Fit-Out Timeline Calculator: How Long Will Your Office Take?
A fit-out timeline estimate adds design, approvals, site works, procurement, installation and handover into one programme. Site works and long-lead procurement run in parallel, so whichever takes longer sets the handover date. That phase is the critical path.
By Dhruv Agarwal · · 4 min read
Fit-out timeline estimator
Use 0 if approved working drawings already exist.
Order to delivery for the slowest item, e.g. imported furniture or HVAC units.
Assumptions (edit to match your project)
Area completed through civil, MEP, ceiling and finishes each week.
Indicative programme
18 weeks
About 4.2 months
Site works
7.7 weeks
Mobilisation to finishes
Critical path runs through
Procurement
The 8-week lead item, not the site, sets the date
From approval to handover
11 weeks
Programme
Darker bars are on the critical path.
How this was calculated
- Site works = 1 + (10,000 / 1,500) × 1 × 1 = 7.7 weeks
- Parallel stage = max(site works 7.7, lead item 8) = 8 weeks
- Total = 4 + 3 + 8 + 2 + 1 = 18 weeks
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Send on WhatsAppIndicative figures for early planning, based only on the inputs and assumptions above. This is not a design, a quotation or a compliance check. A qualified engineer or consultant must confirm any figure before it is used to order, build or sign.
What it calculates
The estimator builds an indicative fit-out programme in weeks, from the start of design to handover. It shows:
- the total programme in weeks and months;
- the site works duration, from mobilisation to finishes;
- which phase sits on the critical path, site works or procurement;
- the time from approval to handover;
- a simple bar chart of the phases, with the critical ones highlighted.
Inputs
Carpet area is the area being fitted out.
Starting condition describes what is already there. A bare shell has no ceiling, air conditioning or lighting. A warm shell has them in place, so less work is needed. An existing office has to be stripped out before new work starts.
Working hours allowed by the building reflects the landlord's rules. In occupied buildings, noisy work is often limited to nights and weekends.
Design and drawings is the time to produce approved working drawings. Enter zero if they already exist.
Landlord and authority approvals is the wait between submitting drawings and receiving permission to start.
Longest lead item is the time from order to delivery for the slowest item on the project, often imported furniture, specialist glass or HVAC equipment.
The assumptions panel holds the weekly site progress, mobilisation, installation and commissioning, and the handover period.
Method
The programme runs in five stages. The third stage has two activities in parallel:
- Design and drawings.
- Approvals.
- Site works and long-lead procurement, both starting when approval is received. Site works = mobilisation + (area ÷ weekly progress) × condition factor × hours factor.
- Furniture installation, testing and commissioning, which starts when both the site works and the long-lead delivery are complete.
- Snagging and handover.
Total = design + approvals + the longer of site works and procurement + installation + handover.
Assumptions
| Assumption | Default | Notes |
|---|---|---|
| Site progress | 1,500 sq ft a week | Area taken through civil, MEP, ceiling and finishes each week |
| Mobilisation | 1 week | Site set-up, protection, permits to work |
| Bare shell factor | 1.0 | The reference case |
| Warm shell factor | 0.75 | Less ceiling and services work |
| Existing office factor | 0.9 | Strip-out first, but some services may be reused |
| Night and weekend factor | 1.4 | Shorter, less productive shifts |
| Installation, testing and commissioning | 2 weeks | Furniture, then testing of services |
| Snagging and handover | 1 week | Defects list, cleaning, documents |
Weekly progress depends heavily on the specification and the size of the team on site. A simple open-plan office progresses faster than a floor of cabins, glass partitions and detailed joinery. Change the figure to suit the project.
Limitations
- It assumes approvals arrive in one go. In practice, landlords often comment and ask for resubmission, and each round adds time.
- It treats site works as one block. A real programme overlaps trades and tracks dozens of activities, some of which depend on deliveries other than the longest one.
- It assumes the order is placed on approval. If decisions on furniture or finishes are late, procurement starts late and the programme moves with it.
- It does not allow for client changes. Changes after work has started are one of the most common causes of delay.
- It ignores external events. Authority inspections, power connections and building works by the landlord can all hold up handover.
Worked example
A 10,000 sq ft bare-shell office, normal working hours, four weeks of design, three weeks of approvals and an eight-week lead time on imported furniture:
| Phase | Calculation | Weeks |
|---|---|---|
| Design and drawings | entered | 4 |
| Approvals | entered | 3 |
| Site works | 1 + (10,000 / 1,500) × 1.0 × 1.0 | 7.7 |
| Long-lead procurement | entered | 8 |
| Parallel stage | the longer of 7.7 and 8 | 8 |
| Installation and commissioning | assumed | 2 |
| Snagging and handover | assumed | 1 |
| Total | 4 + 3 + 8 + 2 + 1 | 18 |
The programme is about 18 weeks, a little over four months. Procurement, not the site, sets the date: the furniture arrives a few days after site works finish. Placing the order two weeks earlier, for example by approving the furniture during design, would bring handover forward by the few days procurement is ahead of the site.
If the same floor can only be worked at nights and weekends, site works stretch to about 10.3 weeks and become the critical path. The programme grows to about 20.3 weeks, and ordering early no longer helps.
How engineers use it
A project manager builds the programme in the same way: fix the dates that cannot move, identify the long-lead items, and find the chain of activities that sets handover. The difference is detail. A real programme breaks site works into trades and areas, links them with dependencies, and tracks deliveries item by item.
The most useful output at the early stage is knowing what is on the critical path. If it is procurement, the decisions that matter are about ordering early. If it is site works, they are about working hours, labour on site and avoiding changes.
When a professional design must replace it
Use the estimator to set expectations, to test what a later lease start or a night-only rule does to the date, and to decide which decisions must be made early. Replace it with a contractor's detailed programme before you commit to a move-in date, a lease start or a notice period on your current premises, and keep that programme updated as the project runs.