The rent does not know who came

The lease, the utilities, the cleaning and the furniture are paid per square metre and per year: none of these items knows how many people came to the office. The empty desk costs exactly as much as the full one — and since hybrid work halved attendance, this accounting truism has become one of the largest hidden costs in companies.

This calculator runs the two counts that facility and finance look at together: the annual cost per desk (what the office costs on paper) and the cost per used desk (what it really costs, divided by who shows up). The ratio between the two is the vacancy index, and the difference multiplied by the desks is the silent budget of emptiness.

The reference — 400 per m² all inclusive, 12 m² per desk, 800 of fit-out, 100 desks, 55% average attendance — gives 5,600 per desk on paper and 10,182 per used desk: whoever is present pays for nearly two.

The formula: four costs and one divisor

The cost per desk is a simple sum: annual cost per m² times the m² of each desk, plus the yearly share of furniture and IT — 400 × 12 + 800 = 5,600. Multiplied by the 100 desks, the portfolio costs 560,000 a year, whoever comes or does not come.

The second count introduces the one number the lease does not contain: attendance. Dividing the cost by the share of occupied desks — 5,600 / 0.55 — gives the cost per used desk: 10,182. It is not a theoretical number: it is what the company pays in office for every person who actually uses it.

The vacancy index is the ratio of the two, that is 100 divided by attendance: 1.82× at the reference. It is dimensionless and works in any currency and city: it says how many desks each person present pays for.

How to read the vacancy index

With attendance from 80% up (index up to 1.25) the portfolio is sized on real use: the risk, if anything, is the peak that finds no seat. Between 60 and 80 the index stays below 1.67: it is the physiological balance, the margin that absorbs holidays, sickness and travel.

Between 40 and 60 — the band where most hybrid offices live — every person present pays for nearly two desks: hybrid is here, the savings are not, because the square metres did not follow the attendance. Below 40% the under-use is structural: more than half the portfolio runs empty all year, and the issue is not tuning but perimeter — subletting, releasing floors, renegotiating.

The threshold between zones is not cosmetic: it marks which lever to use — booking rules in the central band, square metres in the low one.

The attendance scale

The table keeps the reference portfolio fixed — same leases, same 100 desks, same 5,600 per desk — and moves only the average attendance.

The paper cost is identical in every row — the office has not changed by a metre — but the real cost per person present multiplies by 3.6 between the first and the last row. At 40% every person present pays for exactly two and a half desks; at 25%, four: the half-empty Friday office is, in accounting terms, the most expensive in town for those who go.

It is the table to bring to the board when the attendance policy is discussed: every extra point of attendance dilutes the same rent over more people — for free.

The cost of emptiness: the hidden budget

Multiplying the desk cost by the desks and the empty share, the reference spends 252,000 a year on desks nobody uses: 45 equivalent desks always empty, a whole floor paid not to work. It is more than the training budget of many same-size companies, and it is invisible because it is spread over leases signed years ago.

The number deserves the name it has: budget. It is the rational ceiling of any project that reduces it — booking software, refurbishment for desk sharing, relocation, early-exit penalty. If the project costs less than the emptiness it removes, it pays for itself.

And it is why the count must be done before the next lease expiry: emptiness is only cashed in the windows when the square metres become negotiable again.

The m² per desk: where half the count hides

The reference's 12 m² surprise anyone thinking of the desk itself: a workstation takes 4-6 net m². The rest is the share of everything around it — meeting rooms, corridors, reception, kitchens, technical rooms: in offices the common areas typically weigh 40-50% of the total surface.

The right number is computed one way only: total contracted surface divided by fitted desks. Using the desk-only metres halves the cost per desk and turns the comparison with coworking into self-deception — coworking prices everything included, and must be compared with the full cost.

The design consequence: densifying desks without touching the common areas moves little, because it compresses only the half of the count that was already the smaller one.

Average and peak: Tuesday decides

The average attendance says how much the emptiness costs; the peak says how many desks are needed. An office at 55% average with Tuesdays at 85% cannot cut 45% of the desks: it can cut 15%, plus whatever booking rules recover by spreading the peaks.

It is the arithmetic of desk sharing: the sustainable people-per-desk ratio is set by the peak, not the average — and every peak point shaved by coordinating teams (who comes when) is worth real desks. Companies that fail at desk sharing almost always cut on the average and discovered Tuesday.

The honest count therefore uses two attendance numbers: the average to measure the cost of emptiness (this page), the peak to size the cut (badge data, week by week).

The desk inside the employee cost

The 5,600 per desk — 10,182 per used desk — must be read next to the labour cost: for an average salary, the office typically weighs between 5 and 15% of an employee's full cost, the second item after pay itself in many headquarters budgets.

That proportion explains both wrong rhetorics: whoever says "the office costs nothing compared to salaries" ignores that it is still the second cost; whoever promises to "halve costs with smart working" forgets that the real estate part is cashed only at lease expiries, not when the policy launches.

The complete employee count — pay, charges, equipment and their share of office — is this page's twin: the true cost of an employee looks at the person, this one looks at the seat.

The cost per used desk is also the number that makes alternatives comparable. The coworking asking 4,000 a year per desk looks expensive against the 5,600 of the headquarters — but it must be compared with the 10,182 of the used desk: for small or distributed teams, flexible wins precisely because it does not pay the emptiness.

Subletting flips the same count: every equivalent empty desk rented to third parties recovers up to its entire annual cost — which is why large portfolios with structural emptiness sublet whole floors before expiry.

The comparison rule is one: every option is priced per used desk, never per nominal desk — it is the only price that includes real attendance.

Mistakes that distort the count

The first is attendance by impressions: "the office is always full" said from the floor where the decision-makers sit — badges and sensors often tell of a building at 50% with one floor at 80%. The second is the non-full cost per m²: the bare rent without utilities, cleaning, security and local taxes understates the count by 20-40%.

The third is forgetting the fit-out: furniture, monitors, cabling and workstation maintenance are worth hundreds a year even amortised. The fourth is cutting on the average while ignoring the peak — the Tuesday mistake already seen. The fifth is treating the emptiness as a "cost of the past": at every lease renewal it becomes a choice again.

The last is one of perspective: this is a parametric estimate of cost, not a judgement on hybrid work — the right attendance is decided by productivity and people; here you only measure what the portfolio hosting it costs, together with its twin on time: the cost of meetings, the office's other silent bill.

The scale of the city

The first table keeps metres, fit-out and attendance (55%) fixed and moves only the cost per m² — from the secondary city to the business district of the financial capital.

The cross-reading is the most instructive: the nominal desk in the expensive city (11,600) costs double the used desk in the cheap one (5,818) — that is, the empty downtown desk is worth two full desks in the periphery. It is the arithmetic behind hub-and-spoke strategies: the small, full flagship office downtown, the daily work where the metre costs a third.

It is also why the cost of emptiness is not equal everywhere: the same 45% of empty desks is worth 144,000 a year at 200 per metre and 522,000 at 900 — attendance discipline pays most precisely where the office is most prestigious.

The scale of density

The second table moves the m² per desk — from the dense open space to the generous office with many rooms — all else equal.

From 8 to 20 m² the cost per desk more than doubles — but the honest reading goes both ways. Pure densification (more desks in the same metres) cuts the nominal cost and often raises noise, failed bookings and dissatisfaction: savings that the reverberation and air-change pages know how to describe.

The modern direction is different: fewer desks, not tighter ones — use the low attendance to remove whole desks and give the metres back to rooms, phone booths and project areas. The cost per desk can even rise while the total cost falls: it is the sign of a portfolio following the use.

The rules that raise attendance for free

Of the two levers — cutting metres and raising attendance — the second touches no contracts: every extra attendance point dilutes the same rent over more people. The rules that work are known: anchor days per team (the group comes together, collaboration justifies the trip), events and rituals on weak days, coordination between teams sharing projects.

The rule that does not work is the generic mandate: it produces resentful attendance on the wrong days — Monday and Friday stay empty, Tuesday explodes beyond the peak, and the cost of emptiness moves without falling.

The page's count gives the monetary value of each point: at the reference, moving from 55 to 65% is worth 56,000 a year less emptiness — a number that turns the policy discussion from ideological to financial.

Expiries: when the emptiness becomes negotiable

The cost of emptiness accrues every day but is cashed only at contractual windows: expiries, break options, renewals. The operating sequence is therefore a calendar: twelve to eighteen months before the window, measure average and peak attendance; six to twelve months before, decide the perimeter (how many metres are really needed); at the window, renegotiate, downsize or sublet.

Whoever reaches the expiry without data signs the photocopy renewal — and the emptiness restarts for another six years. Whoever arrives with data holds the knife by the handle: the post-hybrid office market rewards tenants who know exactly how much space they want.

Meanwhile the emptiness is not immobile: subletting whole floors, where the lease allows it, turns equivalent empty desks into revenue — the only way to cash in before the window.

The fit-out: the cost nobody adds up

The reference's 800 — 14% of the desk cost — cover what the rent does not contain: amortised desk and chair, monitors and docking, cabling, maintenance, the cyclical renewal of furniture. In company accounts these items live in three different budgets (facility, IT, procurement) and never meet on a single line: which is why the "official" desk cost is almost always understated.

Desk sharing has an accounting consequence often ignored: the shared desk is fitted better — dual monitors, universal docking, adjustable chair — because it must serve anyone. The fit-out per desk rises 20-30% while the desks fall: the net saving remains, but it is smaller than the one promised on metres alone.

The rule: the count includes everything that exists because the desk exists — if the desk disappeared tomorrow, which invoices would disappear with it?

Multiple sites: the portfolio count

In companies with several sites the count must be done site by site, because the average hides the decisions: site A at 75% and site B at 30% give a respectable average and two opposite verdicts — the first is kept, the second is consolidated into the first or closed at expiry.

Consolidation is the real estate version of desk sharing: two half buildings become one full one, and the cost of emptiness of both finances the move. The symmetrical mistake is closing the small, full site to "rationalise" while keeping the large, empty one: the cost per used desk unmasks the operation in one line.

For the distributed portfolio the same arithmetic governs the choice between satellite office and coworking: below a certain team size, the used flexible desk costs less than the half-empty headquarters desk — and the calculator says exactly where that threshold sits.

Frequently asked questions

How do you calculate the cost of a desk?

Annual all-inclusive cost per m² times the desk's m² (common-area share included), plus the yearly fit-out of furniture and IT. The page reference — 400 × 12 + 800 — makes 5,600 a year per desk, before even asking who uses it.

What is the cost per used desk?

The desk cost divided by average attendance: at 55% the nominal 5,600 become 10,182 — it is what the company pays in office for every person who actually goes. It is the right number for comparing coworking, flexible offices and headquarters.

What is the vacancy index?

100 divided by average attendance: it says how many desks each person present pays for. It is dimensionless — it works in any currency and city. Up to 1.25 full occupancy, up to 1.67 balance, up to 2.5 uncashed hybrid, beyond that structural under-use.

How many m² does a desk count?

The total contracted surface divided by fitted desks: typically 8-15 m², because it includes the share of meeting rooms, corridors and common areas (40-50% of office surface). The 4-6 m² of the desk alone halve the count and distort every comparison.

Which average attendance should I use?

The measured one — badges, sensors, bookings — over a representative period, not impressions. Buildings "always full" as seen from the executive floor are often at 50% overall with one floor at 80%.

Why has hybrid work not reduced costs?

Because it halved the use, not the square metres: the rent does not know who came. Until the portfolio follows the attendance — at lease expiry, with subletting or consolidation — the promised saving remains a cost of emptiness: 252,000 a year in the reference.

Can I cut desks in proportion to attendance?

No: the cut is sized on the peak, not the average. An office at 55% average with Tuesdays at 85% can remove about 15% of desks, plus whatever booking rules recover by spreading peaks — cutting 45% means discovering Tuesday.

Is desk sharing always worth it?

It pays when the gap between average and peak allows it and when the project cost (booking software, lockers, refit) is below the cost of the emptiness it removes — 252,000 a year in the reference: almost any reasonable project pays back, but the count must come first.

How do I compare headquarters and coworking?

Per USED desk, never nominal: coworking at 4,000 looks expensive against the 5,600 of the headquarters, but the headquarters at 55% attendance costs 10,182 per used desk. Flexible wins for small or distributed teams precisely because it does not pay the emptiness.

How much does the office weigh on an employee's cost?

Typically between 5 and 15% of the full cost, the second item after pay in many headquarters budgets. It is not "negligible next to salaries", but neither is it the lever that halves costs overnight: the real estate part is cashed at lease expiries.

Is the cost of emptiness real or notional?

Real: it is rent, utilities and services already paid for surfaces that produce no attendance. It is "notional" only in the sense that no invoice names it — which is why the calculator isolates it: 45 equivalent empty desks are a whole floor paid not to work.

Does this count judge remote work?

No: it measures the cost of the real estate portfolio given an attendance, whatever it is. How much attendance is right is decided by productivity, collaboration and people; the calculator only says what the current setup costs and what each alternative choice is worth, in money.

Updated July 2026