What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
The key distinction is the price’s basis. To add VAT to a net price, multiply by 1 + r; to remove VAT from a gross price, divide by 1 + r. To find the VAT already contained in a gross price, use G × r ÷ (1 + r)—not G × r. Here, r is the VAT rate written as a decimal, N is the VAT-exclusive net amount and G is the VAT-inclusive gross amount.
How to calculate prices with and without VAT
The formulas for a single rate are:
- Net to gross:
G = N × (1 + r) - Gross to net:
N = G ÷ (1 + r) - VAT contained in gross:
VAT = G × r ÷ (1 + r)
HM Revenue & Customs says: “To work out a price that includes the standard rate of VAT (Value Added Tax) (currently 20%), multiply the price excluding VAT (Value Added Tax) by 1.2.” The 20% standard rate and 5% reduced rate are those stated on HMRC’s UK guidance page when accessed in 2026; rates and applicable tax treatment depend on the jurisdiction, supply and date. HMRC: Charging VAT
As an Amazon Associate I earn from qualifying purchases.
Example: adding VAT to a net price
For a £60 net price at 20%, r = 0.20, so £60 × 1.20 = £72 gross. The VAT is £12.
Example: reversing VAT from a gross price
For a £180 gross price at 20%, £180 ÷ 1.20 = £150 net, leaving £30 VAT. HMRC’s guidance also demonstrates reversing a 5% charge by dividing the gross price by 1.05.
#1 Best Overall
- Profitability calculations; cash flow function Calculates NPV and IRR for uneven cash flows
- Time-value-of-money and Amortization keys solve problems including: pension calculations, loans, mortgages, etc.
- Ideal calculator for students, managers and statisticians
- Built-in functionality : List-based one- and two-variable statistics with four regression options: linear, logarithmic, exponential and power
- The BA II Plus calculator is approved for use on the following professional exams: Chartered Financial Analyst exam. GARP Financial Risk Manager (FRM) exam. Certified Management Accountants exam
How much VAT is included in a price?
For a single-rate sale, the VAT portion of a gross amount is the VAT fraction r ÷ (1 + r). At 20%, that fraction is 0.20 ÷ 1.20 = 1/6. Thus, in £120 gross, VAT is £20 and the net amount is £100.
Multiplying £120 by 20% gives £24, which is wrong as an extraction: that calculates 20% of the gross total, even though the rate is applied to the net amount. HMRC Notice 700 describes using the VAT fraction to calculate VAT included in a price. HMRC: VAT guide (VAT Notice 700)
Rank #2
- HP 10BII+ FOR STUDENTS & PROFESSIONALS – This HP calculator is built for business, finance, accounting, and statistics courses. Perfect for learners and professionals who need to solve common financial problems quickly without memorizing formulas or relying on spreadsheets.
- 100+ FUNCTIONS FOR REAL WORLD MATH – Quickly solve time value of money, interest rates, loan payments, NPV, IRR, cash flows, and more. The 10bII+ also includes probability distributions for statistics courses—a feature not often found in financial calculators.
- ALGORITHMIC INPUT WITH DEDICATED KEYS – This high-school/college calculator uses algebraic and chain logic with minimal keystrokes. Layout appears the same as standard calculators for easy learning. Dedicated keys give quick access to commonly used financial and statistical functions
- APPROVED FOR MAJOR EXAMS – The HP 10bII+ algebra calculator is permitted for use on SAT, PSAT/NMSQT, and AP tests. An ideal statistics calculator and business calculator for school finance and accounting students preparing for class, coursework, or standardized exams.
- INCLUDES TRAVEL CASE, CLEANING CLOTH & BATTERIES– Slim, durable, and easy to keep on hand or store in a backpack or locker. Includes a protective case, cleaning cloth, and batteries so it’s ready out of the box. Large screen with clear contrast (non-backlit) is easy to read during exams or lectures.
Why price basis belongs in the data model
A bare amount such as 100 does not tell checkout software whether it means net or gross. The system also needs to know the currency, applicable tax treatment and rounding policy. Treating the basis as an explicit part of the value is a sound engineering practice inferred from the formulas; it is not an architecture requirement prescribed by HMRC.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitches- Use explicit names or types, such as
netAmountandgrossAmount, rather than an ambiguousprice. - Keep the numeric amount and its basis separate from formatted display text; do not infer tax treatment by parsing a currency string.
- Test both directions: adding a rate to net and extracting net and VAT from gross.
- For a 20% test, verify that £100 net becomes £120 gross, and that £120 gross resolves to £100 net plus £20 VAT—not £24 VAT.
What should checkout display: VAT-inclusive or exclusive?
Display requirements are not determined by the arithmetic alone. For the UK, HMRC says VAT is included in shop prices and that advertising aimed at the general public shows VAT-inclusive amounts. Listings aimed at both businesses and consumers might show both prices, while business-only listings do not usually include VAT. These are UK guidance points, not universal rules for every country or transaction. HMRC: Where you see VAT
Rank #3
- Solves time-value-of-money calculations such as annuities, mortgages, leases, savings, and more
- Performs cash-flow analysis for up to 32 uneven cash flows with up to 4-digit frequencies
- Calculates various financial functions: Net Future Value Net present Value Modified Internal Rate of Return Internal Rate of Return Modified Duration Payback Discounted Payback
- The Texas Instruments BAII Plus Professional features an Automatic Power Down (APD) function for extended battery life
- Prompted display guides you through financial calculations showing current variable and label. Ten-digit display
A display label is not a substitute for the applicable law or the contract. HMRC’s guidance on mistakes in charging VAT explains that the appropriate charging basis depends on the precise contract terms between the parties, and that the amount mistakenly charged can affect VAT due, including where a trader intended to quote an exclusive amount. HMRC: VATVAL02400 — mistakes in charging VAT
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to handle mixed VAT rates and rounding
Separate supplies with different VAT liabilities
Do not apply one rate to an entire basket if it contains supplies with different VAT liabilities. HMRC Notice 700 gives examples that allocate a combined amount across standard-rated and zero-rated supplies, then apply the VAT fraction only to the standard-rated portion. The supplies and relevant rules determine the treatment; a single-rate formula cannot decide them.
Rank #4
- Profit margin calculation
- Quick and easy tax calculation
- Square root, sign change, and memory keys
- Attractive metallic design
- 12 digits
Make the rounding policy explicit
The cited HMRC pages establish the core formulas and show that mixed supplies may need apportionment. They do not establish one general rule for rounding per line versus at basket total, or the exact statutory treatment for every UK transaction type. For a production checkout, document how rounding works and verify it for the relevant jurisdiction and transaction against tax-authority rules, the payment provider and the accounting system.
Free tools Windows power users keep installed
One-click scans. No signup required.
Quick Recap
Best Value
- PROFESSIONAL FINANCIAL CALCULATOR : Built-in TVM, IRR, NPV. Engineered for business analysts, real estate investors, accountants, and finance students.
- ADVANCED CASH FLOW & AMORTIZATION : Execute time value of money, break-even analysis, depreciation schedules, and bond pricing. Trusted for professional exam prep", MBA coursework, and banking certifications.
- CATIGA CF-300 : Flip-open hard case with a snap-close design for a secure fit. Compact and portable: designed for daily professional use in office, classroom, or on-site.
- ALL-IN-ONE FOR PROFESSIONALS : From NPV/IRR for real estate analysis to statistical calculations for business analysts. Handles probability, linear regression, and complex financial formulas.
- MORTGAGE, LOAN & INVESTMENT CALCULATOR : Covers bond pricing, loan amortization, investment analysis, and exam-level computations. Your go-to accounting calculator, business calculator, and real estate calculator in one device.
Implementation checks before release
- Confirm which jurisdictions, rates and supply types the checkout supports; do not assume one rate applies to every item.
- Define whether each incoming amount is net or gross and preserve that basis through calculation and display.
- Test single-rate calculations in both directions, including VAT extraction from gross.
- Test mixed-rate baskets and the configured rounding behavior against the applicable rules and downstream systems.
- Ensure invoices and audit records retain enough detail to explain the amount, basis and tax calculation.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
