Sourcing, procurement & engineering calculators

Build a clean, standard B2B request for quotation or purchase order in the browser and print it or save it as a PDF — no template files or account needed.

Create a standard sales quotation with Incoterms, payment terms, validity, discount, tax and a SAY TOTAL line — print or save as PDF.

Draft a proforma invoice with HS codes, ports, consignee, bank details and payment terms for an L/C, T/T transfer or customs clearance.

List carton numbers, quantities, gross/net weights and dimensions with automatic volume in m³ — the packing list customs and forwarders work from.

Weigh up 3–5 quotes on price, lead time, payment terms and warranty, with a visual price comparison, gross margin at your resale price and weighted scoring that ranks the best-value supplier.

Turn a FOB quote into a landed, tax-inclusive price by adding freight, import duty, VAT and brokerage fees.

Add up BOM line items with quantity, unit price, FX and margin — total cost, per-unit and top spend.

Compare tiered pricing and find out whether buying a higher quantity break is cheaper than your exact order — with the saving spelled out.

Compare full reels against mixing in cut-tape for any quantity — cheapest option, handling fee effect and surplus stock at a glance.

Paste a messy order message and instantly pull out part numbers, quantities and attributes into a clean, copyable table.

Solve cost, selling price, margin and markup from any two values — and see why 25% margin is not 25% markup.

Is 2/10 net 60 worth taking? Convert the discount into an annualised yield, compare with your cost of capital, and see the net saving.

Turn old price, new price and annual volume into your purchase price variance — with a ready-to-paste summary sentence for a year-end report.

Turn a contract clause into the exact deduction: days late, daily rate and cap, plus the final payment figure to notify the supplier.

Reserve the right FX buffer on a foreign-currency order from volatility and payment horizon — compared with your current reserve.

Solve voltage, current, resistance and power from any two known values — with the V-I-R-P formula wheel.

Work out Vout from Vin, R1 and R2, or find the resistor ratio for a target output voltage. Includes divider current and R2 voltage share.

Combine resistors in series or parallel — equivalent resistance, voltage/current shares and the nearest standard E24 value.

Solve loaded voltage dividers, R-2R ladder output and T / pi attenuators.

Compute the RC time constant, charge/discharge voltage at any time, or solve R or C for a target tau.

Find the resonant frequency of an LC circuit from L and C — or solve L or C for a target frequency.

Decode 4, 5 and 6-band through-hole resistor color codes (IEC 60062) — or work backwards from a resistance to its bands.

Decode SMD resistor markings: 3-digit, 4-digit and the EIA-96 two-digit-plus-letter code.

Work backwards from a resistance value to the EIA-96 two-digit-plus-letter code on a 1% SMD resistor.

Decode ceramic SMD capacitor markings — the 3-digit pF code, tolerance letter and voltage code — into a readable value.

Decode the color bands on an inductor into microhenries — military MIL-PRF-15305 style.

Find the resistor and its power rating for any LED from supply voltage, forward voltage and target current.

Design an LED array in series, parallel or matrix: drive resistor, supply current and power.

Design a buck or boost converter: duty cycle, average switch current and the inductor value from ripple spec.

Find the feedback divider for an adjustable buck or boost from target output voltage and Vref.

Estimate LDO power dissipation, junction temperature and dropout voltage from input/output and load.

Check whether a power device needs a heatsink and what sink-to-air resistance holds the junction under its limit.

Work out the heatsink-to-ambient thermal resistance you need from power, junction budget and package.

Add up multiple loads per voltage rail, compute total current and headroom for a supply — and estimate battery life.

Estimate runtime from battery capacity (mAh), average current and duty cycle — for IoT and portable designs.

Estimate MOSFET conduction and switching losses from Rds(on), frequency, gate charge and current.

Capacitor charging time, stored energy and the ripple voltage on a rectified DC rail.

Work out the −3 dB cutoff of an RC low-pass or high-pass filter — or find the R or C for a target frequency.

Design a unity-gain Sallen-Key 2nd-order filter: fc, Q, Butterworth/Bessel/Chebyshev response, equal-R or equal-C.

Compute 555 astable frequency, period, duty cycle and high/low times from R1, R2 and C — instant, mobile friendly.

Find the load capacitors for a crystal from its CL spec and PCB stray capacitance.

Compute the closed-loop gain of inverting, non-inverting and differential op-amp circuits from the resistor values.

Design a stable NPN transistor bias network: find R1, R2 and the operating point (Ic, Vce).

Reference table of logic family input/output thresholds (TTL, CMOS, LVCMOS, RS-485, LVDS) plus a driver-to-receiver compatibility check.

Estimate IPC-2221 PCB trace width in mil and mm from current, copper weight and temperature rise — external or internal layer.

Estimate PCB trace resistance, voltage drop and loss from length, width and copper weight (IPC-2221).

Compute microstrip trace impedance, capacitance and delay from width, height and εr (IPC-2141).

Convert a value between binary, octal, decimal and hexadecimal, with an ASCII character view.

Convert baud rate to bit time, byte time (8N1) and throughput — or solve the baud rate for a target byte rate.

Convert between dBm, watts and volts in a 50 Ω system, with dBV / dBu references and the linear power ratio.