What is a fractional CTO?

The word doing the work is "fractional", not "advisor"

The role is often described as advisory, which undersells it and causes most of the disappointment people report. Fractional describes the time, not the accountability. A fractional CTO is not a consultant who visits, and is not a mentor who asks good questions. They own outcomes, and if the architecture is wrong in eighteen months it is their name on it.

What is genuinely reduced is availability. You are buying a fraction of a person, which means you get their judgement on the decisions that matter and you do not get them for the day-to-day. That trade works because most companies of 10 to 150 people generate roughly two days a month of decisions that actually require a CTO, and roughly twenty days a month of work that does not.

What a fractional CTO actually does

The specifics vary, but the mandate is consistent across every engagement worth the name.

• Owns the technology roadmap: sequenced, costed, and defensible against what the business is trying to do this year rather than a wishlist of features
• Signs off architecture: nothing significant ships without a design reviewed against where the company will be in eighteen months
• Makes vendor decisions: including saying no to a vendor the founder already likes, which is most of the value
• Owns technical hiring: writing the brief, screening for real ability, and sitting on the panel
• Reports to the board: translating technical position into the language investors and directors actually assess
• Holds delivery accountable: whether the people building are in-house, an agency, or both

How it differs from everything adjacent

Four roles get conflated with this one, and the differences are not academic: they determine who is accountable when something goes wrong.

The line that matters most is the third column. If nobody is accountable after the document lands, you bought consulting. That can be exactly the right purchase, but it is a different purchase.

When a company needs one

Almost nobody goes looking for a fractional CTO by job title. They go looking for relief from a specific, recurring problem. Three or more of these being true is the usual threshold.

• Six-figure technology decisions are being made with nobody senior to pressure-test them
• The founder is the most technical person in the room, and it is not their job
• Vendors contradict each other and there is no way to arbitrate
• Delivery dates move and nobody can explain why in terms the business can act on
• An investor or board has started asking technical questions being answered by forwarding emails
• There are engineers, but nobody deciding what they should be building

The inverse is also worth stating. If you have fewer than about ten people, no meaningful technology spend, and one clear thing to build, you do not need a fractional CTO. You need a good developer and a short brief.

What it costs, structurally

Pricing is usually a day rate or a monthly retainer covering an agreed number of days, sometimes opening with a fixed-scope diagnostic. Equity occasionally appears in early-stage arrangements and is worth treating with more suspicion than founders typically apply, because equity aligns incentives over years and most fractional engagements are measured in quarters.

The comparison people reach for is the rate against a CTO salary, and it is the wrong one. The right comparison is against the cost of the decisions currently being made without help. A CRM migration that fails twice, a platform rebuilt three years early, or an AI pilot with no baseline that nobody can defend or kill will each cost more than a year of fractional engagement.

How to tell a good one from an expensive one

The interview signal that predicts everything is whether they will tell you that you do not need them. Someone who agrees enthusiastically with your framing in the first call is selling; someone who reframes the problem, or says the honest answer is to hire an operations person instead, is doing the job before you have paid them.

Beyond that: ask what they will write down and hand over, ask who owns the architecture document, and ask whether they take referral fees or partner commissions from vendors. That last answer tells you how much any future vendor recommendation is worth.

Frequently asked

How many days a month does a fractional CTO work?

Two to six is the usual range. Two suits a company that mainly needs architecture review and vendor arbitration; six suits one running an active build with engineers who need weekly direction. Starting low and adjusting upward is safer than the reverse.

Is a fractional CTO the same as a part-time CTO?

Effectively yes, and the terms are used interchangeably. "Fractional" has become the more common label because it implies working with several companies rather than holding one reduced-hours job, which is how most of these arrangements actually run.

Does a fractional CTO write code?

Some do, some do not, and you should establish which before signing. Many implement smaller systems directly and orchestrate larger programmes. What you should not be paying a CTO rate for is routine development work that a developer could do more cheaply.

How long do fractional CTO engagements last?

Most open with a two-to-three-week paid diagnostic, then run monthly with no long lock-in. Some close cleanly within a quarter once the architecture is set and a team can execute it. Others run for years, usually because the business keeps generating decisions worth having help with.

Can a fractional CTO help us hire a full-time one?

Yes, and a good one will raise it themselves when the company outgrows the arrangement. That means writing the role brief, screening the shortlist technically, sitting on the panel and handing over the architecture documentation cleanly.