About ConvertUK & calculation methods
ConvertUK is a free collection of calculators for everyday work, cooking and content creation. Each tool explains its inputs and assumptions so you can check whether the result fits your situation.
Salary and contractor income
The salary calculator estimates 2026/27 Income Tax for England, Wales and Northern Ireland and standard employee National Insurance. It uses annual thresholds, the standard personal allowance and its taper above £100,000. National Insurance on actual payslips is normally calculated per pay period, so irregular pay and rounding can produce differences.
It excludes Scottish Income Tax, pensions, student loans, salary sacrifice, benefits in kind, other income and non-standard tax codes or NI categories. It is an estimate, not a payroll calculation or personal tax advice.
The day-rate calculator multiplies your rate by your expected billable days. Its 220-day default is an example, not an employment entitlement. Gross invoices are not take-home pay or a like-for-like salaried package.
Cooking measurements
The spoon converter uses 15 ml per UK metric tablespoon, 5 ml per teaspoon and 28.4130625 ml per imperial fluid ounce. Use marked measuring spoons: ordinary cutlery has no reliable capacity.
The cups-to-grams calculator multiplies volume by an ingredient density. US cups are 236.588 ml and metric cups are 250 ml. The displayed densities are approximate assumptions; packing, brands and moisture change the weight. Prefer the recipe author's weights and a kitchen scale when precision matters.
Social media presets
The social size guide provides export presets and suggested layout margins, not a guarantee against cropping. Platform interfaces and upload requirements can change. Check the platform preview before publishing.
YouTube's current thumbnail guidance recommends 3840 × 2160 pixels for standard video thumbnails; this preset was checked on 7 September 2026.
Checking a result
Change one input at a time and compare the result with the formula and example table on the tool page. The last-updated date records a content change; it does not mean an independent professional has certified the result.