Delivery windows: how time slots transform your routes

The time window: constraint or lever?

Many carriers see slots as a constraint that complicates planning. It's the opposite: a well-calibrated window is an optimisation lever. It tells the engine when a stop can be served, letting it build a coherent sequence instead of inheriting impossible promises.

Why it pays

The last mile represents up to 41% of total supply-chain costs, according to the Capgemini Research Institute. Every kilometre counts. A window that's too tight ("9:00 sharp") forces detours; a reasonable window ("9–11am") lets the algorithm group stops that are close in time and space. The result: fewer empty kilometres, more stops per route.

The second benefit: fewer failures

An absent recipient is expensive. According to industry analyses, the first-attempt failure rate sits between 8% and 20% of parcels depending on country and carrier. Giving the customer a slot — then confirming with an "out for delivery" notification — cuts those failures by around 25 to 35% per the same analyses: the customer knows when to be in.

Finding the right balance

The craft lies in negotiating windows wide enough to stay optimisable, precise enough to be kept. A few principles:

• Prefer 2-hour slots over fixed times, unless the business requires otherwise;
• Segment by area: a dense zone tolerates tighter windows;
• Reserve priority slots for customers who genuinely value them;
• Track window-adherence as a KPI in its own right.

With dropfleet

The dropfleet optimisation engine treats delivery windows as a native constraint: it rejects impossible sequences and warns the dispatcher upfront. The customer gets real-time tracking — the promise becomes measurable.

Routes that keep their promises. Try dropfleet free for 14 days — no credit card, ready in 5 minutes.