Senior Demand Planner & Buyer — High-Growth Activewear

Thrivin; Sheffield; On-site; GBP 42,000 - 64,000; Full time

Job summary

Thrivin is seeking an experienced Demand Planner & Buyer to own planning and buying across our high-volume ecommerce business. You will manage forecasts, open-to-buy, POs and inventory health, partnering with product, operations and commercial teams to support growth.

You will directly influence stock availability, assortment freshness and margin performance, ensuring timely buys and optimal stock levels as Thrivin scales globally.

Qualifications

• 5+ years of experience in apparel planning, merchandising or buying in high-volume ecommerce/retail.
• Hands-on experience creating and placing purchase orders.
• Strong planning fundamentals: weeks of cover, sell-through, size curves, in-stock rate, gross margin, discount rate, inventory turn.

Responsibilities

• Own open-to-buy by category, including sales forecasts and monthly plans.
• Run bi-weekly replenishment end-to-end from demand to PO submission.
• Determine newness buy quantities by style, color and size with launch dates and targets.
• Own full PO lifecycle: creation, submission, amendments, invoicing and ETA tracking.
• Maintain healthy stock levels and strong size availability and in-stock rates.
• Monitor inventory performance and identify stock risks, shortages and excess inventory.
• Lead markdowns and overstock actions to optimise sell-through.
• Analyse weeks of cover, sell-through, size curves and margin metrics.
• Present planning readouts and insights during weekly/monthly trade reviews.
• Collaborate with suppliers on proforma invoices, MOQs, lead times and deliveries.

Skills

Open-to-buy ownership

Forecasting accuracy

PO management

Excel proficiency

Data analysis

Supplier management

Tools

Claude Code and/or Claude Cowork

Job description

Thrivin is seeking an experienced Demand Planner & Buyer to own planning and buying across our high-volume ecommerce business. You will manage forecasts, open-to-buy, POs and inventory health, partnering with product, operations and commercial teams to support growth.

You will directly influence stock availability, assortment freshness and margin performance, ensuring timely buys and optimal stock levels as Thrivin scales globally.