Demand Planner & Buyer

Thrivin; Hemel Hempstead; On-site; GBP 65,000 - 90,000; Full time

Job summary

Thrivin is seeking an experienced Demand Planner & Buyer to own the planning and buying process across the business. You will manage sales forecasts, open-to-buy, PO placement, replenishment and inventory optimisation, working with product, operations and commercial teams to support growth.

With 5+ years in apparel planning or related fields, you will drive decisions with a commercially sharp, hands-on approach and lead improvements in planning, reporting and supplier coordination.

Qualifications

• 5+ years' experience within apparel planning, merchandising, buying or a closely related field.
• Directly owning an open-to-buy and making commercial buying decisions.
• Hands-on experience creating and placing purchase orders.
• Strong understanding of planning fundamentals (weeks of cover, sell-through, size curves, in-stock rate, gross margin, discount rate).
• Experience with supplier-facing activities (proforma invoices, MOQs, lead times, order chasing).

Responsibilities

• Own the open-to-buy by category, including sales forecasts and monthly plan vs actual performance.
• Run the bi-weekly replenishment cycle end-to-end, from demand analysis to PO submission.
• Determine newness buy quantities by style, colour and size, aligned with launch dates and targets.
• Own full purchase order lifecycle from PO creation to delivery tracking and supplier follow-ups.
• Maintain healthy stock levels and in-stock rates across categories.
• Monitor inventory performance and identify stock risks, shortages and excess inventory.
• Own markdown and overstock actions to optimise sell-through.
• Analyse planning metrics: weeks of cover, sell-through, size curves, gross margin, discount rate, in-stock performance.
• Deliver planning read and insights during weekly and monthly trade reviews.
• Collaborate with suppliers on proforma invoices, MOQs, lead times and delivery timelines.
• Identify discrepancies early to prevent impact on buying decisions and inventory.
• Continuously improve planning processes as Thrivin scales.

Skills

Open-to-buy planning

Purchase orders

Inventory management

Excel proficiency

Data analysis

Supplier coordination

Forecasting

Claude Code/Cowork

High-growth ecommerce

Tools

Claude Code / Claude Cowork

Job description

Thrivin is a fast-growing global activewear brand operating in a high-volume, fast-paced ecommerce environment. As we continue to scale internationally, we're looking for an experienced Demand Planner & Buyer to take ownership of our demand planning, purchasing and inventory management across the business.

This is a highly hands-on role for someone who is commercially sharp, analytical and comfortable taking full ownership. You'll play a critical role in ensuring we have the right product, in the right quantities, at the right time, balancing availability, inventory health and commercial performance.

The Role

As Demand Planner & Buyer, you will own the planning and buying process from sales forecasting and open-to-buy management through to purchase order placement, replenishment and inventory optimisation.

You'll work closely with the wider product, operations and commercial teams, providing clear recommendations and insights to support trading decisions and future growth.

Key Responsibilities

• Own the open-to-buy (OTB) by category, including sales forecasts, receipt plans and monthly plan vs. actual performance.
• Run the bi-weekly replenishment cycle end-to-end, from analysing demand and stock requirements through to PO submission.
• Determine newness buy quantities at style, colour and size level, ensuring buys are aligned with launch dates, expected demand and commercial targets.
• Own the full purchase order lifecycle, including PO creation, submission, amendments, invoice reconciliation, ETA tracking and supplier follow-ups.
• Own inventory management across categories, maintaining healthy stock levels and strong size availability and in-stock rates.
• Monitor inventory performance and proactively identify potential stock risks, shortages and excess inventory.
• Own markdown and overstock actions, recommending commercially appropriate strategies to optimise sell-through and inventory health.
• Analyse key planning and trading metrics including weeks of cover, sell-through, size curves, gross margin, discount rate and in-stock performance.
• Deliver the planning read and key insights during weekly and monthly trade reviews.
• Work directly with suppliers on proforma invoices, MOQs, lead times, purchase orders and delivery timelines.
• Identify discrepancies, risks and unusual data points early and investigate them before they impact buying or inventory decisions.
• Continuously improve planning processes, reporting and ways of working as Thrivin scales.

About You

We're looking for someone who has personally owned planning and buying decisions within an apparel environment. You won't simply have supported an OTB or PO process, you'll have been directly accountable for it.

Experience & Technical Skills

• 5+ years' experience within apparel planning, merchandising, buying or a closely related field, ideally within a high-volume ecommerce or retail environment.
• Previous management or leadership experience is preferred.
• Demonstrable experience personally owning an open-to-buy and making commercial buying decisions.
• Hands-on experience creating and placing purchase orders.
• Strong understanding of planning fundamentals, including:
• Weeks of cover
• Sell-through
• Size curves
• In-stock rate / availability
• Gross margin
• Discount rate
• Inventory turn and stock health
• Strong supplier-facing experience, including working with proforma invoices, MOQs, lead times and order chasing.
• Advanced proficiency in Excel and confidence working with large datasets.
• High proficiency using Claude Code and/or Claude Cowork to improve efficiency, analysis and workflows.
• Experience within a high-growth DTC, ecommerce, fashion or activewear business would be highly advantageous.

Why Join Thrivin?

This is an opportunity to take meaningful ownership of a critical commercial function within a rapidly scaling global ecommerce brand. You'll have significant autonomy, direct visibility into business performance and the opportunity to help shape how Thrivin approaches demand planning, buying and inventory management as we continue to grow.