What each of the 45 tools on this site actually computes, and which published document it computes it from. Nothing here is a black box: if you disagree with a result, this page tells you exactly which rule we applied so you can check it against the source yourself.
Each tool below links to its own page, where the same method is shown alongside worked examples and a dated revision history. Our editorial & review policy sets out how often each is re-checked.
Applies IRD APIT Table 01 to monthly regular employment income, then deducts estimated employee EPF from take-home pay.
Primary sources
This is an estimate for regular primary employment income. Payroll treatment can differ for secondary employment, lump-sum payments, non-cash benefits, exemptions, and EPF-eligible earnings.
Uses the standard annuity formula for a fixed-rate, monthly reducing-balance loan.
Primary sources
This is a repayment estimate, not a loan offer. Bank fees, insurance, taxes, variable rates, rounding, and payment dates can change the actual instalment and total cost.
Treats basic salary plus EPF-eligible allowances as the contribution base, deducts employee EPF at 8% from gross pay, and adds employer EPF at 12% and ETF at 3% on top of gross to arrive at total cost to company.
Statutory minimums only. Which allowances are EPF-eligible is a question of fact about your pay structure, and many employers contribute above the minimum. Gratuity, APIT, insurance, and other benefits sit outside this calculation.
Converts billable hours per week into monthly hours at 4.33 weeks per month, adds business expenses to the target take-home to get the amount that must be earned, then divides by monthly hours. The optimal rate grosses that figure up by 30% to provide a 20% margin and a 10% tax provision.
Primary sources
The 20% margin and 10% tax provision are planning defaults chosen for this tool, not rates set by any authority. Your actual tax liability depends on your total income and the current personal income tax bands, and the exchange rate you receive depends on your bank and payment processor.
Calculates a fixed reducing-balance EMI and compares the financed share of the entered vehicle value with the selected CBSL maximum LTV category.
Primary sources
The vehicle category and value accepted by a lender can differ from your input. Lenders may apply a lower LTV and additional credit, income, security, fee, and insurance requirements.
Subtracts entered existing liabilities from the user-selected share of net income, then converts the remaining monthly amount into a reducing-balance loan scenario.
This is not a lender's eligibility model, approval decision, affordability advice, or loan offer. There is no universal DBR or card-limit percentage used by every Sri Lankan lender and product.
Projects annual EPF and ETF balances from statutory minimum contribution rates and the salary-growth and annual-return assumptions entered by the user.
Primary sources
This is an illustrative projection, not an EPF, ETF, or IRD statement. It excludes withdrawals and tax and cannot predict future declared interest or dividends.
Applies simple interest over the tenure, deducts 10% withholding tax from the gross interest, and then either divides the net interest across the months for a monthly-payout deposit or adds it to the principal for a maturity-payout deposit.
Primary sources
An estimate only. Banks quote rates on differing compounding and payout conventions, and this calculator uses simple interest throughout. Confirm the effective annual rate, the payout schedule, and the tax treatment with the institution before committing funds.
Applies the two Section 5 formulas - half a month's wage per completed year for monthly-rated employees, fourteen days' wage per completed year for daily and piece-rated employees - to the last drawn wage, gated by the five-year qualifying period and the fifteen-employee coverage threshold.
Primary sources
This is an estimate of the statutory minimum. A contract, collective agreement, or company policy can provide more, and the treatment of a final part-year varies between employers. Gratuity disputes are handled by the Commissioner of Labour.
Applies the standard reducing-balance annuity formula to the loan amount, and computes stamp duty on the assessed value at 3% of the first Rs. 100,000 and 4% of the remainder. Upfront cash is the down payment plus stamp duty plus the fees entered.
Primary sources
An estimate for a fixed-rate loan. Most Sri Lankan housing loans are variable-rate, so the instalment will move. Stamp duty is charged on the value the Provincial Department of Revenue assesses, which can exceed the price on the deed.
Applies flat interest to the amount financed for the full term, divides the total by the number of instalments, then solves numerically for the reducing-balance rate that would produce the same instalment.
Primary sources
An estimate from the figures entered. Agreements vary in how they treat insurance, registration, and early settlement, and the settlement figure on a flat-rate agreement is set by the contract rather than by recalculating interest.
Multiplies the last drawn consolidated salary by months of service, divides by 480, and caps the result at 90% of salary. Service below 120 months is treated as not qualifying.
Primary sources
The basic monthly pension only. It excludes the commuted gratuity, the Widows' and Orphans' Pension contribution, and cost-of-living allowances granted to pensioners. Entitlement depends on the rules in force at retirement - confirm with the Department of Pensions.
Implements the published Sri Lanka Customs computation formulae exactly: duty and PAL on CIF, cess on CIF plus 10%, excise on CIF plus 15% with duty, cess, and PAL added, and VAT and SSCL on CIF plus 10% with every earlier levy added. Rates are entered by the user because they vary by HS code.
Primary sources
The cascade is applied exactly as published, but the rates for any given HS code change with each budget and by gazette during the year. Confirm current rates with Sri Lanka Customs or a clearing agent before relying on a figure.
Treats the module as a weighted average. It totals the marks already earned against their weights, subtracts that from the target, and divides the shortfall by the weight the final examination carries to give the score required on it.
Arithmetic on the weights you enter. It assumes marks combine as a straight weighted average, which is not true where a module has a separate pass condition on the examination component, applies scaling or moderation, or caps a resit.
Divides lectures attended by lectures conducted. Where you are above the target it solves for how many further sessions can be missed before you drop below it; where you are below, it solves for the run of consecutive sessions needed to climb back.
Primary sources
The 80% threshold is the common requirement, but the rule that binds you is your own faculty's. Some departments set 85%, count practicals separately from lectures, or treat medical leave differently. Check your handbook before relying on a margin.
Solves the credit-weighted GPA equation for the average grade points required across the remaining credits.
Primary sources
The result is a mathematical planning target, not confirmation of a degree class. Your programme may use different thresholds and additional rules.
Calculates a credit-weighted GPA using the selected grade-point mapping and optional degree-class guide.
Primary sources
Sri Lankan universities and faculties do not all use the same grade points, repeat rules, exclusions, or degree-class thresholds. Verify the mapping against your current student handbook.
Standardises each subject as the mark minus the subject mean divided by the subject standard deviation, then averages the three subject z-scores. The mean and standard deviation are entered by the user because the Department of Examinations publishes new figures for every subject, medium, and year.
Primary sources
This calculates the Z-score itself, not an admission outcome. Cut-off marks are published only after the full cohort is processed, and they differ by course, district, and quota. It does not include a cut-off dataset.
Maps each mark to its grade band, counts passes at S and above and credits at C and above, then tests the result against the conditions commonly applied for entry to the Advanced Level.
The eligibility conditions shown are the ones commonly applied, not a decision. The rule binding each cohort is set by circular, and individual A/L streams add their own subject requirements. Confirm with your school.
Uses the three alignment points the awarding bodies fix between the two scales - grade 7 to A, grade 4 to C, and grade 1 to G - and interpolates the rest, marking which is which. Mixed sets are averaged on the numeric scale, with letter grades taking the midpoint of the numbers they span.
No Sri Lankan authority publishes an official equivalence between international grades and local qualifications. The O/L column is indicative only, and every university, professional body, and employer sets its own recognition rule.
Compares the entered Z-score against the UGC minimum Z-score for the chosen district, course by course. The table was transcribed from the UGC PDF by script and verified cell for cell against a second independent extraction: 260 course rows across 25 districts, 6,500 values, all matching. NQC cells are carried as null and never compared as zero.
Primary sources
A cut-off is the outcome of one year's competition, not a threshold carried forward. Meeting a past cut-off does not guarantee selection, and the UGC's own published table is the authority for any decision that matters.
Adds 280 days to the first day of the last menstrual period, adjusted by the difference between your cycle length and a 28-day cycle. When a conception date is entered instead, it works back 14 days to an equivalent LMP before applying the same rule.
An estimated date, not an appointment. Only about one birth in twenty happens on the estimated due date, and a dating ultrasound in the first trimester is more accurate than any calculation from dates. Follow the guidance of your midwife or obstetrician.
Estimates ovulation by subtracting the selected luteal-phase assumption from the next period predicted from the entered average cycle length.
Primary sources
This educational calendar estimate cannot confirm ovulation, fertility, pregnancy, or a medical condition and must not be used as contraception. It has not been individually reviewed by a clinician.
Subtracts the two calendar dates the way a person would by hand, borrowing days from the preceding month and months from the year. Both dates are built from their parts in local time, so the result is the same calendar difference for a reader anywhere in the world.
Calendar arithmetic on the proleptic Gregorian calendar. Where a legal age threshold matters, confirm the rule that applies -- some jurisdictions count an age as attained on the day before the anniversary.
Computes BMI as weight in kilograms divided by height in metres squared, then classifies it against the lower cut-offs the WHO recommends for Asian populations rather than the international thresholds. The healthy weight range is derived from the same 18.5 to 22.9 band.
Primary sources
BMI is a population screening measure, not a diagnosis. It does not distinguish muscle from fat and is unreliable for athletes, pregnant women, children, and older adults. Discuss any concern about your weight with a doctor rather than acting on this number alone.
Calculates basal metabolic rate with Mifflin-St Jeor, multiplies by a standard activity factor for total daily energy expenditure, and adds the calorie change implied by the selected goal at 7,700 kcal per kilogram of body fat.
Primary sources
A population estimate, not a personal prescription. Individual metabolic rates vary by around 10% either way. Anyone who is pregnant, managing a medical condition, or planning a large deficit should speak to a doctor or dietitian first.
Adds four months to the last whole blood donation date, clamping to the end of a shorter month, and checks the entered age and weight against the National Blood Transfusion Service donor criteria.
Primary sources
Only the criteria that can be checked from a date and two numbers. Illness, medication, surgery, tattoos, pregnancy, travel history, and haemoglobin are assessed at the centre on the day and can defer a donor regardless of this result.
Applies IRD APIT Table 01 to monthly regular employment income, then deducts estimated employee EPF from take-home pay.
Primary sources
This is an estimate for regular primary employment income. Payroll treatment can differ for secondary employment, lump-sum payments, non-cash benefits, exemptions, and EPF-eligible earnings.
Applies the selected SSCL rate to the entered base and VAT to the base plus SSCL, or reverses the same calculation for an inclusive total.
Primary sources
SSCL is charged on liable turnover, which varies by activity, and exemptions may apply. Confirm registration, liable-turnover percentage, invoicing, and filing treatment with IRD or a tax professional.
Treats basic salary plus EPF-eligible allowances as the contribution base, deducts employee EPF at 8% from gross pay, and adds employer EPF at 12% and ETF at 3% on top of gross to arrive at total cost to company.
Statutory minimums only. Which allowances are EPF-eligible is a question of fact about your pay structure, and many employers contribute above the minimum. Gratuity, APIT, insurance, and other benefits sit outside this calculation.
Converts billable hours per week into monthly hours at 4.33 weeks per month, adds business expenses to the target take-home to get the amount that must be earned, then divides by monthly hours. The optimal rate grosses that figure up by 30% to provide a 20% margin and a 10% tax provision.
Primary sources
The 20% margin and 10% tax provision are planning defaults chosen for this tool, not rates set by any authority. Your actual tax liability depends on your total income and the current personal income tax bands, and the exchange rate you receive depends on your bank and payment processor.
Adds cost of goods to shipping and packaging to get total unit cost, then solves for the selling price that leaves the target gross margin using price = cost divided by one minus the margin. Markup is reported as profit over cost, and the discount simulation recalculates margin at the reduced price.
Gross margin only. It excludes rent, salaries, marketing, payment fees, returns, and any tax on the sale, so a healthy gross margin here does not by itself mean the business is profitable.
Projects annual EPF and ETF balances from statutory minimum contribution rates and the salary-growth and annual-return assumptions entered by the user.
Primary sources
This is an illustrative projection, not an EPF, ETF, or IRD statement. It excludes withdrawals and tax and cannot predict future declared interest or dividends.
Applies the two Section 5 formulas - half a month's wage per completed year for monthly-rated employees, fourteen days' wage per completed year for daily and piece-rated employees - to the last drawn wage, gated by the five-year qualifying period and the fifteen-employee coverage threshold.
Primary sources
This is an estimate of the statutory minimum. A contract, collective agreement, or company policy can provide more, and the treatment of a final part-year varies between employers. Gratuity disputes are handled by the Commissioner of Labour.
Applies flat interest to the amount financed for the full term, divides the total by the number of instalments, then solves numerically for the reducing-balance rate that would produce the same instalment.
Primary sources
An estimate from the figures entered. Agreements vary in how they treat insurance, registration, and early settlement, and the settlement figure on a flat-rate agreement is set by the contract rather than by recalculating interest.
Divides fixed costs by contribution per unit, where contribution is price minus variable cost. Margin of safety compares expected volume against the break-even volume, and the target-profit figure treats the desired profit as an addition to fixed costs.
A gross-margin model for a single product at a single price. It excludes tax, and assumes every cost is cleanly either fixed or variable, which real cost structures rarely are.
Implements the published Sri Lanka Customs computation formulae exactly: duty and PAL on CIF, cess on CIF plus 10%, excise on CIF plus 15% with duty, cess, and PAL added, and VAT and SSCL on CIF plus 10% with every earlier levy added. Rates are entered by the user because they vary by HS code.
Primary sources
The cascade is applied exactly as published, but the rates for any given HS code change with each budget and by gazette during the year. Confirm current rates with Sri Lanka Customs or a clearing agent before relying on a figure.
Applies the PUCSL domestic tariff blocks and fixed charges for a standard 30-day billing cycle.
Primary sources
The estimate assumes a 30-day domestic billing cycle. PUCSL adjusts block limits for other billing periods, and an issued bill may also include prior balances or account adjustments.
Subtracts the two calendar dates the way a person would by hand, borrowing days from the preceding month and months from the year. Both dates are built from their parts in local time, so the result is the same calendar difference for a reader anywhere in the world.
Calendar arithmetic on the proleptic Gregorian calendar. Where a legal age threshold matters, confirm the rule that applies -- some jurisdictions count an age as attained on the day before the anniversary.
Divides trip distance by the vehicle's fuel efficiency to get litres consumed, multiplies by the price per litre, and divides the total between the number of people sharing. A round trip doubles the distance before anything else is calculated.
Primary sources
Fuel only. Tolls, parking, wear, and any difference between your real-world consumption and the efficiency figure entered are not included, so the true cost of a trip is higher than the number shown.
Handles the three distinct questions people mean by percentage: a share of a whole, one number expressed as a percentage of another, and the change between two numbers. Each uses its own formula, shown alongside the result.
Pure arithmetic with no rounding applied beyond display. Where a percentage carries legal or financial consequence, check the rounding convention the institution applies.
Applies the tip percentage to the bill amount entered, adds it to the total, and divides by the number of people. Rounding options adjust the per-person figure to a convenient note value.
Primary sources
Whether you tip on the pre-tax or post-tax amount is a personal choice, not a rule. Check whether a service charge has already been added before deciding what to leave.
Converts through a single base unit per category -- metres for length, kilograms for weight -- using exact SI-defined factors. Temperature is converted through Celsius, since its scales differ by offset as well as by ratio.
Primary sources
Conversion factors are exact by definition, so results are limited only by display rounding. Where a tolerance matters, carry the full precision rather than the rounded figure shown.
Splits the number into its year, day-of-year, and serial fields, removes the 500 offset that marks a female holder, and resolves the day-of-year against the fixed 366-day calendar the Department of Registration of Persons encodes against.
Primary sources
This tool reads what a number encodes. It cannot confirm that a number was issued, that it is still current, or that it belongs to a particular person - no published check-digit algorithm exists for the Sri Lankan NIC.
Dates are taken from the Holidays in Sri Lanka calendar Google publishes as a public ICS feed, transcribed by script rather than by hand. Moon-sighting dependent dates are carried through with the source's own tentative flag, and long weekends are computed by scanning the year for runs of consecutive days off.
Primary sources
The definitive list for any year is the gazette published by the Ministry of Public Administration. Islamic holidays depend on a moon sighting and can move by a day. Ad-hoc holidays declared during the year - for elections or other reasons - cannot appear on a page prepared in advance.
Every document any tool on this site is built from, and the tools that depend on it. 50 primary sources in total.
Used by Ovulation Calculator.
Used by Unit Converter.
Used by IGCSE Grade Converter.
Used by Loan Eligibility (DBR).
Used by Loan / EMI Calculator.
Used by Loan / EMI Calculator, Loan Eligibility (DBR).
Used by Vehicle Lease EMI Calculator.
Used by Vehicle Lease EMI Calculator.
Used by EPF & ETF Calculator.
Used by Hire Purchase Calculator.
Used by Housing Loan Calculator.
Used by FD & T-Bill Calculator.
Used by Fuel Cost & Road Trip Split.
Used by A/L Z-Score, O/L Results Checker.
Used by Holidays & Poya Days.
Used by Cost to Company (CTC).
Used by Gratuity Calculator.
Used by Gratuity Calculator.
Used by Government Pension.
Used by NIC Decoder.
Used by Cost to Company (CTC).
Used by EPF & ETF Calculator.
Used by Pregnancy Due Date.
Used by Holidays & Poya Days.
Used by Income Tax (APIT) Calculator, VAT & SSCL Invoice, EPF & ETF Calculator.
Used by Income Tax (APIT) Calculator.
Used by Freelancer Hourly Rate.
Used by Tip & Bill Split.
Used by FD & T-Bill Calculator.
Used by BMR & Calorie Needs.
Used by O/L Results Checker.
Used by Asian BMI & Ideal Weight.
Used by Blood Donation Date.
Used by Ovulation Calculator.
Used by Pregnancy Due Date.
Used by IGCSE Grade Converter.
Used by Electricity Bill (PUCSL).
Used by Electricity Bill (PUCSL).
Used by NIC Decoder.
Used by Import Cost Calculator.
Used by Import Cost Calculator.
Used by Housing Loan Calculator.
Used by University Cut-offs.
Used by A/L Z-Score.
Used by Attendance Tracker, University Cut-offs.
Used by Target GPA Estimator, GPA Calculator.
Used by Target GPA Estimator, GPA Calculator.
Used by GPA Calculator.
Used by BMR & Calorie Needs.
Used by Asian BMI & Ideal Weight.
