# Stock-Aware Maximum Rules

> Source: https://primemoq.app/help/rule-types/stock-aware-maximum
> Collection: Rule Types
> Updated: 2026-08-26

Cap a rule against real inventory rather than a number you typed once, reserving stock for other channels and tightening as you sell through.

**Short answer.** Every rule's Conditions card has a Stock-aware maximum card beneath it, called Stock-aware availability on Value and Weight rules. Turning it on caps the rule against current inventory instead of a fixed number. It reserves a keep-back amount for other channels, recalculates within about a minute of a stock change, and on Quantity rules can also set a hard ceiling and decide what happens when stock falls below the rule's own minimum.

## Key takeaways

- Pro plan only, and it appears on every rule regardless of limit type.
- The stricter of your typed maximum and the stock-calculated one is what is enforced.
- Keep back above your actual stock stops the variant selling under this rule entirely.
- Preview always shows your typed number, not the stock-capped one. Test on the storefront.

## Before you start

- Inventory tracking enabled on the variants involved. An untracked variant is skipped.

## What it does

A typed maximum is a guess about stock you had when you typed it. Stock-aware maximum replaces the guess with the number.

The card sits below Conditions on every rule. On a Quantity rule it is called **Stock-aware maximum**, and on a Value or Weight rule it is called **Stock-aware availability**, because the thing it protects there is whether the product can be bought at all rather than how many units.

| Field | Shown for | What it does |
| --- | --- | --- |
| Enable | All limit types | Turns stock awareness on for this rule |
| Keep back | All limit types | Units reserved for other channels before anything is available to this rule |
| Never above | Quantity only | A hard ceiling even when stock is deep |
| If it falls below the minimum | Quantity only | Stop selling, the default, or ignore the minimum |

## How the number is worked out

Prime MOQ sums your tracked inventory across the locations Shopify marks as fulfilling online orders, subtracts **Keep back**, and uses what remains.

- If the result is zero or less, the variant stops selling under this rule. That applies to every limit type, not only Quantity.
- On a Quantity rule, the result becomes the maximum, capped further by Never above if you set one. Whichever is stricter between this and your typed maximum is what enforces.
- On a Value or Weight rule, a healthy stock level leaves your typed maximum alone. Keep back only matters once stock is low enough to threaten it.

![Stock](https://gguwnkfgjlcfliffrfon.supabase.co/storage/v1/object/public/help-media/c8e7568c-stock-aware.png)

_Stock_

The calculation runs on real inventory changes, with roughly a minute of lag, plus a nightly pass as a safety net. The result is written into the same rule data the Shopify Function reads at checkout, so checkout is not making a live inventory lookup on every cart. That is what keeps it fast, and it is also why the lag exists.

## Turn it on

**Set the rule's normal Conditions first,** limit type and bounds, as usual. See [Maximum order quantity](https://primemoq.app/help/rule-types/maximum-order-quantity).

**Scroll to the Stock-aware card and turn it on.**

**Set Keep back** to whatever you want reserved for other channels, or 0 if none.

**On a Quantity rule, optionally set Never above** as a hard ceiling, and choose what happens if the calculated maximum would fall below the rule's own minimum: stop selling, or ignore the minimum.

**Save,** then check a product on your live storefront rather than in Preview.

## Common mistakes

- Keep back at or above your actual stock. The variant stops selling under this rule entirely, for any limit type. Check your real stock before setting it.
- Expecting Preview to show the capped number. Preview always simulates your typed value. The storefront is where the stock-adjusted number appears. See Preview a rule before publishing.
- Expecting instant updates. A sale or a restock takes about a minute to reach the capped maximum.
- A variant that does not track inventory. The feature has nothing to read, so it is skipped and your typed maximum applies unchanged.
- The toggle is on but nothing changes. A store connected before this feature shipped may need to grant Prime MOQ renewed permission to read locations and inventory. Reconnecting the app resolves it, and there is no error message for this case, so it is worth ruling out early.

## FAQ

### Does this replace the maximum I typed in Conditions?

No. The two work together, and whichever is stricter at that moment is what enforces. Your typed maximum stays as the ceiling you never want exceeded even when stock is deep.

### What happens across several warehouse locations?

Stock is summed across the locations Shopify has marked as fulfilling online orders. It is not configured per rule, so changing which locations fulfil online orders in Shopify changes what this feature counts.

### Does keep back work the same way on Value and Weight rules?

The reserve applies to all three limit types. Only Quantity rules also get the Never above ceiling and the below-minimum choice, because both of those concepts are counted in units.

### Is it available on the free plan?

No. Stock-aware maximum and availability are Pro only. On the free plan the card is visible with a lock badge, so you can see what it would do.

### What happens if stock goes negative through overselling?

Tracked inventory below zero is treated as no stock available, which means the variant stops selling under this rule rather than falling back to your typed maximum.

**Best for:** Stores selling limited or fast-moving stock across several channels, who do not want to edit a maximum every time inventory moves.

**Applies to:** Pro plan, Quantity, Value and Weight limit types