Billable utilisation
The share of a consultant's available time that a client pays for: how to work it out, and what a good rate is.
Reviewed by Hassen Hattab, founder of BenchBee Updated
Billable utilisation is the share of a consultant's available working time that is billed to a client. It is billable hours divided by available hours, as a percentage: a consultant who bills 165 of 220 available days in a year runs at 75%. Across professional services firms, IT consultancies among them, it averaged 68.9% in 2024 and fell to 66.4% in 2025, the lowest SPI Research has recorded, against the 75% SPI considers optimal.
How to calculate billable utilisation
Billable utilisation = billable hours ÷ available hours × 100.
- Billable hours. Time invoiced to a client, at any rate.
- Available hours. Working time after annual leave and public holidays. The worked example on this site uses 220 working days a year.
- The fine print. Some firms take sick days and training out of available hours, others count them in. Compare two rates only when both are worked out the same way.
Illustrative example: a consultant available 220 days a year who bills 165 runs at 75%. At about 152 billed days, the same consultant runs at 69%.
Billable utilisation, chargeability, realisation: what the words mean
| Term | What it counts |
|---|---|
| Billable utilisation | Billed time as a share of available time. |
| Total utilisation | All productive time, internal projects and pre-sales included, as a share of available time. |
| Chargeability | Another name for billable utilisation, common in UK consulting firms. |
| Realisation | The fees a firm collects as a share of its fees at standard rates. A discount lowers realisation, not utilisation. |
| Bench time | Time with no client work at all: much of what pulls billable utilisation down. |
More on the days that go unbilled: bench time.
What is a good billable utilisation rate?
SPI Research considers 75% optimal for professional services firms: between 70 and 80% has historically maximised profitability, and above 80% burnout and attrition rise. The average sits under that band: 68.9% in 2024 (403 firms) and 66.4% in 2025 (over 500 firms).
| Rate | What it usually means |
|---|---|
| Below 70% | Bench time and non-billable work are taking a large share of the margin. |
| 70 to 80% | The band SPI Research links with the best profitability. |
| Above 80% | Little slack for training, sales or cover; SPI finds burnout and attrition rise. |
Targets differ by role: a delivery consultant is expected to bill most of their time, a practice lead or a manager much less.
What one point of utilisation is worth
Salaries are paid whether a consultant bills or not, so almost every extra billed day is profit.
Illustrative example: a consultant on a £65,000 salary costs the firm about £89,250 a year once employer National Insurance, pension, benefits and overhead are added, and is billed at £650 a day. At 69% utilisation they bring about £9,400 of profit a year; at 75%, £18,000; at 80%, £25,150. For a 50-person consultancy, each point of utilisation is 110 more billed days, or £71,500 of billing a year.
The full calculation: What bench time really costs an IT consultancy.
How consultancies raise billable utilisation
Utilisation rises when fewer days go unbilled: see the gap early with a forecast, match skills to the pipeline, and fill the gaps that remain. A gap a firm can't fill from its own clients can still be billed: a consultant lent to another firm that needs their skills bills that firm a day rate, and those days count as billable like any other client work. That is talent sharing. More ways: How to reduce consultant bench time costs.
Frequently asked questions
What is billable utilisation?
Billable utilisation is the share of a consultant's available working time that is billed to a client, as a percentage.
How do you calculate billable utilisation?
Divide billable hours by available hours and multiply by 100. A consultant who bills 165 of 220 available days runs at 75%.
What is a good utilisation rate for an IT consultancy?
SPI Research considers 75% of available time billed optimal; between 70 and 80% has historically maximised profitability, and above 80% burnout and attrition rise. Professional services firms averaged 68.9% in 2024 and 66.4% in 2025.
What is the difference between utilisation and chargeability?
Most firms use the two words for the same thing: billed time as a share of available time. Check how each firm counts available hours before comparing their rates.
Is 100% utilisation a good target?
No. It leaves no time for training, sales or leave cover, and SPI Research finds burnout and attrition rise above 80%.
Does lending a consultant to another firm count as billable time?
Yes. The days are invoiced to the other firm at an agreed day rate, so they count as billable for the firm that employs the consultant.
Utilisation: SPI Research, Professional Services Maturity Benchmark 2025 (2024 data, 403 firms) and 2026 (2025 data, over 500 firms, reported by Deltek, 30 July 2026); SPI Research, “The truth about billable utilization”, 18 March 2025. The £65,000 / £650 example is illustrative, not a benchmark (the same numbers as the cost article).
Every point of utilisation is a billed day. Where will your next one come from?
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