquiries in Poland
The projects below are real 2026 enquiries from Poland; the amounts are priced with our current UK price list.
Gym Box 7×5 m — private garden gym in Bielsko-Biała (Poland), recreation + training
Slatted cladding, mirrors, HEX LED lighting, air conditioning
→ from £45,200 (complete, excluding foundation and utility connection)
Gym Box 6×5 m — holiday resort in Olchowiec (Poland), guest fitness room
Corner glazing, equipment sized for guests, air conditioning
→ from £50,000–60,000
Gym Box 10×4 m with a combat-sports zone — Teresin (Poland)
Strength area plus a combat corner — heavy bag, mats, 60 kg of dumbbells, two 100 kg weight stacks, slatted cladding
→ from £57,200–60,000
Gym Box 12×4 m with an office corner — Gliwice (Poland)
Module with electrics, no sanitary fit-out, equipment supplied separately
→ from £58,000 (module only)
Unmanned 24/7 community gym, 10×4 m — premium
Slatted facade, QR access system, CCTV, full commercial equipment
→ from £99,600–115,600
How much more do you pay for a bespoke size?
Comparison against the current catalogue models at a similar floor area:
| Catalogue model | Floor area | Price | Comparable bespoke size | Bespoke price |
|---|---|---|---|---|
| 9×3 m Standard | 27 m² | from £32,500 | 6×5 m (30 m²) | from £47,000 |
In practice the premium for going bespoke at a similar area is substantial — on these two specs it is about 45%, because a catalogue package is built in a series while a wider footprint needs its own structural design and a one-off build. Worth it when the function and layout genuinely call for it. If a standard 8×3 or 9×3 footprint fits your garden, the catalogue model is almost always the better-value starting point.
A quick note for UK buyers
Two things worth checking before you commit to a size:
➜ Planning — most garden gyms fall under permitted development, but the rules tighten on outbuildings over a certain footprint, near boundaries, or on listed/conservation sites. Confirm with your local planning authority. We cover this in detail in our garden gym planning permission guide.
➜ Foundation and access — a 10 m or 12 m module needs crane or HIAB access to the site. Tight side returns can rule out the longest sizes, which is another reason a wider, shorter footprint (7×5, 9×5) often wins.
Got a specific size in mind? We’ll quote it free of charge — answer within 24 hours.
➜ Get in touch with Gym Assistance
➜ Build your spec and get a price
➜ Container gyms — standard models
➜ How to choose your container gym size