Where to set a free shipping threshold, and what it costs when you are wrong
Short answer: a free-shipping minimum earns money from three things and loses it on one. It earns from carts topped up to reach it, from buyers who no longer abandon at checkout, and from the fee you stop having to explain. It loses on the shipping you now pay for orders that would have reached the minimum anyway.
The arithmetic
Waived shipping costs the fee you would have collected on every order at or above the minimum.
A top-up earns your margin on the extra merchandise needed to reach the minimum, and costs the fee that cart would have paid.
Recovered buyers earn a whole order's contribution each; how many there are is the number nobody knows without testing.
Why the answer is a range, not a number
Past orders show you the first part exactly and say nothing about the last two. The optimizer therefore sweeps every round threshold, lets you set the top-up rate and the checkout drop-off, prints the drop-off at which each threshold breaks even, and picks a safe threshold: the one that is never far behind the best choice across a grid of both guesses.
Measure and test
Export orders for the last month or two and keep subtotal and shipping cost.
Paste them into the optimizer, or run node cli.mjs analyze orders.csv --current 75.
Read the break-even drop-off beside each threshold and ask whether it is plausible for your store.
Change the minimum for two or three weeks and compare average order value and conversion rate before keeping it.
Questions
Where should a free shipping threshold sit?
A common starting point is 15 to 30 percent above your average order value, so most shoppers are within reach of it but not already past it. The tool tests every round number against your own orders instead of relying on a rule of thumb.
Does free shipping over a minimum actually raise order value?
It can, when enough shoppers just under the minimum add an item to reach it. Whether that pays depends on your margin and on how much shipping you waive on orders that would have reached it anyway. The tool reports the checkout drop-off at which each minimum breaks even.
What if my shipping cost varies a lot by order?
Include a shipping cost per order. Heavy or distant orders that clear the threshold are the expensive ones to waive, and the tool uses each order's own cost when it has one.