How to solve and prevent overselling on Shopify (the easy way)

What is overselling?

Overselling in ecommerce is when a store fails to accurately update stock levels on their website, leading customers to purchase a product that’s not actually available.

Not to be confused with stockouts, which is when there is no stock left of a product available for a customer to purchase in the first place. 

‍

Why is overselling a problem?

When you oversell a product, it’s an admin nightmare. You have to contact the customer, tell them the item’s actually not available and issue a refund. But beyond the logistics of it all, it can have a serious long-term impact on your store’s reputation, customer loyalty and profitability.

Shoppers feel conned when they’re oversold a product and over 50% of them will switch to a competitor’s store after this one negative experience. 

‍

Already oversold? Here’s how to handle overselling quickly

If you’re faced with an overselling dilemma right now, these are steps you can take in the short-term to control the damage. 

Stop the flow of sales for oversold products immediately

As soon as you’re aware of overselling, stop the problem from getting any worse by immediately updating your website to clarify the product is out of stock. Do this by marking the products as sold out or hide the listing entirely. Make sure to also pause any ads or promotional material for these products too.

Co-ordinate restocks

Contact your suppliers ASAP to see if rush restocks are possible. If the answer is yes, this could be your get out of jail free card. Customers will still get their product and you’ll save yourself the refund. If the answer is no, keep calm and continue to the next step.

Audit current stock levels

Check any remaining stock and strategically reserve products for higher-priority orders like loyal customers or wholesale partners. This way, you’ll preserve your most valuable relationships. 

Communicate clearly and quickly

Let customers know as early as possible if you won’t be able to fulfil their order. Reach out to offer a genuine apology and acknowledge the inconvenience the mistake may cause. Prepare your support team and/or chat bots with a short script to handle inquiries about the product with consistent messaging. If you have an expected restock date after talking to your suppliers, then include this information in your communications and the product page. 

Offer your customers alternative options

In your message, offer customers multiple alternative options they can choose from to make up for missing out on the original product. You could offer a full refund, recommend similar products that may work instead or offer a later delivery date when the product is back in stock. This gives customers agency and allows them to choose the best option for them. It’ll also help you avoid angry one-star reviews. 

If you’re contacting a returning customer, you could check their order history to find and offer a product they’re likely to want based on past purchases. 

To truly get customers back on side, offer them a gift as a sign of goodwill. This could look like an exclusive discount code for future purchases or an alternative product bundle that exceeds the value of their original purchase. This is the extra step that’ll take your customers from frustrated to forgiving – and hopefully see them return to your store. 

How to apologize for overselling (using this ChatGPT prompt)

To craft the perfect message for your customers, copy and paste this prompt into ChatGPT, filling in the blanks:

You are an empathetic e-commerce support agent for [Your Store Name]. Write a clear and brand-aligned message to a customer letting them know that the item they ordered ([Insert Item Name]) has been oversold and is currently out of stock. The tone should be [Insert your brand tone: e.g., warm, professional, empathetic, premium].
The message should:
- Acknowledge the issue honestly (explain the stockout in simple, transparent language).
- Apologize sincerely and show empathy for the inconvenience.
- Present the following options: wait for restock with timeframe, swap for a similar item, or receive a full refund.
- Reassure the customer by explaining what happens next and emphasizing that their satisfaction is the priority.
- Stay concise and on-brand (avoid unnecessary detail or jargon).

Format the response as:
Email version → include a subject line and short, friendly body text.
Banner/chat notice version → 1–2 sentences suitable for a storefront banner or live chat message.

‍

How to prevent Shopify overselling long-term

The best solution, of course, is prevention. It’s easier than you might think to avoid overselling. You just need a smart inventory management system so you can stay on top of dangerously low stock. 

Sync inventory levels across all channels, suppliers, and partner stores 

Managing spreadsheets manually is a losing game. 40% of retailers cancel at least one out of every ten orders because of inaccurate inventory data.

The solution? Real-time inventory synchronization across all your channels, suppliers, and partner stores.

Instead of frantically updating stock levels in five different places every time you make a sale, automated syncing does the heavy lifting for you. When a product sells on any channel, inventory levels update instantly everywhere else – no more overselling, no more disappointed customers.

How it works:

• A customer buys your last item on your UK store → Stock automatically updates to zero on US, Australia, and your wholesale stores
• Your supplier restocks → New quantities flow to all your sales channels immediately
• Your partner store makes a sale → Your shared inventory adjusts in real-time

Apps like Syncio make this seamless, connecting your store with your suppliers' websites, partner stores, and/or expansion stores in just a few clicks – turning what used to be a manual nightmare into an automated system that works while you sleep.

Implement safety stock buffers 

Give yourself a safety net by holding back a small reserve of inventory units. Instead of selling 100% of your stock, keep 2-5 units as a buffer to protect against warehouse miscounts, system delays during high-traffic periods, or technical hiccups.

How it works:

• You have 40 shirts in stock
• Set a 5-unit buffer
• Your store shows 35 available for sale
• The 5 reserved units protect against overselling

Shopify doesn't have a native safety stock setting, but Syncio's Synced Stock Buffer feature makes this automatic. Just toggle it on in Product Settings → Variant tab, set your buffer amount, and it will apply across all your synced products within 24 hours.

Pro tip: It’s best to start with a 2-3 unit buffer for most products.

Prioritise inventory based on the item's value/popularity

When you’re implementing these stock buffers and management systems, put particular emphasis on products with a high price tag or historically high sales. By focusing on these items, you’re protecting your most valuable assets and minimizing potential loss. 

Set up low stock alerts 

To be automatically alerted when inventory falls below a certain level you set, use apps like Shopify flow or LSA. Find more information on how to use Shopify flow here. 

Implement a virtual waiting room to control flow

Manage web traffic for popular products by implementing a virtual waiting room. This will ensure only one customer is purchasing at a time and avoid system crashes that lead to overselling.

Invest in accurate forecasting/demand planning 

The best indication of future sales is past performance. Look at historical sales data, industry trends and seasonality to predict your risk of overselling. Here’s a handy ChatGPT prompt you can copy and paste for better insights: 

You are an experienced e-commerce inventory planner. I run an online store called [Your Store Name]. I want to forecast demand to avoid overselling, especially around key sales periods. I’ll provide you with historical sales data and upcoming marketing events, and I want you to help me:
- Analyze sales velocity (units sold per day/week/month).
- Identify seasonal trends or spikes in demand.
- Project inventory needs for the next [insert timeframe: e.g., 3 months, 6 months].
- Recommend reorder points and safety stock levels.
- Show the results in a simple table or Google Sheets–friendly format.

Here’s the data:
Historical sales: [Paste units sold per SKU per month or week].
Marketing calendar: [List upcoming campaigns, sales events, or promotions].
Supplier lead times: [e.g., 3 weeks from order to delivery].
Preferred safety stock buffer: [e.g., 5 units or 10%].

Please generate:
- A demand forecast for each SKU.
- Suggested reorder points based on lead times.
- Recommended safety stock levels.
- Notes on any products at risk of overselling.

‍

Stop overselling before it starts

Overselling doesn't have to be an inevitable part of running your Shopify store. By letting automation do the work for you, you can avoid all the administrative headaches, poor reviews and lost sales that come with overselling. 

If you’re keen to never worry about overselling again, try Syncio for free. Your customers (and your stress levels) will thank you.

‍