Lead time math: How to predict when your order will actually arrive

A formula and worked example so you can promise customers a realistic delivery date — not just optimism.

Why "30 days" is usually a lie

Most suppliers quote "30 days lead time" by default, regardless of whether it's accurate. They want the deal. The actual journey from order to your warehouse has four phases — and each one can slip.

The four phases

Phase 1 — Production (5–25 days)

Depends on the product. Off-the-shelf: 5–10 days. Light customisation: 12–18 days. Heavy OEM with custom moulds: 25+ days. Production typically only starts after your deposit clears (1–3 days).

Phase 2 — Pre-shipment (2–7 days)

Inspection (1–2 days), payment of balance (1 day), booking the vessel (2–4 days). If you're shipping LCL, also add 2–3 days for consolidation at the origin port.

Phase 3 — Sea freight (18–28 days)

Vessel transit. Pad for transshipment ports, weather, port congestion. Cape Town congestion in particular has averaged 5–8 extra days through 2025.

Phase 4 — SA arrival (3–10 days)

Port clearance (1–3 days normal, 5+ in congestion). Customs entry & release (1–3 days). Last-mile to your warehouse (1–4 days depending on city).

The formula

Total lead time = Production + Pre-shipment + Sea freight + SA arrival + buffer

Plugging in realistic ranges for a typical electronics order:

• Production: 18 days
• Pre-shipment: 5 days
• Sea freight: 25 days
• SA arrival: 7 days
• Buffer: 7 days

= 62 days. Not 30.

How much buffer to add

BestDealz SLA promises

We publish a single landed lead time per Class B product (e.g. "35–45 days door-to-door"). Behind that number we've already added phase-by-phase buffers based on historical performance.

If we miss by more than 7 days against the upper bound, you automatically receive a 5% account credit — applied to your next order. No claim form, no negotiation. This is part of Trade Assurance and is enforced in our supplier contracts.