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Fast, free, focused calculators — from take-home pay to bottlenecks and biology scores. Honest numbers, no fluff, no friction.

Latest from the lab

New calculators & tools, hand-picked.

Engine & Horsepower June 8, 2026

Calculate fuel injector duty cycle from horsepower, injector size, injector count, and BSFC. Check whether your injectors are safe or too small.

Engine & Horsepower June 8, 2026

Estimate fuel injector size in lb/hr and cc/min from horsepower, BSFC, injector count, and duty cycle.

Budget calculator May 28, 2026

Estimate the take-home impact of pension salary sacrifice, including Income Tax and employee NI savings.

Budget calculator May 28, 2026

Estimate UK student loan repayments across Plan 1, Plan 2, Plan 4, Plan 5 and Postgraduate loans using current thresholds.

Budget calculator May 27, 2026

A plain-English guide to who can claim UK Marriage Allowance, when it helps, when it does not, and how much it can save.

Budget calculator May 27, 2026

Compare the UK trading allowance with actual expenses and learn which route may reduce taxable side-hustle profit more.

Budget calculator May 27, 2026

Inside and outside IR35 change tax route, expenses, pension strategy, risk, and how much of a contractor day rate reaches your bank account.

Try our most-used calculators — UK take-home pay, budget planning, and more.