KarobarKit
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E-commerce · Local-first · Beta

Marketplace Margin Calculator

Estimate per-order marketplace contribution after platform, shipping, payment, return and tax costs.

Instant result•No account•Inputs stay in your browser
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Trust record

Check the method before you rely on the result

Tier C · Runs locally in this browser
Method
Selling price less user-supplied cost and fee assumptions, with percentage fees applied to selling price.
Contribution = selling price − product − platform fee − shipping − payment fee − return − tax cost
Sources
1 reviewed reference
Open the source register
Effective period
Formula-based; no statutory effective period
Last verified
9 August 2026
Review every 365 days
Reviewer status
Product and domain review: specialist approval not required
Privacy
Scenario inputs and results stay in this browser. Values are not sent to analytics, a backend, a URL or a log. They are not saved by default; an explicit related-tool transfer is kept only in this tab until it closes or you replace it.
Important limitations
  • No marketplace schedule is scraped or guaranteed.
  • Fees, returns, taxes and fulfilment rules vary by vendor, category and date.

Read all limitationsReport an error

Browse E-commerce · Methodology · Sources

A quick guide

Use the number with context

The answer is only useful when you know what it includes and what it leaves out.

How to use it

  1. Enter selling price using the same period and unit as the other inputs.
  2. Enter product cost using the same period and unit as the other inputs.
  3. Enter platform fee using the same period and unit as the other inputs.
  4. Enter shipping cost using the same period and unit as the other inputs.
  5. Enter payment fee using the same period and unit as the other inputs.
  6. Enter return allowance using the same period and unit as the other inputs.
  7. Enter tax cost using the same period and unit as the other inputs.

Formula

Contribution = selling price − product − platform fee − shipping − payment fee − return − tax cost

This is a vendor-neutral estimate; actual marketplace schedules and settlements must be checked separately.

Make it concrete

Worked example

A ₹1,500 order with ₹600 product cost and the displayed fee assumptions produces a positive contribution margin.

Boundaries

What this tool does not assume

Limitations

  • No marketplace schedule is scraped or guaranteed.
  • Fees, returns, taxes and fulfilment rules vary by vendor, category and date.

Edge cases

  • Percentage fees are limited to 0–100%.
  • Negative contribution is shown as a negative margin.

Last reviewed 9 August 2026 · Formula version 1.0

Method & sources

How this result is grounded

The formula is deterministic and runs in your browser. Read the reference below for the method used by this tool.

  • Business economics methodology v1

    KarobarKit controlled methodology · authoritative reference · Checked 9 August 2026

    Supports: business economics formulas · rounding and scope limitations · estimate-only language

Questions

Frequently asked

Does this know Amazon or Flipkart fees?

No. Enter the fee assumptions you want to model. Vendor-specific schedules are planned for a later phase.

Is this profit after tax?

Only the user-supplied tax cost is included; no tax classification or filing result is determined.

Keep going

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Source register checked 9 August 2026.