---
title: "Free charity calculators — Gift Aid, Payroll Giving, Zakat"
description: "Free UK charity calculators: Gift Aid calculator, Payroll Giving vs Gift Aid comparison, Personal Allowance £100k trap optimiser and Zakat calculator."
source: https://www.charitycompare.org.uk/calculators
retrieved: 2026-08-18T00:02:51.072Z
license: "Charity data © Crown copyright, Open Government Licence v3.0"
---

[Donations Gift Aid Calculator What your donation is worth to a charity (25% top-up), what you reclaim at 40% or 45%, and a reverse mode for what you can afford to give. Open the calculator →](https://www.charitycompare.org.uk/gift-aid-calculator)[Compare schemes Payroll Giving vs Gift Aid Side-by-side comparison of both giving schemes at your tax band — charity value, net cost, and the verdict for your situation. Open the calculator →](https://www.charitycompare.org.uk/payroll-giving-calculator)[Higher earners Personal Allowance Optimiser Earn £100k–£125,140? See the exact donation that restores your full Personal Allowance — up to 60% effective relief. Open the calculator →](https://www.charitycompare.org.uk/personal-allowance-gift-aid-calculator)[Faith giving Zakat Calculator Hanafi 2.5% on net assets above the silver nisab. You enter today’s silver price, so the threshold is never a stale figure. Open the calculator →](https://www.charitycompare.org.uk/zakat-calculator)