When a buyer holds two quotes — one for a light collaborative arm, one for a heavy 6-axis industrial arm — comparing the prices directly is meaningless, because they do different jobs at different scales. The fix is a normalized metric. Cost per kilogram of rated payload strips out brand and form factor and asks one question: how many dollars am I paying per kilogram of lifting capability? This guide explains the method, shows how rated payload differs across real product classes, and is honest about where the metric breaks down.
The formula
Cost per payload kg = unit price ÷ rated payload (kg). Use the same price basis on both sides of any comparison — ideally FOB or landed, never one EXW figure against one DDP figure — and use the manufacturer's rated payload (the continuous-duty figure on the datasheet), not a peak or burst number. The metric is most meaningful within a class (6-axis vs 6-axis); across classes it is a sanity check, not a verdict, because a cobot's price reflects safety-rated collaborative features a bare industrial arm does not carry.
Rated payload spans a wide range — which is the whole point
Rated payload is published on every reputable manufacturer's datasheet, so the denominator of the metric is verifiable even when prices are quote-confidential. The span is large. Universal Robots' collaborative e-Series and UR-series arms range from roughly 3 kg up to 35 kg of rated payload across the line, "up to 35 kg" for the heaviest current model (Universal Robots product pages, universal-robots.com). At the industrial end, Estun — a manufacturer named in the robosino catalog — lists 6-axis arms such as the iER220 series whose model designation reflects a 220 kg-class payload (robosino.com / Estun). That is roughly a 70-fold span in capacity, which is exactly why sticker price alone tells you nothing.
| Class | Example model family | Rated payload (published) | Source |
|---|---|---|---|
| Light cobot | UR e-Series (e.g. UR3e) | ~3 kg class | universal-robots.com |
| Mid cobot | UR-series heavier models | up to 35 kg | universal-robots.com |
| Heavy 6-axis industrial | Estun iER220 series | 220 kg class | robosino.com / Estun |
We deliberately do not fill in a price column above: unit pricing for these models is quote-based and supplier-confidential, and fabricating a number would defeat the entire purpose of a citable index. The payload figures are real and datasheet-published; the prices are the part you supply from your own quotes.
Worked method (you bring the prices)
Say you receive two FOB quotes and want to compare them on capability rather than on headline cost. Drop each into the formula:
| Step | Quote A (light cobot) | Quote B (heavy 6-axis) |
|---|---|---|
| Rated payload (datasheet) | e.g. 10 kg | e.g. 220 kg |
| Your FOB quote | (from supplier) | (from supplier) |
| $/payload-kg | FOB ÷ 10 | FOB ÷ 220 |
| What it tells you | Premium for collaborative safety + small footprint | Raw lifting economics at scale |
You will almost always find the heavy industrial arm has a far lower $/payload-kg — heavy arms are cheaper per kilogram lifted. That is not a reason to buy one; it is a reason to compare like with like. A cobot's higher $/payload-kg buys force-limited safety, easy redeployment and no safety cage, which a bare industrial arm cannot offer. Use the metric within a class to spot an overpriced quote, and across classes only to understand what you are paying the premium for.
Where the metric breaks down
Payload is one dimension; reach, repeatability, cycle time, safety rating and software ecosystem are others that $/payload-kg ignores entirely. A long-reach arm at the same payload costs more for the reach, not the lift. And a robot that lifts more than your application needs is not a better deal at a lower $/kg — it is over-spec capital. Per the China Robot Price Index, Q3 2026, we treat $/payload-kg as a yardstick to flag outliers in your own quote set, not as a ranking that decides the purchase.
FAQ
What is cost per payload kilogram?
It is a normalization: unit price divided by the robot's rated payload in kilograms. It lets you compare arms of very different sizes on one axis — for example a ~3 kg cobot against a 220 kg-class industrial arm (payload spans published by Universal Robots and Estun). It is a method to apply to your own quotes, not a headline Index figure this quarter.
Why don't you publish a single $/payload-kg number?
Because the verified sample is still being expanded, and the China Robot Price Index withholds a figure rather than ship a fragile one. The payload denominators are datasheet-real; the prices are quote-confidential, so the responsible answer is to give you the method and let you apply it to your actual quotes.
Do heavy industrial arms have a lower cost per payload kg?
Almost always, yes — raw lifting capacity is cheaper per kilogram at the heavy end. That does not make a heavy arm the better buy; a cobot's higher $/payload-kg pays for force-limited safety, no cage, and easy redeployment that a bare industrial arm does not offer.
What does the metric miss?
Reach, repeatability, cycle time, safety rating and software ecosystem — none of which appear in $/payload-kg. Use it to spot an overpriced quote within a class, not to rank robots across classes.
Payload figures are from manufacturer datasheets (Universal Robots; Estun via robosino.com), dated to access 2026-06-22. The $/payload-kg method is framed by the Robot Sourcing Index; no per-model price is published. Reference information only, not legal, customs or investment advice.