How do you calculate transformer cost per unit?

Multiply the units started by the cost per start, add the tooling and NRE, and divide by the accepted units. 125 starts at 45.00 plus 250 of NRE is 5,875; over 100 accepted units, 58.75 each. That is the Transformer Cost calculator's own example: 100 units at 45 and 80% yield plus 250.

What goes into the cost per start?

Everything one unit started uses, accepted or not: the core or laminations and stacking, the wire and winding labour, and integration (bobbin, insulation, varnish or potting, assembly and test). Keep winding labour in the winding cost only, so it is not counted twice.

How do final rejects change the cost?

Each final reject costs as much as a good unit and has to be paid for by the units that ship. The Reject cost per unit column shows how much: 14 rejects at 94.00 on 60 accepted units add 21.93 to each.

Why is the workbook's yield different from the calculator's?

It is the same thing. The calculator divides by a yield percentage; the workbook counts starts as accepted plus final rejects, and acceptance is accepted / starts. Quantity x rate / yield equals starts x cost per start.

What if early rejects do not reach later stages?

Then they do not use the full cost per start. Cost each stage separately, or enter those rejects at the stage cost they reached.

Does the workbook use macros?

No. It is a plain .xlsx with ordinary formulas, tables and native charts. The Verify sheet re-checks the formulas against fixed test orders and shows Self-check: PASS.

Industry Cost Kits

Transformer Cost Estimator Excel Template

Cost per accepted transformer = (units started × core, winding and integration cost per start + tooling and NRE) ÷ accepted units. Give every order a row and see what its final rejects and NRE add to each good unit, and its margin against your target.

Free, and a plain .xlsx with no macros to enable. A CSV with live formulas and a printed how-to guide come with it.

Overview

This transformer cost estimator is a working Excel workbook for estimators, cost accountants and production engineers at transformer, inductor and magnetics manufacturers. Each order is one row with its accepted and finally rejected units, the core, winding and integration cost of each unit started, any tooling and NRE charged to it, and the quoted price. Every start is costed in full, so the cost per accepted unit carries the rejects and the NRE, and the workbook shows how much of each. It ships with ten orders of a fictional transformer and inductor maker, so every tile and chart is filled in when you open it.

In the example the first order of a potted toroid has 60 accepted units and 14 final rejects at 94.00 a start, plus 3,500 of potting mould and test fixture: 10,456 in all, or 174.27 a unit against a 168.00 price, a 3.7% loss. The rejects add 21.93 to each good unit and the NRE 58.33. The second order of the same design, 120 accepted, 6 rejects and no NRE, costs 98.70 a unit and makes 41%. A repeat 150 VA order after a lamination supplier change rejected 21 of 321 starts against 6 of 256 before, and its margin fell from 27.3% to 24.1%, near the 25% target.

The download is a plain .xlsx with no macros. A CSV with live formulas is also included for other tools; the dashboard, charts and self-check are in the .xlsx.

What this template includes

Setup sheet with your company, currency, target margin and the band that counts as near target
Orders table, one row per order: design, accepted and finally rejected units, core, winding and integration cost per start, tooling and NRE and quoted price, with a Check column
Per order: starts, acceptance, recurring cost per start, order cost, cost of the final rejects, cost per accepted unit with its reject and NRE parts, margin per unit and margin, and a status in words
Dashboard with four tiles (orders, total order cost, cost of final rejects, orders below target margin), cost per accepted unit as a share of price, margin against target, and the order table
Method sheet with every formula, and a Verify sheet that re-checks the formulas against an independent reference and the Transformer Cost calculator (Self-check: PASS)
CSV with live formulas for the Orders table; the dashboard, charts and self-check are in the .xlsx

Suggested use case

Use it to cost completed transformer and inductor orders, to check a quote against what the last order really cost, or to show what a higher reject rate or a one-time NRE does to the margin on a small first order.

How to use it

On Setup, type your company, currency, target margin and the band that counts as near target.
On Orders, give each order a row: accepted and finally rejected units, core, winding and integration cost per start, tooling and NRE, and the quoted price.
Fix anything the Check column names.
Open the Dashboard: orders below target margin, what the final rejects cost, and where each order's price goes.

Frequently Asked Questions

How do you calculate transformer cost per unit?: Multiply the units started by the cost per start, add the tooling and NRE, and divide by the accepted units. 125 starts at 45.00 plus 250 of NRE is 5,875; over 100 accepted units, 58.75 each. That is the Transformer Cost calculator's own example: 100 units at 45 and 80% yield plus 250.
What goes into the cost per start?: Everything one unit started uses, accepted or not: the core or laminations and stacking, the wire and winding labour, and integration (bobbin, insulation, varnish or potting, assembly and test). Keep winding labour in the winding cost only, so it is not counted twice.
How do final rejects change the cost?: Each final reject costs as much as a good unit and has to be paid for by the units that ship. The Reject cost per unit column shows how much: 14 rejects at 94.00 on 60 accepted units add 21.93 to each.
Why is the workbook's yield different from the calculator's?: It is the same thing. The calculator divides by a yield percentage; the workbook counts starts as accepted plus final rejects, and acceptance is accepted / starts. Quantity x rate / yield equals starts x cost per start.
What if early rejects do not reach later stages?: Then they do not use the full cost per start. Cost each stage separately, or enter those rejects at the stage cost they reached.
Does the workbook use macros?: No. It is a plain .xlsx with ordinary formulas, tables and native charts. The Verify sheet re-checks the formulas against fixed test orders and shows Self-check: PASS.