Building a Metal Trade-In Pricing App with Power Apps

A practical small business solution—and a reusable framework for pricing and estimation apps.

Overview

Small businesses often rely on manual calculations or spreadsheets—especially in industries like jewelry, where pricing depends on fluctuating commodity values and material purity.

In this scenario, a boutique jewelry retailer required a simple and reliable way to calculate trade-in values for precious metals based on:

Metal type (Gold, Silver, Platinum)
Purity (e.g., 24K, 18K, Sterling)
Weight in pennyweights (DWT)
Separate pricing for cash vs. store credit

The solution was a lightweight Power Apps calculator backed by structured data in Microsoft Lists, enabling real-time, consistent pricing with minimal overhead.

Architecture and Design

The solution was built using a clean separation of responsibilities:

Microsoft Lists – Data storage and pricing variables
Power Apps – User interface and interaction layer
Power Fx logic – Calculation engine

This approach allows pricing updates without modifying the app itself.

Data Model

Metals Pricing Variables

This list defines pricing rules at the metal level:

Price per Troy Ounce
Cash Trade-In Percentage
Store Credit Percentage

This enables non-technical staff to adjust pricing, margins, and trade-in policies without app changes.

Metal Purity Reference List

A second list maps purity values (e.g., 18K = 75%) and associates them to the correct metal category.

This structure ensures clean filtering and accurate calculations while keeping the data normalized.

User Experience Flow

Select Metal Type
Select Purity
Enter Weight (DWT)

The application then calculates:

💵 Cash Trade-In Value
🏷️ Store Credit Value

Dynamic Filtering Example

Filter('Metals Pricing List #1', MetalCategory = ddMetalCat.SelectedText.Value)

This ensures only relevant purity options are displayed, reducing user error and improving usability.

Calculation Logic

The pricing model follows a simple but effective formula:

Price Per DWT = Price Per Troy Ounce / 20
Final Value = DWT × Price Per DWT × Purity × Trade Percentage

Cash Example:

Value(DWT) * PricePerDWT * Purity * CashPercent

Store Credit Example:

Value(DWT) * PricePerDWT * Purity * StoreCreditPercent

Interface Design

The app was designed for both tablet and mobile usage with:

Simple dropdown-driven workflow
Real-time pricing display
Centralized input and output fields
Brand-aligned visuals and color scheme

A hidden screen was also used to store calculation variables, reducing clutter and improving performance.

Why This Pattern Works

Separation of data and logic
Minimal maintenance overhead
Highly adaptable to changing pricing models
Usable by non-technical staff

Framework Reuse Opportunities

This pattern extends far beyond jewelry and can be reused across industries:

Retail Trade-In Tools – Electronics or device buyback programs
Construction Estimators – Material and labor calculations
Pawn / Appraisal Systems – Value modeling and loan calculations
Service Pricing Apps – Tiered pricing models
Healthcare Calculators – Parameter-driven cost or dosage tools

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