Classroom Supply Budget Calculator

Class size:

{{ integer(params.class_size) }} students

Use the expected enrollment or participant count.

students

Students per group:

For example, use 4 for table kits or lab teams.

students/group

Supply rows:

Open a row to edit it. Reusable stock reduces the order before package rounding.

Item name:

Category:

Priority:

Quantity basis:

{{ quantityLabel(item.basis) }}:

Unit cost:

Reusable stock:

Package size:

units/pack

Discount:

{{ params.discount_mode === 'percent' ? '%' : (params.currency_symbol || '$') }}

Tax rate:

Purchase note:

Discounts are:

Unit prices are:

Required quantities:

Available budget:

Contingency:

{{ decimal(params.contingency_percent, 0) }}%

Currency symbol:

Priority	Item	Need	Stock	Buy	Line total	Funding status	Copy
{{ priorityLabel(row.priority) }}	{{ row.name }}{{ row.note }}	{{ decimal(row.required_quantity, 2) }}	{{ decimal(row.stock, 2) }}	{{ decimal(row.buy_quantity, 2) }}+{{ decimal(row.package_overage_units, 2) }} pack overage	{{ money(row.line_total) }}	{{ fundingLabel(row.cap_status) }}{{ money(row.cumulative_total) }} cumulative

Funding readout

Order review

{{ line }}

Planning boundary

Prices, tax rates, discounts, stock counts, and package sizes are user-entered planning assumptions. Confirm vendor quotes and school purchasing rules before ordering.

Enrollment changes ripple through notebooks, group kits, consumables, and the money needed to buy them. A classroom supply budget connects those needs with a purchase list that vendors can actually fulfill. Existing stock reduces the requirement, while package sizes can push the order back above it.

That sequence matters. Ten students working in groups of four create 2.5 groups mathematically. Whole-item rounding may turn a requirement of five shared items into five units, but a six-unit package means six must be purchased. Rounding too early, subtracting stock after pack rounding, or treating a pack price as a unit price changes the total.

Classroom supply quantity bases
Quantity basis	How demand grows	Typical use
Per student	Enrollment × units per student	Notebooks, folders, individual safety gear
Per group	Enrollment ÷ group size × units per group	Table kits, lab sets, shared manipulatives
Fixed	One classroom total	Cleaning stock, display materials, room equipment

Discount and tax treatment must match the quote. A percentage discount scales with the line subtotal; a flat discount removes a stated amount without making the line negative. Tax-added prices increase the payable total. Tax-inclusive prices already contain tax, so the tax portion can be shown without adding it again.

An available budget is a funding comparison, not a purchasing policy. Priorities help reveal where a cumulative cap is crossed, but required items, approved vendors, tax exemptions, procurement rules, shipping, and lead times still need human review. A contingency cushion covers uncertainty only if its percentage reflects a real planning risk.

How to Use This Tool:

Build the list from current enrollment, current stock, and one consistent set of vendor prices.

Enter Class size and Students per group. Group size matters only for rows whose quantity basis is per group.
Open each supply row and set its name, category, priority, quantity basis, quantity, unit cost, reusable stock, and package size. Add only rows that belong to the same planning currency.
Choose whether discounts are percentages or flat line amounts, whether unit prices include tax, and how required quantities should round. Use fractional quantities only for supplies that can genuinely be bought that way.
Open Advanced to add an available budget, contingency cushion, or currency label. The label changes display only and does not convert exchange rates.
Review the buy quantities, package overage, line totals, and first cap crossing. Confirm quotes, stock counts, package sizes, tax treatment, and required priorities before ordering.

Interpreting Results:

Total budget is the sum of discounted, tax-adjusted supply lines plus contingency. Per student divides that full amount by class size; it does not imply that every line is issued individually.

Stock covered means reusable stock meets the rounded requirement, so the buy quantity is zero.
Package overage is the difference between the net requirement and the next purchasable pack multiple.
When a positive budget cap is entered, lines are accumulated by required, recommended, then optional priority. Within a priority, higher-cost lines come first. The cap status therefore reflects that ordering, not a recommendation to split a vendor order at the displayed row.
A positive budget delta is money left; a negative delta is a funding gap. A zero available budget disables this comparison rather than declaring the plan fully funded.

Technical Details:

Each supply row follows the same order: scale demand, apply the chosen quantity rounding, subtract stock, round again under the same rule, round up to a package multiple, then calculate discounts and tax. Changing that order can change both units and cost.

Formula Core:

For class size C, group size G, row quantity q, stock s, and package size p, raw demand is selected by basis:

\begin{matrix} q_{raw} & = & C q & per student \\ q_{raw} & = & \frac{C}{G} q & per group \\ q_{raw} & = & q & fixed \end{matrix}

Let R be the selected rounding rule: ceiling, nearest whole unit, or no rounding. Required, net, and buy quantities are:

\begin{matrix} q_{req} & = & R (q_{raw}) \\ q_{net} & = & R (max (0, q_{req} - s)) \\ q_{buy} & = & p ⌈ \frac{q_{net}}{p} ⌉ \end{matrix}

When net demand is zero, buy quantity is zero. Otherwise, package rounding always moves up to the next multiple of the whole-number package size.

Price and Budget Rules:

Line subtotal is buy quantity × unit cost. A percentage discount is subtotal × rate ÷ 100. A flat discount is capped at the subtotal. The discounted subtotal cannot fall below zero.

Tax and budget calculation rules
Setting	Tax amount	Line total
Tax added	Discounted subtotal × tax rate	Discounted subtotal + tax
Tax included	Discounted subtotal − discounted subtotal ÷ (1 + tax rate)	Discounted subtotal

In these tax formulas, the percentage is converted to a decimal fraction, so 10% becomes 0.10. Contingency equals total line spend × contingency percentage. Total budget adds contingency to line spend, while budget delta equals available budget minus total budget when a positive cap is present. Calculations retain full numeric precision; displayed money may be rounded for readability.

Funding Order:

Rows are sorted by priority in the order required, recommended, optional. Equal-priority rows sort by line total from largest to smallest, then by name. Contingency is appended as a reserve row. A row is inside the cap when its cumulative total is at or below the available budget, crosses the cap when the total before it was below the budget but the new total is above it, and is unfunded after the cap has already been exceeded.

Accuracy Notes:

Use the result as a purchasing plan, then verify the facts that arithmetic cannot settle.

Prices exclude shipping or fees unless they are represented as supply rows.
Tax rates and exemptions depend on the purchaser, seller, item, and jurisdiction. Match the selected tax mode to the actual quote.
The currency symbol is display-only. Do not mix currencies without converting every line outside the calculator first.
Stock value uses the entered unit cost and is informational; it does not reduce the payable total twice.

Worked Examples:

Shared glue sticks in six-unit packs

Ten students in groups of four need two glue sticks per group. Raw demand is 5, and round-up keeps it at 5. One stick in stock leaves 4 to buy, but a six-unit pack raises the purchase to 6 and creates 2 units of overage. At $1 each with a 10% discount and 10% added tax, the line total is $5.94.