Blended Rate Calculator

How the Blended Rate Calculator works

Blended rate calculator: weighting by hours

A blended rate is one hourly figure charged for every person on a project regardless of seniority. It is a weighted average of the role rates, weighted by the hours each role actually works — and the weighting is the entire point.

Weight by hours, not by headcount. Averaging $200, $140 and $95 gives $145. Weighting those rates by 40, 120 and 80 hours gives $134. The difference is not rounding: it is $2,640 on a 240-hour project, and it exists because the expensive role works the fewest hours. Taking the simple average of a rate card is the single most common way blended rates are set too high to win work or, when the senior role is the busy one, too low to deliver it.

The staffing mix is the assumption that breaks. A blended rate is only correct for the mix it was calculated from. Projects reliably drift toward more senior time than planned — the tricky parts escalate, the junior work finishes early, the client asks for the principal in the weekly call. If you quote $134 and then staff twice the planned senior hours, the blended rate no longer covers the work and the loss appears at the end of the project rather than at the start. Quote a blended rate against a staffing plan, and treat a material change to the mix as a change to the fee.

Why clients like it and why agencies offer it. For the client, one number makes the budget predictable and removes the suspicion that expensive people are being assigned to cheap tasks. For the agency, it removes the friction of justifying a senior rate on a task a client thinks is junior, and it simplifies invoicing. Both benefits are real. The cost is that all the risk of the mix moves to whoever quoted the rate.

Check it against your cost floor, not just your rate card. A blended rate that averages your published rates can still lose money if utilisation is poor or overhead is high, because rate cards are set with assumptions about both. The safe check is total cost per billable hour — direct labour plus overhead recovery — against the blended rate you are quoting. If the blended rate is below the loaded cost of the mix, the project loses money on every hour no matter what the rate card says.

Build in a buffer, deliberately. Where the mix is genuinely uncertain, quoting the blended rate of the pessimistic staffing plan rather than the expected one is cheaper than renegotiating mid project. A five to ten percent buffer over the calculated rate is normal practice and is far easier to defend at the proposal stage than a change order in month three.

Blended rate table by senior share

A 240-hour project staffed by a senior at $200 an hour and a junior at $100 an hour, with the split between them moving 10 hours at a time.

Blended hourly rate for a 240-hour project as the senior share grows

Blended rate formula and worked examples

The formula: blended rate = Σ(hours × rate) ÷ Σ hours. It is a weighted average, so a role with more hours pulls the blend towards its own rate.

First example. a project uses 10 hours of a partner at £200, 40 hours of a senior at £120 and 50 hours of a junior at £70. The fee is 2,000 + 4,800 + 3,500 = £10,300 over 100 hours, a blended rate of £103.

Second example. quote that job at a blended £95 and the same 100 hours bring in £9,500, a shortfall of £800 or 7.8%. Move 10 senior hours to the junior and the cost falls to £9,800, a blend of £98 — still above the quote.

How many hours can each role take? Fix the blended rate and total hours, then shift hours from the dearest role to the cheapest until Σ(hours × rate) equals the quoted fee.

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