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Ohm's Law Calculator

Enter any two values to calculate the rest — voltage, current, resistance, and power.

Fill in any two fields — the other two calculate automatically.

V = I × R, and P = V × I. Given any two known values, the rest follow from these two formulas.

Resistor Color Code Calculator

Calculate resistor value from color bands.

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Amortization Schedule Calculator

Month-by-month loan schedule with interest, principal and balance. Add extra payments.

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VAT & GST Calculator

Add VAT or GST to a price, or remove it from a tax-inclusive total.

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APR Calculator

Find the true annual percentage rate of a loan once fees are included.

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Marketplace Fee Calculator

Fees, payout and profit on eBay, Amazon, Etsy, PayPal or Stripe sales, plus the price for your margin.

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Payment Processing Fee Calculator

Work out a card processor's fee and the net amount you'll receive, with editable Stripe/PayPal UK example rates.

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