— Free UK Property Tool —

Property Flip Profit Calculator

Full deal analysis in one tool — gross and net profit, ROI on cash, annualised return, 70% rule check, break-even ARV. Includes bridging finance, refurb contingency, SDLT additional property surcharge, and CGT vs Income Tax modelling. Compare your flip returns against a BTL on the same property.

70% Rule Check Bridging Finance Refurb Contingency Annualised ROI CGT vs Income Tax Break-Even ARV

Deal Details

Purchase
Purchase Price£
£
Cash purchase
No bridging finance — uses 100% equity
Purchase Legal Feescurrent quote
£
Survey / Valuationcurrent quote
£
Capital-improvement share of refurbexclude repairs and decorating for CGT
%
Higher SDLT rates apply
Usually companies and individuals who will own another dwelling at completion
Bridging LTV% of purchase financed
%
Bridging Rate (annual)use a current facility quote
%
Bridging Feesarrangement, exit and admin estimate
%
Refurbishment
Refurb Budgetkitchen, bathroom, decoration
£
Contingency% of refurb — stress-test this input
%
Holding Periodpurchase to sale completion
mo
Monthly Holding Costscouncil tax, utilities, insurance and security
£
Sale
After-Repair Value (ARV)estimated final sale price
£
Selling Agent Fee% of sale, +VAT
%
Solicitor (Sale)current quote
£
EPC + Other Selling Costs£
£
Tax
Effective Income Tax Ratesimplified trading-income rate
%
Effective Property CGT Ratesimplified blended rate for capital-disposal mode
%
Model as a capital disposal
Use only where CGT treatment genuinely applies; hold length alone does not decide this.
How this calculator works — formulas & sources
The 70% Rule
Max Purchase Price = (ARV × 70%) − Refurbishment Costs
ARV = After-Repair Value (estimated post-renovation sale price)
The 70% rule is a screening heuristic, not a UK lending or valuation standard. The 30% buffer is intended to cover tax, finance, legal fees, selling costs, uncertainty and profit. Always model the full cashflow rather than treating the rule as a pass/fail investment recommendation. Stamp Duty (SDLT) Explained · HMO vs BTL
SDLT on Flip Purchase
When higher residential rates apply: 5% on £0–125k · 7% on £125–250k · 10% on £250–925k, with higher bands above
Companies generally pay the higher residential rates. For individuals, the higher rates depend on ownership and replacement-main-residence conditions at completion; a first property is not automatically charged at the higher rates merely because it will be flipped. This simplified tool excludes linked, mixed-use and unusual corporate transactions. Check the full SDLT calculator. Stamp Duty (SDLT) Explained
Bridging Finance Cost
Bridging Cost = Loan × Monthly Rate × Hold Period (months)
Loan = Purchase Price − Deposit
Arrangement Fee = Loan × Entered Arrangement %
The calculator uses simple interest on the financed amount plus the single entered fee percentage. It does not model retained interest, stepped rates, minimum terms or interest on rolled-up fees. Reconcile it to the facility illustration. Rent vs Buy Explained
Net Profit
Gross Profit = Sale Price − Purchase Price − Refurb − All Costs
All Costs = SDLT + Bridging + Legal (buy) + Legal (sell) + Agent Fee
Net Profit = Gross Profit − Tax
The entered contingency is added to the refurbishment budget. Agent commission plus VAT applies to the full entered sale price. Purchase, sale and monthly holding costs use the editable inputs. HMO vs BTL · Rent vs Buy Explained
CGT vs Income Tax
Capital-disposal mode: (Simplified Gain − £3,000 exemption) × Entered Effective CGT Rate
Trading mode: Modelled Cash Profit × Entered Income Tax Rate
HMRC determines classification from the facts and original intention, not from a 12-month holding threshold. Property acquired with the intention of resale may be taxed as trading income. In capital-disposal mode this calculator excludes finance and ordinary holding costs from the simplified taxable-gain calculation. Always confirm the treatment and allowable costs with a specialist accountant. Section 24 Explained · HMO vs BTL
Annualised ROI
ROI = Net Profit ÷ Total Cash Invested × 100%
Annualised ROI = (1 + ROI)^(12 ÷ Hold Months) − 1
Total Cash Invested = Deposit + SDLT + Legal + Refurb
Annualisation converts the modelled return to a 12-month equivalent. It is highly sensitive to the holding-period input and does not imply repeatability, liquidity or equivalent risk. HMO vs BTL · Rent vs Buy Explained
Official sources: GOV.UK residential SDLT rates · GOV.UK Capital Gains Tax rates · Finance Act 2003, Part 4 (SDLT) · HMRC land-trading guidance (BIM60000)

Deal Results

Net Profit (after tax)
—
—
⬤ Calculating…
Returns
ROI on Cash
—
return on deposit
Annualised ROI
—
scaled to 12 months
Profit Margin
—
% of ARV
Cash Invested
—
total deployed
70% Rule Check
70% Rule —
—
Cost Breakdown
Break-Even Analysis
Break-Even ARV—
Margin of Safety—

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How it works

What makes a flip work

Property flipping is profitable only when the numbers work before you buy. Here's what each metric tells you and where flips usually fail.

THE 70% RULE
The investor’s safety net

The 30% buffer is a screening convention intended to leave room for SDLT, finance, professional fees, holding costs, uncertainty and profit. It is not a valuation rule or recommendation. Model the full cashflow and stress-test the ARV, costs and timeline rather than changing the percentage by investor type. Stamp Duty (SDLT) Explained · HMO vs BTL

INCOME TAX vs CGT
HMRC chooses, not you

Tax treatment follows the facts. Acquisition intent, transaction history, work done, finance, organisation and holding period can all be relevant, but no single badge or fixed holding period decides the result. Property acquired for resale may produce trading income; a capital disposal can instead fall within CGT. The toggle compares simplified outcomes and does not classify the transaction. HMRC badges-of-trade guidance. Section 24 Explained · HMO vs BTL

BRIDGING FINANCE
The hidden profit killer

Bridging pricing, retained interest, arrangement fees and exit fees vary by lender and product. Enter the quoted annual rate and total fee percentage for the specific facility. The model keeps those finance costs separate from CGT deductions because loan interest is not normally deductible when calculating a capital gain. Rent vs Buy Explained · Section 24 Explained

SDLT SURCHARGE
5% on the entire purchase

Higher residential SDLT rates depend on the buyer and transaction, including whether completion leaves an individual owning more than one dwelling. Companies usually pay the higher rates on residential purchases. Verify replacement-home and other special rules before selecting the toggle. Stamp Duty (SDLT) Explained

REFURB CONTINGENCY
Make uncertainty visible

The contingency input adds a percentage to the entered refurbishment budget. Set it from the survey, specification, contractor quotes and unresolved risks, then stress-test higher costs and a longer programme. A generic percentage cannot replace investigation of structural, services, damp, access and planning risks. HMO vs BTL

ANNUALISED ROI
The honest comparison metric

Annualised ROI compounds the modelled return to a 12-month equivalent for comparison. It does not mean the same result can be repeated, and it excludes differences in liquidity and execution risk. Use it alongside absolute profit, cash required and downside scenarios. HMO vs BTL · Rent vs Buy Explained

FAQ

Common questions

What is the 70% rule in property flipping?
The 70% rule is a screening convention: 70% of the entered After-Repair Value minus refurbishment cost. It is not a valuation standard, lending rule or recommended offer. Its buffer does not calculate the deal’s actual SDLT, finance, professional fees, holding costs, tax or risk, so use the full cashflow and stress-test every material input. Stamp Duty (SDLT) Explained · HMO vs BTL
Will HMRC tax my flip as Income Tax or Capital Gains Tax?
HMRC determines the treatment from the overall character of the transaction. Acquisition intent, previous transactions, funding, organisation and holding period are relevant, but no single factor or fixed holding period decides the result. Property acquired for resale may be trading income; a capital disposal can instead fall within CGT. The calculator therefore lets you compare treatments but cannot classify the transaction. Review HMRC's badges-of-trade guidance and obtain tax advice for the facts of the deal. Section 24 Explained · HMO vs BTL
How much SDLT do I pay on a flip purchase?
The higher residential SDLT rates usually apply when the transaction leaves the buyer owning more than one residential property, and companies usually pay them on residential acquisitions. Replacement-main-residence, low-value and other transaction-specific rules can change the result. Select the higher-rate toggle only when those conditions apply, and verify the purchase with GOV.UK's current guidance. Stamp Duty (SDLT) Explained · Rent vs Buy Explained
What does "annualised ROI" actually mean?
Annualised ROI compounds the modelled deal return to a 12-month equivalent so scenarios with different timelines can be compared. It is highly sensitive to the holding-period input and does not show liquidity, execution risk, delays or the ability to repeat a deal. Treat it as a comparison output, not a target or forecast. HMO vs BTL
How accurate is the bridging finance calculation?
The calculator applies simple interest to the financed amount for the entered holding period, then adds the single fee percentage you enter. It does not reproduce retained-interest calculations, minimum terms, stepped rates, valuation and legal charges, exit conditions or interest charged on rolled-up fees. Reconcile the output to the lender’s written illustration and model delays before committing. Rent vs Buy Explained
What's a realistic profit margin on a flip?
There is no universal safe profit margin. Required margin depends on refurbishment uncertainty, finance, sale-price sensitivity, tax treatment, time and the return required for the risk taken. Use the editable inputs and stress-test lower sale prices, higher costs and a longer hold; the coloured states describe the current scenario and are not investment recommendations. HMO vs BTL · Rent vs Buy Explained