Documentation

Forthcast is an AI-powered inventory forecasting app for Shopify. It connects to your store, analyzes your sales history, and helps you make smarter decisions about when to reorder, how much safety stock to keep, and which products need attention.

Core capabilities include:

• Demand forecasting at the product variant level
• Automatic reorder point and safety stock calculation
• Purchase order creation and lifecycle tracking (Draft → Sent → Received)
• Lost sales estimation for out-of-stock periods
• Forecast accuracy and bias scoring per product
• Supplier reliability grading
• Multi-location inventory support
• AI Chat for natural language inventory questions

New to Forthcast? Follow the Getting Started guide to get set up in under 10 minutes.

Forthcast analyzes your historical orders to calculate a demand forecast for each product variant. The forecast is expressed as a projected daily sales rate, which is then used to estimate how many units you'll sell over the next 30, 60, or 90 days.

How forecasts are calculated

Forthcast uses a time-series model trained on your store's order history. It detects trends (is demand growing or shrinking?) and seasonality (does demand spike at the same time each year?). Forecasts are recalculated automatically after each new sync with Shopify.

Data requirements

Forecasting works best with at least 30 days of sales history. Products with fewer than 14 days of history will show reduced confidence. The model improves over time as more data is accumulated.

Viewing forecasts

Navigate to Forecasts in the main menu. Use the time horizon selector to switch between 30, 60, and 90-day views. Click any product to see a detailed forecast chart with historical demand and projected demand overlaid.

The Replenishment section shows every product that is at or approaching its reorder point. Forthcast calculates recommended reorder points based on your demand forecast and your supplier's lead time, so you know exactly when to place a new order.

Reorder point

The reorder point is the inventory level at which you should place a new order to avoid a stockout before the next shipment arrives. Forthcast calculates it as: average daily demand × supplier lead time + safety stock.

Safety stock

Safety stock is a buffer against demand spikes and delivery delays. Forthcast calculates it using demand variability and lead time variability at your chosen service level (90%, 95%, or 99%). A higher service level means fewer stockouts but more inventory on hand.

Bulk settings

You can apply reorder point and safety stock settings to multiple products at once by selecting them and using the bulk edit tool. Filter by supplier, collection, or product tag before bulk editing to target the right products.

Create and manage purchase orders directly in Forthcast. Each PO moves through three stages: Draft (being prepared), Sent (order placed with supplier), and Received (goods arrived and Shopify inventory updated).

Creating a purchase order

In the Replenishment section, select the products you want to reorder and click Create Purchase Order. Forthcast pre-fills suggested order quantities. Edit any quantities, set the supplier and expected delivery date, then save the PO as a Draft.

Receiving a purchase order

When goods arrive, open the PO and click Receive. Enter the quantities received for each line item. Forthcast will add those quantities to your Shopify inventory at the selected location. Partial receiving is supported — the PO stays open until all items are received.

Multi-location

Assign each PO to a specific receiving location. Inventory is updated at the correct Shopify location when the PO is received.

Lost sales are the units and revenue you missed because a product was out of stock. Forthcast estimates lost sales by comparing expected demand against actual inventory availability during stockout windows.

Use the Lost Sales page to see which products cost you the most from stockouts — sorted by estimated lost revenue. This helps you prioritize which products need faster reorder cycles or higher safety stock.

Lost sales data also feeds into replenishment prioritization: products with high recent lost sales are flagged for urgent reorder in the Replenishment section.

The Forecast Performance page shows how closely Forthcast's predictions matched your actual sales. Two metrics are displayed per product:

• Accuracy score — the percentage of periods where the forecast fell within an acceptable range of actual demand. Higher is better.
• Bias score — whether the model systematically over-predicts or under-predicts. A positive bias means the forecast tends to be too high; negative means too low.

Use these scores to identify products where the forecast may need attention — either by waiting for more data to accumulate, or by noting that the product has irregular demand patterns.

Add your suppliers in Settings → Suppliers. For each supplier you can set a name, contact email, and average lead time. Forthcast uses lead time to calculate reorder points and safety stock.

Supplier reliability grades

Forthcast automatically grades each supplier (A through D) based on the delivery performance recorded across your purchase orders — on-time rate, average lead time accuracy, and order completion rate. Grades are updated each time a PO is received.

Lower-graded suppliers automatically trigger higher safety stock recommendations, accounting for the added delivery uncertainty.

The Settings section lets you configure global defaults for Forthcast:

• Service level target — Choose 90%, 95%, or 99% to control how conservatively safety stock is calculated.
• Suppliers — Add, edit, and remove suppliers. Set default lead times per supplier.
• Alerts — Configure low stock email notifications — immediate or daily digest.
• Sync settings — Control how frequently Forthcast syncs inventory and orders from Shopify.

The Forthcast AI Chat is available in the bottom-right corner of every page. Ask any inventory question in plain English and get a specific answer based on your store's data.

Example questions

• "Which products are at risk of stocking out in the next 30 days?"
• "What should I reorder from Supplier A?"
• "How accurate were my forecasts last quarter?"
• "Which products have been out of stock the longest?"
• "Show me my most overstocked items."
• "What's my total value of inventory on order?"

The AI Chat understands Forthcast's data model — forecasts, safety stock, purchase orders, supplier grades, and more — and can surface insights you might not immediately find by browsing the app manually.

Have a question not covered in these docs? Check the Frequently Asked Questions page for answers to common questions about setup, billing, data privacy, and more.

Still stuck? Contact our support team — we respond within one business day.