Big Rocks Planning, and why it's a great way to start prioritization

Big Rocks: A simple model for a complex challenge

Most organisations have more worthwhile work than they can support at the same time. Some commitments are large and strategic. Others are smaller but operationally important. All of them draw on finite funding, capacity and attention.

Big Rocks planning is a simple way to make that constraint visible before the planning conversation disappears into project lists, scores and competing requests.

The Big Rocks model (a quick refresher)

Derived from Stephen Covey’s time management principle, the concept is deliberately simple.

You have a jar to fill. You can add:

• Big Rocks
• Pebbles
• Sand

If you start with the Big Rocks, smaller items can use the space that remains.

If you start with the sand, you risk crowding out the Big Rocks.

The parallel to portfolio planning is hard to miss.

• Big Rocks are your key strategic initiatives. They often have high potential impact and may require significant funding, cross-team capacity and leadership commitment.
• Pebbles are important divisional or operational initiatives. Critical to their sponsors, but with less enterprise‑wide impact. Until something breaks.
• Sand is the stream of smaller asks, fixes and changes that may each make sense in isolation but collectively consume meaningful capacity.

And the jar is your available capacity.

It is the reason you cannot support everything at once. Leadership decides which commitments deserve that capacity; portfolio and planning teams can make the limits, alternatives and consequences visible.

That is the real portfolio problem.

Not a lack of ideas.

Not a lack of ambition.

But worthwhile work competing for finite resources.

That simplicity is what makes Big Rocks useful. It gives people an intuitive way to talk about priorities and finite capacity before getting into the detail.

Five Ways to Use Big Rocks in Portfolio Planning

1. Sand gets everywhere

The trouble with sand, as any beach‑goer knows, is that it gets everywhere.

But here’s the nuance: sand is not automatically bad. Some sand delivers quick wins, removes friction, improves service, and builds momentum.

The problem is not that sand exists.

The problem is when it is allowed to accumulate without discipline.

This is where organisations get caught out.

If the process for assessing small work is too heavy, people will route around it. Local backlogs form. Shadow portfolios emerge. The work may disappear from the formal portfolio, but it does not disappear from capacity. The jar simply looks emptier than it really is.

A better answer is proportional rigour.

Lower-level work should be assessed quickly and lightly, but with enough structure to stop hidden backlogs growing unchecked. And make sure your Sand is really Sand, not a Big Rock in disguise.

Not more time reviewing than doing, but not a free-for-all of “just one more thing” either.

2. The jar is not elastic

The jar represents capacity beyond headline headcount and budget.

That can include people, specialist skills, funding, technology, bottlenecks and organisational attention. The useful question is not what looks attractive in isolation. It is what the organisation can actually support alongside its existing commitments.

You can test capacity at portfolio level before getting into detailed resource schedules. Forward capacity planning looks at the roles, skills, technology, funding and other constraints future work will require before those commitments are fixed.

You don’t negotiate with a jar. You don’t tell it to work harder. And you can’t fit everything in by pretending things are smaller than they are.

Nor does good planning necessarily mean filling every part of the jar to 100%. Some headroom can be deliberate when bottlenecks, changing demand or uncertainty make maximum loading different from good flow.

You decide what goes in.

You use the available capacity intentionally.

And when there is no credible room for more, something else has to wait, move or come out before more goes in.

3. You can’t have all the Big Rocks

Planning processes can easily generate more Big Rocks than can realistically be delivered.

The metaphor does not tell you which initiatives deserve to be Big Rocks. That requires a repeatable prioritisation process that makes leadership judgement explicit and connects it to the resources available.

That makes selection, not ideation, the critical discipline linking strategy to portfolio management. Proposals need input from people with relevant knowledge and a consistent basis for comparing their relative value.

By structuring leadership judgements, you can assess the relative value of competing proposals.

You also need credible estimates of the funding and resources each proposal would require. Together, these inputs let leadership test what can realistically fit in the portfolio.

At this point, you can ask a simple but pivotal question:

Which Big Rocks actually fit in the jar, and which must wait?

Waiting does not necessarily mean an initiative is unimportant. Sometimes it is a sequencing decision: protect scarce capacity for work leadership has chosen to continue, then start the next valuable commitment when the required capacity is available.

That turns a list of strategic priorities into an explicit portfolio choice.

And when there is no credible room for another Big Rock, adding one creates a leadership choice: what waits, changes or gives way.

4. Keep space for Pebbles

Big Rocks planning can create an unhealthy fixation on high‑profile programmes with jazzy codenames and executive visibility.

But many initiatives with significant operational value also deserve space in your jar.

This is where a portfolio-led approach matters. Steve Jenner describes using strategic buckets for work with fundamentally different purposes, rather than forcing every investment to compete in exactly the same way.

Firstly, by grouping Pebbles into appropriate categories or strategic buckets, you can assess them in a way that reflects their purpose. Technical debt, for example, may not excite executives, but it can quietly undermine everything that does.

Secondly, by explicitly reserving some capacity for operational work, you protect space for the work that keeps the organisation functioning.

That makes the trade-off visible.

Sometimes the choice is one more Big Rock or room for several worthwhile Pebbles.

Leadership should own that choice.

After all, it all has to fit in the jar.

5. When the jar gets complicated

Of course, in reality it’s never quite this straightforward.

People debate the relative value of every stone.

Estimates shift as “T‑shirts” start looking uncomfortably tight, and you start to wonder if your Sand might actually be more of a Rock.

Then, of course, the jar turns out to be ten teams, three budget lines, several scarce skills and a hiring freeze.

And then strategy changes in Q2.

This is where the metaphor becomes a real portfolio decision. TransparentChoice helps leadership compare workable portfolio choices as priorities, funding and capacity interact. The wider planning process has to connect strategic priorities to a deliverable plan.

We use AHP to structure leadership judgements about what matters, then compare feasible combinations against funding, capacity and other constraints. That means leadership can see what each choice protects, what gives way, and what changes when priorities or assumptions change.

Leadership can choose which combination of commitments to support.

What it cannot do is make the constraints disappear by choosing more.

At the RNLI, hidden work and scarce specialist capacity became part of the portfolio decision, and the organisation later revisited its portfolio when priorities changed.

If there is no credible room for a new commitment without changing how funding or capacity is allocated, start with a Decision Review.

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